Intravascular Optical Coherence Tomography
Number: 0829
Table Of Contents
PolicyApplicable CPT / HCPCS / ICD-10 Codes
Background
References
Policy
Scope of Policy
This Clinical Policy Bulletin addresses intravascular optical coherence tomography.
-
Medical Necessity
Aetna considers intravascular optical coherence tomography (OCT) medically necessary for procedural guidance to reduce ischemic events in members with acute coronary syndrome (ACS) undergoing coronary stent implantation in the left main artery or in complex lesions.
-
Experimental, Investigational, or Unproven
Aetna considers intravascular optical coherence tomography (OCT) experimental, investigational, or unproven for all other indications, including the following because of insufficient evidence of its effectiveness.
- Assessment of carotid artery stenosis/stroke risk
- Assessment of pulmonary arterial wall fibrosis (as a prognostic marker of pulmonary arterial hypertension)
- Detection of cardiac allograft vasculopathy following heart transplantation
- Diagnosis and rupture assessment of intracranial aneurysm
- Diagnosis of pulmonary artery thrombus
- Evaluation of arterial bifurcations covered by flow diverting stents
- Evaluation of coronary stenosis in individuals with antiphospholipid syndrome
- Evaluation of pulmonary arterial vasculopathy in systemic sclerosis
- Evaluation of pulmonary vascular structures in individuals with congenital heart diseases
- Follow-up evaluation of post-stent placement
- Guidance of percutaneous treatment of coronary bifurcation disease
- Follow-up evaluation of renal arteries after radiofrequency catheter-based renal denervation
- Imaging of cerebral vessels
- Prediction of periprocedural myocardial injury in persons with stable angina pectoris
- Treatment (as an adjunct to percutaneous coronary interventions).
-
Related Policies
- CPB 0228 - Cardiac Computed Tomography (CT), Coronary CT Angiography, Calcium Scoring and CT Fractional Flow Reserve
- CPB 0381 - Cardiovascular Disease Risk Tests
- CPB 0382 - Intravascular Ultrasound
- CPB 0491 - Coronary Artery Brachytherapy and Other Adjuncts to Coronary Interventions
- CPB 0520 - Magnetic Resonance Imaging of the Cardiovascular System - Cardiac MRI
- CPB 0579 - T-Wave Alternans
- CPB 0789 - Acute Ischemic Stroke Treatments
Background
Intravascular optical coherence tomography (OCT) is a catheter‑based imaging modality that uses near‑infrared light to generate high‑resolution, cross‑sectional images of coronary arteries from within the vessel lumen. By measuring the echo time delay of backscattered light, it produces micrometer‑scale detail allowing clinicians to assess plaque morphology, stent expansion and apposition, and vessel wall microstructures. OCT is may be used during percutaneous coronary interventions (PCI) to optimize stent deployment and to identify features such as thin‑cap fibroatheromas, thrombus, or dissections, supporting more precise, evidence‑guided decision‑making during complex coronary procedures.
Disruption of a vulnerable coronary plaque with subsequent thrombosis is currently recognized as the primary mechanism for acute myocardial infarction. Although such plaques are considered to have a thin (less than 65 microns) fibrous cap overlying a lipid pool, imaging modalities in current clinical practice do not have sufficient resolution to identify thin fibrous caps. Optical coherence tomography (OCT) is a new imaging technology capable of obtaining cross-sectional images of coronary vessels. As an optical analog of ultrasound, OCT uses a high-bandwidth infra-red light source instead of an ultrasound-emitting crystal to create high-resolution cross-sectional images of coronary vessels. The resolution of the current OCT system is 10 to 20 microns, which is approximately 10-fold higher than that of intra-vascular ultrasound (IVUS). Furthermore, OCT can visualize stent mal-apposition and tissue protrusion after stenting and neointimal hyperplasia at follow-up.
Stamper et al. (2006) stated that the identification of unstable plaque is central to risk-stratifying patients for acute coronary events, and OCT is a modality that has shown considerable promise for the identification of high-risk plaques. The authors summarized the current state of intravascular OCT imaging, focusing on potential markers of instability and current limitations. They concluded that OCT is a promising technology for the assessment of vulnerable and unstable plaque. The advantages of OCT include its high resolution, fast data acquisition rate, small, inexpensive designs, as well as its ability to be combined with adjuvant techniques. They stated that future work will focus on improving plaque risk stratification, especially the identification of reliable markers within the images. Manfrini et al. (2007) stated that intravascular OCT's high resolution (10 to 20 microns) makes it a very interesting method for assessing atherosclerotic plaque microstructure in patients suffering from coronary artery disease (CAD). However, significant limitations still exist, including poor penetration in non-transparent tissue. Moreover, Kubo and Akasaka (2008) noted that OCT is a specialized research tool that might provide new insights into the diagnosis and treatment of CAD.
Jang et al. (2005) investigated the application of intravascular optical coherence tomography (OCT) for assessing vulnerable plaques in patients undergoing cardiac catheterization due to acute and stable coronary syndromes. The study enrolled patients and categorized them based on their clinical presentations, which included recent acute myocardial infarction (AMI), acute coronary syndromes (ACS) such as non-ST-segment elevation AMI and unstable angina pectoris (UAP), or stable angina pectoris (SAP). Two observers independently analyzed the images using validated criteria for plaque characterization. Out of 69 enrolled patients, 57 had analyzable images, comprising 20 with AMI, 20 with ACS, and 17 with SAP. The results showed that lipid-rich plaques, defined as those with lipid occupying at least two quadrants of the cross-sectional area, were present in 90% of the AMI group, 75% of the ACS group, and 59% of the SAP group, with a p-value of 0.09. The median minimum thickness of the fibrous cap was 47.0 microns for AMI, 53.8 microns for ACS, and 102.6 microns for SAP, with a p-value of 0.034. The frequency of thin-cap fibro-atheroma (TCFA), characterized by lipid-rich plaques with a cap thickness of 65 microns or less, was found to be 72% in the AMI group, 50% in the ACS group, and 20% in the SAP group, with a p-value of 0.012. No complications related to the procedure were reported. The authors concluded that OCT is a safe and effective method for in vivo characterization of coronary atherosclerotic plaques, noting that TCFA was more frequently observed in patients with AMI or ACS compared to those with SAP. This study was the first to compare detailed in vivo plaque morphology across different clinical presentations, although it faced limitations such as interference from blood, poor tissue penetration, and a relatively small sample size.
Raffel et al. (2008) investigated the in vivo relationship between coronary artery remodeling and the underlying plaque characteristics identified by optical coherence tomography (OCT). In this study, OCT and intravascular ultrasound (IVUS) imaging were performed at corresponding sites in patients undergoing catheterization, with OCT plaque characteristics such as lipid content, fibrous cap thickness, and macrophage density assessed using previously validated criteria. Thin-cap fibro-atheroma (TCFA) was defined as lipid-rich plaque occupying two or more quadrants with a fibrous cap thickness of less than 65 microns. The remodeling index (RI) was calculated as the ratio of the lesion area to the reference external elastic membrane area. A total of 54 lesions from 48 patients were imaged, revealing that positive remodeling was more frequently associated with lipid-rich plaques (100% compared to 60% and 47.4%, p = 0.01), thinner fibrous caps (median thickness of 40.2 microns versus 51.6 microns and 87 microns, p = 0.003), and the presence of TCFA (80% versus 38.5% and 5.6%, p < 0.001). Additionally, fibrous cap macrophage density was higher in plaques with positive remodeling, showing a positive linear correlation with the RI (r = 0.60, p < 0.001). The authors concluded that coronary plaques exhibiting positive remodeling display characteristics typical of vulnerable plaques, which may help explain the association between positive remodeling and unstable clinical presentations. They emphasized the need for prospective, longitudinal studies with larger cohorts to confirm these findings and explore their clinical significance. However, the study faced limitations, including potential selection bias, blood interference, limited penetration depth (2 to 3 mm), and a small cohort size.
Yamaguchi et al. (2008) assessed the safety and feasibility of intracoronary imaging using optical coherence tomography (OCT) in a clinical setting, enrolling 76 patients with coronary artery disease (CAD) from eight centers. The OCT imaging system utilized (ImageWire, Light Imaging Inc., Westford, MA) features a 0.006-inch fiberoptic core that rotates within a 0.016-inch transparent sheath. OCT imaging was conducted during artery occlusion with a compliant balloon and continuous flushing, while intravascular ultrasound (IVUS) imaging was performed in the same segments. The average vessel occlusion time was 48.3 ± 13.5 seconds, with an occlusion-balloon pressure of 0.4 ± 0.1 atmospheres and flushing with lactated Ringer's solution at a rate of 0.6 ± 0.4 ml/s. No significant adverse events, such as vessel dissection or fatal arrhythmia, were reported. The procedural success rates were 97.3% for OCT and 94.5% for IVUS. Notably, the OCT image wire successfully crossed five out of six tight lesions that the IVUS catheter could not navigate. Among the 98 lesions where both OCT and IVUS were performed, OCT demonstrated superior visualization of the lumen border. Additionally, minimum lumen diameter and area measurements showed strong correlations between OCT and IVUS imaging (r = 0.91, p < 0.0001 and r = 0.95, p < 0.0001, respectively). The authors concluded that their study confirmed the safety and feasibility of OCT imaging in clinical practice, emphasizing the need for further analysis with larger populations to establish and refine the clinical applications and safety of the intravascular OCT imaging system. However, the study had limitations, including a small sample size and the fact that it was not designed to evaluate the potential advantages of intravascular OCT over IVUS in terms of increased resolution.
Kawamori et al. (2010) investigated the utility of optical coherence tomography (OCT) for evaluating vessel response after stent implantation, comparing its effectiveness with that of intravascular ultrasound (IVUS). The study enrolled 18 patients undergoing percutaneous coronary intervention (PCI) who consented to the use of both IVUS and OCT before and after the procedure. The results indicated that the lumen area at the distal site of the culprit lesion was smaller on OCT images than on IVUS images due to proximal vessel occlusion, while the lumen area at the proximal site showed no significant difference between the two imaging modalities (distal site: 4.6 ± 2.0 mm² versus 5.0 ± 1.8 mm²; p = 0.0004; proximal site: 5.5 ± 2.3 mm² versus 5.6 ± 2.3 mm²; p = 0.8160). Stent malapposition was observed more frequently with OCT (30%) compared to IVUS (5%, p = 0.0381). Additionally, stent edge dissection was detected in 10% of cases by OCT, while IVUS did not identify any instances. Tissue prolapse was found in all stents using OCT, but only in 5% of cases with IVUS. Thrombus formation was noted in 15% of cases by OCT and in 5% by IVUS. The authors concluded that proximal coronary occlusion during OCT imaging may have contributed to the underestimation of vessel sizing at the distal reference. These findings suggest that OCT may provide more detailed information regarding tissue prolapse, thrombus formation, and edge dissection compared to IVUS. They emphasized the need for further studies to assess the clinical utility of OCT. However, the study had several limitations, including its non-randomized, retrospective design based on a small sample size, which raises the possibility of selection bias. Additionally, OCT has limited capability to visualize certain lesions, such as ostial lesions, due to the challenges of creating a blood-free environment with an occlusion balloon. While a non-occlusion flushing technique may help visualize proximal lesions, it has limitations regarding scanning length. Severely calcified and tortuous vessels also posed challenges for OCT imaging due to difficulties in passing the occlusion balloon through the lesions. Furthermore, the current OCT system has a limited penetration depth, which can hinder the visualization of the entire vessel structure. The authors suggested that a new imaging device capable of achieving greater penetration depth without sacrificing resolution, such as a combined IVUS and OCT system, could provide more comprehensive information and potentially enhance outcomes during PCI.
Kubo et al. (2011) highlighted that recent intravascular ultrasound (IVUS) studies have shown that hypo-echoic plaques exhibiting deep ultrasound attenuation, despite the absence of bright calcium, are common in acute coronary syndromes (ACS). This "attenuated plaque" may serve as an IVUS indicator of unstable lesions. In their study, the researchers utilized optical coherence tomography (OCT) to analyze lesion characteristics in 104 patients with unstable angina pectoris (UAP), comparing IVUS-detected attenuated plaques with non-attenuated plaques. They found that IVUS-detected attenuated plaques were present in 41 patients (39%), and OCT revealed that lipidic plaques (88% versus 49%, p < 0.001), thin-cap fibro-atheromas (TCFA) (48% versus 16%, p < 0.001), plaque ruptures (44% versus 11%, p < 0.001), and intra-coronary thrombus (54% versus 17%, p < 0.001) were significantly more prevalent in the attenuated plaques compared to the non-attenuated ones. The authors concluded that IVUS-detected attenuated plaques exhibit many characteristics associated with unstable coronary lesions, suggesting that the presence of such plaques may be an important marker of lesion instability. They called for well-designed studies to determine the prognostic value of OCT in the context of ACS. However, the study had several limitations, including its retrospective design involving non-consecutive UAP patients, which necessitates further examination of the prevalence, clinical features, and prognostic implications of IVUS-detected attenuated plaques in larger population studies. Additionally, the lack of a comparison group with stable presentations, potential interference from acoustic shadowing in the IVUS analysis affecting calculations of remodeling and plaque burden, and the limitations of OCT in visualizing and measuring the entire atherosclerotic plaque due to signal attenuation of lipidic tissue or thrombus were noted. Furthermore, the use of 40-MHz IVUS transducers, as employed in previous studies of attenuated plaques, may limit the applicability of these findings to IVUS images obtained with other frequency transducers, since the frequency can influence signal penetration, with 20-MHz transducers used in virtual histology IVUS providing greater penetration than 40-MHz transducers.
Miyamoto et al. (2011) investigated the plaque characteristics of thin-cap fibro-atheromas (TCFA) identified by optical coherence tomography (OCT) using integrated backscatter intravascular ultrasound (IB-IVUS). The study analyzed 81 coronary lesions with a plaque burden greater than 40%, employing both IB-IVUS and OCT for assessment. TCFA was defined by OCT as the presence of a thin fibrous cap (less than 65 microns) over a signal-poor lesion with a diffuse border indicative of a lipid-rich plaque. Using conventional gray-scale IVUS, the researchers measured the external elastic membrane (EEM) cross-sectional area (CSA), lumen CSA, plaque plus media (P+M) CSA, plaque burden, and remodeling index (RI). IB-IVUS further classified plaque characteristics into fibrosis, dense fibrosis, calcification, or lipid pool. The study identified 40 TCFAs (49%) and 41 non-TCFAs. The results showed that EEM CSA, P+M CSA, plaque burden, and RI were significantly larger in OCT-derived TCFAs compared to non-TCFAs. Additionally, the percentage of lipid pool area (calculated as lipid pool area/P+M CSA × 100) was significantly higher in OCT-derived TCFAs (62.4 ± 12.8%) than in non-TCFAs (38.4 ± 13.1%, p < 0.0001), while the percentage of fibrosis area (fibrosis area/P+M CSA × 100) was significantly lower in TCFAs (34.6 ± 11.4%) compared to non-TCFAs (50.5 ± 8.7%, p < 0.0001). Receiver-operator characteristic curve analysis indicated that a percentage lipid pool area greater than or equal to 55%, a percentage fibrosis area less than or equal to 41%, and an RI greater than or equal to 1.0 were predictive of OCT-derived TCFAs. The authors concluded that OCT-derived TCFAs exhibited larger plaque burdens and positive remodeling, characterized by a predominant lipid component and less fibrous plaque as assessed by IB-IVUS. However, the study had several limitations, including a relatively small patient sample, the potential for OCT image artifacts leading to misinterpretations, and the observation of only limited vessel areas due to system constraints in imaging certain complex lesions.
Uemura et al. (2012) investigated the morphological characteristics of non-significant coronary plaques (NSCPs) in patients with coronary artery disease (CAD) using intravascular optical coherence tomography (OCT). The study enrolled 53 consecutive CAD patients undergoing percutaneous coronary intervention (PCI) and identified 69 NSCPs (defined as having less than 50% diameter stenosis) based on baseline angiograms. The baseline characteristics of these NSCPs were evaluated using OCT, and patients were followed up prospectively. At the time of the second coronary angiography, the researchers correlated the baseline OCT characteristics with plaque progression. Over a 7-month follow-up period, 13 NSCPs exhibited angiographic progression, while 56 did not. The baseline minimum lumen diameter and diametric stenosis were similar between NSCPs that progressed and those that did not. However, NSCPs that showed progression had a significantly higher incidence of intimal laceration (61.5% versus 8.9%, p < 0.01), micro-channels (76.9% versus 14.3%, p < 0.01), lipid pools (100% versus 60.7%, p = 0.02), thin-cap fibro-atheromas (TCFA) (76.9% versus 14.3%, p < 0.01), macrophage images (61.5% versus 14.3%, p < 0.01), and intra-luminal thrombi (30.8% versus 1.8%, p < 0.01). Univariate regression analysis indicated that the presence of TCFA and micro-channel images were strongly correlated with subsequent luminal progression, with odds ratios (OR) of 20.0 (p < 0.01) for both. The authors concluded that the complex characteristics of TCFA and micro-channels identified by OCT could serve as potential predictors of subsequent progression of NSCPs in patients with CAD. However, the study had several limitations, including a small sample size, the limited penetration depth of intravascular OCT, which made it challenging to assess plaque features deep within the coronary artery walls, and the technical complexity of the procedures required to obtain high-quality OCT images. Additionally, it could not be entirely ruled out that the image wire and occlusion balloon used during the procedure may have caused vessel injury, contributing to subsequent plaque progression.
Gonzalo et al. (2012) stated that the value of OCT to determine stenosis severity remains unsettled. These researchers evaluated the diagnostic efficiency of OCT in identifying hemodynamically severe coronary stenoses as determined by fractional flow reserve (FFR). Concomitant OCT and IVUS area measurements were performed in a subgroup of patients to compare the diagnostic efficiency of both techniques. A total of 61 stenoses with intermediate angiographic severity were studied in 56 patients. Stenoses were labeled as severe if FFR was less than or equal to 0.80. Optical coherence tomography interrogation was performed in all cases, with concomitant IVUS imaging in 47 cases. Angiographic stenosis severity was 50.9 ± 8% diameter stenosis with a 1.28 ± 0.3 mm minimal lumen diameter. Fractional flow reserve was less than or equal to 0.80 in 28 (45.9%) stenoses. An overall moderate diagnostic efficiency of OCT was found (area under the curve [AUC]: 0.74; 95% confidence interval [CI]: 0.61 to 0.84), with sensitivity/specificity of 82%/63% associated with an optimal cutoff value of 1.95 mm². Comparison of the results in patients with simultaneous IVUS and OCT imaging revealed no significant differences in the diagnostic efficiency of OCT (AUC: 0.70; 95% CI: 0.55 to 0.83) and IVUS (AUC: 0.63; 95% CI: 0.47 to 0.77; p = 0.19). Sensitivity/specificity for IVUS was 67%/65% for an optimal cutoff value of 2.36 mm². In the subgroup of small vessels (reference diameter less than 3 mm), OCT showed a significantly better diagnostic efficiency (AUC: 0.77; 95% CI: 0.60 to 0.89) than IVUS (AUC: 0.63; 95% CI: 0.46 to 0.78) in identifying functionally significant stenoses (p = 0.04). The authors concluded that OCT has a moderate diagnostic efficiency in identifying hemodynamically severe coronary stenoses. Although OCT seems slightly superior to IVUS for this purpose (particularly in vessels less than 3 mm), its low specificity precludes its use as a substitute for FFR in functional stenosis assessment.
In an assessment of clinical applications of OCT, Prati et al. (2010) stated that OCT is a novel intravascular imaging modality that enables high-resolution arterial wall imaging, in the range of 10 to 20 microns. These investigators noted that OCT has the potential to become the most accurate imaging modality to assess lumen dimensions and facilitate the application of automatic algorithms for measurements. However, further studies are needed to address both this point and the identification of lumen area values that discriminate lesions capable of inducing effort ischemia. They also emphasized that the identification of atherosclerotic plaque components by OCT depends on the penetration depth of the incident light beam into the vessel wall. The depth of penetration is greatest for fibrous tissue and least for thrombi, with calcium and lipid tissue having intermediate values. They stated that additional clinical–pathological correlation studies, particularly with the new upcoming technologies, are important to further define tissue characteristics by OCT. The main limitation of OCT centers on its inability to measure plaque burden whose thickness exceeds 1.3 to 1.5 mm. This drawback may affect the role of OCT in the guidance of interventional procedures, as well as overall disease severity. Furthermore, these researchers noted that while OCT may prove to be an important addition to IVUS because it can discriminate among the different plaque components whose changes may be important in serial studies, robust validation studies are needed to verify whether OCT is capable of measuring serial changes in plaque components indicative of vulnerability, such as fibrous cap thickness or lipid pool extension. Additionally, due to its ability to address plaque components related to vulnerability, OCT may have a role in assessing the risk of myocardial infarction. This clinical application, however, needs to be proven in the future.
Elmariah and Jang (2011) stated that, "[a]lthough the ability to identify and characterize thrombus using OCT is an advance over other imaging modalities, the clinical implications of this information remain unclear. In the setting of PCI, angiographically obvious intra-coronary thrombus is a known risk factor for adverse cardiovascular events; however, at high resolution, thrombus is a very common finding on OCT after PCI. Further quantification and characterization of intra-coronary thrombus using OCT may effectively risk-stratify patients undergoing PCI and may guide anti-thrombotic therapy. The ongoing Massachusetts General Hospital OCT Registry, an international collaborative effort that will include 3,000 patients, may ultimately answer questions regarding the impact of thrombus burden and characteristics on patient outcomes."
Cambon et al. (2011) stated that OCT is a new imaging technique recently applied to coronary arteries. With a resolution 10 times higher than that of IVUS, it allows for an analysis of the atherosclerotic plaque and its components, indicating its possible vulnerable character, and can identify the culprit lesion and the presence of thrombus in the course of acute events. It allows for quality control of good apposition of stents to the wall and essentially tracks downstream dissection. In the longer term, it evaluates endothelization and in-stent re-stenosis. Its scope thus extends to basic research and the pharmaceutical industry, where it plays a new reference tool in the monitoring of atherosclerotic plaques and stents with drug treatment. This invasive imaging technique is limited by its cost and artifacts, but new generation OCT can better overcome these limitations. The authors concluded that OCT appears to be a promising intravascular imaging technique whose feasibility and clinical applications, however, require confirmation by randomized clinical trials to better define its place in the cardiac catheterization laboratory.
Gutierrez-Chico et al. (2012) stated that in cardiology, OCT has remained hitherto a research tool for the characterization of vulnerable plaques and evaluation of neointimal healing after stenting. However, OCT is now successfully applied in different clinical scenarios, and the introduction of frequency domain analysis has simplified its application to the point that it can be considered a potential alternative to IVUS for clinical decision-making in some cases. These investigators reviewed the use of OCT for the assessment of lesion severity, characterization of acute coronary syndromes (ACS), guidance of intra-coronary stenting, and evaluation of long-term results.
Tsimikas and DeMaria (2012) stated that OCT is an emerging technology. They noted that "due to its limited penetration and high attenuation by some plaque components, it remains to be seen whether it will ultimately discriminate lipid versus nonlipid components such as the necrotic cores that are associated with high potential for plaque rupture. It also cannot fully measure plaque burden, particularly in large arteries, or adequately assess remodeling due to depth of penetration issues, and may not be amenable to testing pharmacological therapeutic interventions as IVUS." Several gaps in knowledge remain: most of the data come from small studies and largely descriptive datasets; limitations in imaging the vessel wall related to the procedure and generation of imaging artifacts will likely become more apparent as more experience is obtained; the OCT evidence based on plaque composition will need to be supported by future studies. To define the ultimate clinical utility of OCT, standards will need to be defined prospectively and linked to outcomes with appropriate studies.
In a guideline for percutaneous coronary intervention, the American College of Cardiology (Levine et al., 2011) stated that "[t]he appropriate role of optical coherence tomography in routine clinical decision making has not been established." Furthermore, an UpToDate review on "Intravascular ultrasound, optical coherence tomography, and angioscopy of coronary circulation" (Regar et al., 2012) states that "[t]oday, no clinical indications for OCT imaging are established. There are no randomized data supporting a prognostic role for OCT in catheter-based intervention. Preliminary data on OCT indicate that it can change the operator’s intention-to-treat and modify the overall revascularization strategy, potentially avoiding unnecessary interventional procedures. OCT might be efficient in complex interventions, including treatment of the left main stem, bifurcations, as well as in all cases of angiographically ambiguous lesions and in-stent failures. Two other potential uses of OCT are identification of an angiographically unclear lesion and assessment of stent failure."
Yonetsu et al. (2013) stated that since its invention in the late 1990s, intravascular OCT has been rapidly adopted in clinical research and, more recently, in clinical practice. Given its unprecedented resolution and high image contrast, OCT has been used to visualize plaque characteristics and to evaluate the vascular response to PCI. In particular, OCT is becoming the standard modality to evaluate in vivo plaque vulnerability, including the presence of lipid content, thin fibrous cap, or macrophage accumulation. Furthermore, OCT findings after stent implantation, such as strut apposition, neointimal hyperplasia, strut coverage, and neo-atherosclerosis, are used as surrogate markers of the vascular response. New applications for OCT are being explored, such as transplant vasculopathy or non-coronary vascular imaging. The authors concluded that although OCT has contributed to cardiovascular research by providing a better understanding of the pathophysiology of CAD, data linking the images and clinical outcomes are lacking. Moreover, they stated that prospective data are needed to prove that the use of OCT improves patient outcomes, which is the ultimate goal of any clinical diagnostic tool.
Jia and colleagues (2013) characterized the morphological features of plaque erosion and calcified nodule in patients with acute coronary syndrome (ACS) by OCT. A total of 126 patients with ACS who had undergone pre-intervention OCT imaging were included. The culprit lesions were classified as plaque rupture (PR), erosion (OCT-erosion), calcified nodule (OCT-CN), or others using a new set of diagnostic criteria for OCT. The incidences of PR, OCT-erosion, and OCT-CN were 43.7%, 31.0%, and 7.9%, respectively. Patients with OCT-erosion were the youngest compared with those with PR and OCT-CN (53.8 ± 13.1 years versus 60.6 ± 11.5 years, 65.1 ± 5.0 years, p = 0.005). Compared with patients with PR, presentation with non-ST-segment elevation ACS (NSTE-ACS) was more common in patients with OCT-erosion (61.5% versus 29.1%, p = 0.008) and OCT-CN (100% versus 29.1%, p < 0.001). Optical coherence tomography-erosion had a lower frequency of lipid plaque (43.6% versus 100%, p < 0.001), thicker fibrous cap (169.3 ± 99.1 μm versus 60.4 ± 16.6 μm, p < 0.001), and smaller lipid arc (202.8 ± 73.6° versus 275.8 ± 60.4°, p < 0.001) than PR. The diameter stenosis was least severe in OCT-erosion, followed by OCT-CN and PR (55.4 ± 14.7% versus 66.1 ± 13.5% versus 68.8 ± 12.9%, p < 0.001). The authors concluded that OCT is a promising modality for identifying OCT-erosion and OCT-CN in vivo. Optical coherence tomography-erosion is a frequent finding in patients with ACS, especially in those with NSTE-ACS and younger patients, whereas OCT-CN is the least common etiology for ACS and is more common in older patients.
Domingo et al. (2013) correlated pulmonary arterial (PA) remodeling estimated by PA fibrosis in pulmonary arterial hypertension (PAH) with clinical follow-up. Histology of PA specimens was also performed. A total of 19 patients, aged 54 ± 16 (4 men), functional class II to III, were studied with right heart catheterization, PA-IVUS, and OCT in the inferior lobe segment. Pulmonary arterial wall fibrosis was obtained by OCT (area of fibrosis/PA cross-sectional area × 100). Patients’ follow-up was blind to OCT. Events were defined as mortality, lung transplantation, need for intravenous prostaglandins, or onset of right ventricular failure. Optical coherence tomography measurements showed high intra- and inter-observer agreement. There was a good correlation between OCT and histology in PA fibrosis from explanted lungs. The area of fibrosis was 1.4 ± 0.8 mm², and % fibrosis was 22.3 ± 8. Follow-up was 3.5 years (2.5 to 4.5). Optical coherence tomography % Fib was significantly correlated with PA capacitance (r = -0.536) and with pulmonary vascular resistance (r = 0.55). Patients were divided according to the median value of PA fibrosis. There were 10 patients with high fibrosis (greater than or equal to 22%) and 9 with low fibrosis (less than 22%). Events occurred in 6 (1 death, 1 lung transplantation, 2 intravenous prostaglandins, and 2 right heart failures) out of 10 patients with high fibrosis and in 0 out of 9 patients with low fibrosis (p < 0.01). The authors concluded that in PAH, the severity of PA remodeling assessed by OCT wall fibrosis was significantly predictive of severely unfavorable clinical outcomes. Moreover, they stated that in vivo assessment of pulmonary arterial wall fibrosis by intravascular OCT in PAH is a promising new prognostic marker of adverse clinical outcomes.
Jones and colleagues (2014) examined carotid plaque characteristics in symptomatic versus asymptomatic patients with the use of non-occlusive OCT. These researchers hypothesized that OCT might be useful for the identification of low-risk versus high-risk carotid plaque features and help to understand the relationship between carotid diameter stenosis and plaque morphology to ischemic stroke. A total of 53 patients undergoing diagnostic carotid angiography were studied with OCT. Data analysis was carried out by imaging experts who were unaware of the clinical characteristics of the study population. Plaque with American Heart Association (AHA) type VI complicated features was more common in symptomatic than asymptomatic patients (74.1% versus 36.4%, p = 0.02). This was largely driven by differences in the incidence of thin-cap fibro-atheroma with rupture (40.7% versus 13.6%, p = 0.056) and thrombus (67.7% versus 36.4%, p = 0.034). Conversely, non-type VI plaques were more common in asymptomatic than symptomatic patients (63.6% versus 25.9%, p = 0.02). No association between the degree of stenosis and plaque morphology was identified. The authors concluded that this retrospective analysis of carotid OCT data supported the hypothesis that the evaluation of carotid plaque characteristics with this high-resolution imaging technique has the potential to alter the understanding and treatment of carotid artery disease.
Zafar et al. (2014) noted that frequency domain OCT (FD-OCT) provides cross-sectional images of coronary arteries and deployed stents with micron resolution and measures lumen dimensions with excellent reproducibility. Frequency domain OCT combined with a blood flow resistance model can overcome many limitations of conventional measures of stenosis severity based on quantitative coronary angiography (QCA) and IVUS. These researchers investigated the relationship between pressure-derived FFR and FD-OCT-derived FFR, a new method for quantitative measurement of stenosis severity that estimates the blood flow resistance and microvascular resistance of the vessel segments imaged by FD-OCT. A total of 26 coronary stenoses in 20 patients were studied consecutively with QCA, pressure-derived FFR, and FD-OCT. There was a moderate but significant correlation between pressure-derived FFR and FD-OCT-derived FFR (r = 0.69, p < 0.001). Bland-Altman analysis showed that the mean differences between pressure-derived FFR and FD-OCT-derived FFR were 0.05 ± 0.14 (limits of agreement: -0.09 to 0.19). The root mean square error (RMSE) between FD-OCT-derived FFR and pressure-derived FFR was found to be ± 0.087 FFR units. The authors concluded that FD-OCT-derived FFR has the potential to become a valuable tool for the assessment of coronary artery stenosis.
Xie and colleagues (2015) stated that compared with IVUS, OCT has relative merits and demerits for detecting plaque characteristics. It remains unknown whether the IVUS and OCT evaluations of plaque progression/regression are consistent. These researchers analyzed the correlations between IVUS and OCT evaluations of plaques at single time points and compared temporal changes in the IVUS and OCT data. A total of 88 lipid-rich plaques from 65 patients with CAD were analyzed with IVUS and OCT at baseline and 12-month follow-up. Fibrous cap thickness on OCT was negatively correlated with total atheroma volume on IVUS (r = -0.28, p = 0.009), but not with percent atheroma volume (p = 0.84). Changes on OCT were not significantly correlated with changes on IVUS. Plaques that showed progression, regression, or no change on IVUS showed no differences in terms of changes in the OCT parameters fibrous cap thickness (p = 0.199), maximum lipid core arc (p = 0.755), mean lipid core arc (p = 0.936), and lipid index (p = 0.91). The incidence of TCFA was similar among the above three plaque groups at baseline (p = 0.79) and follow-up (p = 0.609). The authors concluded that although fibrous cap thickness on OCT was negatively correlated with plaque size on IVUS at single time points, changes in OCT parameters were not correlated with changes in IVUS measures over time. They stated that lesion progression/regression on IVUS was not associated with changes in OCT parameters (fibrous cap thickness, lipid core arc, lipid index, and TCFA).
Karimi Galougahi et al. (2023) highlight that optical coherence tomography (OCT) is the preferred imaging modality for acute coronary syndrome (ACS) due to its high axial resolution. During OCT imaging, near-infrared light is directed at the vessel wall while flushing blood from the lumen, resulting in high-resolution, cross-sectional, and three-dimensional images of the vessel. This technique allows for detailed visualization of the innermost tunica intima as a signal-rich layer, the tunica media as signal-poor, and the outermost adventitia as another signal-rich area, providing near-histological detail of plaque morphology and real-time insights into plaque disruption mechanisms. Studies employing intravascular OCT have enhanced the understanding of the key triggers and substrates for atherothrombotic events leading to ACS, with imaging findings reflecting characteristics of coronary atherosclerosis seen in post-mortem histopathological studies. OCT demonstrates good inter- and intra-observer reliability (κ = 0.83–0.84) and acceptable sensitivity and specificity across various plaque morphologies, outperforming intravascular ultrasound (IVUS) regardless of observer experience. However, the need for pre-dilatation and/or thrombectomy to restore antegrade flow during OCT imaging of thrombotic culprit lesions can distort the underlying plaque morphology. While more than half of ACS cases involve plaques with ruptured caps, one-third are attributed to plaque erosions, which may benefit from a conservative no-stenting approach supported by small, non-randomized studies, warranting further investigation in larger randomized trials. Additionally, intracoronary OCT serves as a valuable tool in diagnosing and managing rare ACS causes, such as eruptive calcified nodules, spontaneous coronary artery dissection (SCAD), and coronary spasm or embolism. Insights from mechanistic studies using OCT-defined intraplaque features (IFC), particularly regarding the roles of innate and adaptive immunity, may open avenues for treatments beyond traditional coronary interventions and antithrombotic therapies, including immune system modulation. The current evidence supporting the use of intravascular OCT to optimize primary PCI in ACS calls for validation through randomized controlled trials with long-term follow-up.
In a scientific statement from the American Heart Association regarding acute coronary syndromes (ACS) in premenopausal women, Kovacic et al. (2026) noted that intravascular imaging using optical coherence tomography (OCT) or intravascular ultrasound (IVUS) offers enhanced identification of the culprit vessel and evaluation of plaque morphology in ACS caused by atherosclerotic coronary artery disease (CAD) compared to angiography alone. Current guidelines advocate for the use of intracoronary imaging to guide percutaneous coronary intervention (PCI) in patients with ACS or complex CAD; however, there are no specific recommendations for its application in assessing plaque morphology in ACS. In premenopausal women, intracoronary imaging is particularly beneficial in cases of myocardial infarction with non-obstructive coronary arteries (MINOCA) or when lesion morphology is uncertain and nonatherosclerotic causes are suspected. OCT is preferred over intravascular ultrasound for visualizing plaque rupture and erosion, and in women with MINOCA, multimodal imaging combining OCT and cardiac magnetic resonance imaging (cMRI) identified the pathogenesis of MINOCA in 85% of cases, with a definite or possible culprit lesion found in 46% of 145 patients in a multicenter study. The most frequently observed abnormalities on OCT included plaque rupture, intraplaque hemorrhage, and layered plaque, all indicative of plaque disruption. Additionally, when spontaneous coronary artery dissection (SCAD) is suspected but angiographic images are inconclusive, intracoronary imaging can assist in confirming the diagnosis. In such instances, the decision to utilize intracoronary imaging and the choice of imaging modalities should consider the operator's and center's experience, the risks associated with inadvertently wiring the false lumen, and the potential for dissection propagation or hydraulic expansion of the intramural hematoma.
Guidance of Percutaneous Coronary Interventions and Coronary Stent Implantation
In a randomized controlled trial (RCT), Ali and associates (2016) examined whether a novel OCT-based stent sizing strategy would result in a minimum stent area similar to or better than that achieved with IVUS guidance and better than that achieved with angiography guidance alone. These researchers recruited patients aged 18 years or older undergoing PCI from 29 hospitals in 8 countries. Eligible patients had one or more target lesions located in a native coronary artery with a visually estimated reference vessel diameter of 2.25 to 3.50 mm and a length of less than 40 mm. They excluded patients with left main or ostial right coronary artery stenoses, bypass graft stenoses, chronic total occlusions, planned 2-stent bifurcations, and in-stent restenosis. Participants were randomly assigned (1:1:1; using an interactive web-based system in block sizes of 3, stratified by site) to OCT guidance, IVUS guidance, or angiography-guided stent implantation. These investigators performed OCT-guided PCI using a specific protocol to establish stent length, diameter, and expansion according to reference segment external elastic lamina measurements. All patients underwent final OCT imaging (operators in the IVUS and angiography groups were masked to the OCT images). The primary efficacy endpoint was post-PCI minimum stent area, measured by OCT at a masked independent core laboratory at the completion of enrollment, in all randomly allocated participants who had primary outcome data. The primary safety endpoint was procedural major adverse cardiovascular events (MACE). These researchers tested the non-inferiority of OCT guidance to IVUS guidance (with a non-inferiority margin of 1.0 mm²), superiority of OCT guidance to angiography guidance, and superiority of OCT guidance to IVUS guidance, in a hierarchical manner. Between May 13, 2015, and April 5, 2016, these investigators randomly allocated 450 patients (158 [35%] to OCT, 146 [32%] to IVUS, and 146 [32%] to angiography), with 415 final OCT acquisitions analyzed for the primary endpoint (140 [34%] in the OCT group, 135 [33%] in the IVUS group, and 140 [34%] in the angiography group). The final median minimum stent area was 5.79 mm² (inter-quartile range [IQR] of 4.54 to 7.34) with OCT guidance, 5.89 mm² (4.67 to 7.80) with IVUS guidance, and 5.49 mm² (4.39 to 6.59) with angiography guidance. OCT guidance was non-inferior to IVUS guidance (1-sided 97.5% lower CI -0.70 mm²; p = 0.001), but not superior (p = 0.42). OCT guidance was also not superior to angiography guidance (p = 0.12). These researchers noted procedural MACE in 4 (3%) of 158 patients in the OCT group, 1 (1%) of 146 in the IVUS group, and 1 (1%) of 146 in the angiography group (OCT versus IVUS p = 0.37; OCT versus angiography p = 0.37). The authors concluded that OCT-guided PCI using a specific reference segment external elastic lamina-based stent optimization strategy was safe and resulted in a similar minimum stent area to that of IVUS-guided PCI. They stated that these findings warrant a large-scale randomized trial to establish whether or not OCT guidance results in superior clinical outcomes to angiography guidance.
In a systematic review, Jiang and colleagues (2019) examined the overall efficacy of OCT-guided implantation versus angiography-guided implantation for PCI. The following electronic databases, such as CENTRAL, PubMed, Cochrane, and Embase, were searched to investigate OCT-guided and angiography-guided implantation. These researchers measured the following seven parameters in each patient: stent thrombosis, cardiovascular death, myocardial infarction (MI), MACE, target lesion revascularization (TLR), target vessel revascularization (TVR), and all-cause death. A total of 11 studies (6 RCTs and 5 observational studies) involving 4,026 subjects were included, with 1,903 receiving IVUS-guided drug-eluting stent (DES) implantation and 2,123 using angiography-guided DES implantation. With regard to MACE, MI, TLR, TVR, stent thrombosis, and all-cause death, the group of OCT-guided implantation had no significant statistical association with remarkably improved clinical outcomes. However, its effect on cardiovascular death had a significant statistical difference in the angiography-guided implantation group. The authors concluded that in the present pooled analysis, OCT-guided DES implantation showed a tendency toward improved clinical outcomes compared to angiography-guided implantation. These researchers stated that more eligible randomized clinical trials are needed to verify the findings and to determine the beneficial effect of OCT guidance for patients.
Niu et al. (2022) noted that traditional angiography only displays 2D images of the coronary arteries during stent implantation; however, intravascular imaging can reveal the structure of the vascular wall and plaque characteristics. In a systematic review and meta-analysis, these investigators examined the effectiveness of intravascular imaging-guided drug-eluting stent (DES) implantation. They carried out a literature search of RCTs of intravascular imaging-guided procedures, including patients with DES implantation guided by intravascular ultrasound (IVUS) or OCT and traditional angiography. The databases of PubMed, Embase, Web of Science, and Cochrane Library were searched. The primary outcome was TLR. The secondary outcomes included TVR, myocardial infarction (MI), stent thrombosis (ST), cardiac death, all-cause death, and MACE during the 6 to 24 months follow-up. The fixed-effects model was used to calculate the relative risk (RR) and 95% confidence interval (CI) of the outcome event. This meta-analysis included 14 RCTs with 7,307 patients. Compared with angiography-guided procedures, intravascular imaging-guided DES implantation could significantly reduce the risk of TLR (RR 0.63, 95% CI: 0.49 to 0.82, p = 0.0004), TVR (RR 0.66, 95% CI: 0.52 to 0.85, p = 0.001), cardiac death (RR 0.58; 95% CI: 0.38 to 0.89; p = 0.01), MACE (RR 0.67, 95% CI: 0.57 to 0.79; p < 0.00001), and ST (RR 0.43, 95% CI: 0.24 to 0.78; p = 0.005). While there was no significant difference regarding MI (RR 0.77, 95% CI: 0.57 to 1.05, p = 0.10) and all-cause death (RR 0.87, 95% CI: 0.58 to 1.30, p = 0.50). The authors concluded that compared with traditional angiography, DES implantation guided by intravascular imaging could reduce the risk of TLR, TVR, cardiac death, MACE, and ST. Furthermore, patients with complex lesions would benefit more in terms of MACE. However, whether it is necessary to routinely use intravascular imaging to guide stent implantation still needs to be further examined.
The authors stated that this meta-analysis had several drawbacks. First, most of the included RCTs had small sample sizes, with a low incidence of positive events and wide CIs, which reduced the quality of evidence. Second, trial sequential analysis (TSA) showed that the outcomes of cardiac death, MI, and all-cause death need further investigation. Furthermore, the different definitions of MACE and MI in the included trials may be one of the reasons for the heterogeneity of MACE outcomes. MI did not yield a positive outcome. Meanwhile, MI and MACE were not used as the primary outcomes in this meta-analysis. Third, intravascular imaging described in this study included both IVUS and OCT. Additionally, this study included all types of DES; the new generation of DES may lead to better clinical outcomes. However, the subgroup analysis of the first or second generation and new-generation DES in this study did not yield a positive result, which may be related to insufficient sample size and the fact that different trials have been associated with different definitions of clinical outcomes. Thus, further investigation is needed on the relationship between different DES types and intravascular imaging types. Fourth, the underlying disease of patients, the location of lesions, the number of diseased vessels, and the specific treatment strategies may also affect the clinical outcome; however, this study was a study-level analysis, and further analysis could not be performed.
Hu et al. (2022) stated that coronary angiography (CAG) is the standard imaging modality for guiding PCI. Intra-coronary imaging techniques such as IVUS and OCT, as well as hemodynamic parameters like FFR, could overcome some limitations of CAG. In an updated systematic review and Bayesian network meta-analysis, these investigators examined the clinical outcomes of different PCI guidance modalities in the era of drug-eluting stents (DES). They carried out a network meta-analysis of 28 randomized trials and 11,860 patients undergoing different modalities-guided PCI in the era of DES; odds ratios (OR) with 95% confidence intervals (CIs) were calculated. In comparison with CAG, IVUS was associated with a significant reduction in MACE (OR: 0.60; 95% CI: 0.46 to 0.79), cardiovascular death (OR: 0.46; 95% CI: 0.20 to 0.94), TVR/TLR (OR: 0.55; 95% CI: 0.41 to 0.74), and a trend toward decreased risk of ST (OR: 0.44; 95% CI: 0.17 to 1.00). FFR/QFR could significantly reduce stroke compared with CAG, IVUS, and OCT/optical frequency domain imaging (OFDI); however, MI, all-cause death, ST, and any revascularization presented similar risks for different PCI guidance modalities. The authors concluded that this network meta-analysis provided evidence that IVUS-guided PCI resulted in less MACE, cardiovascular death, and TVR/TLR. FFR/QFR-guided PCI resulted in a decreased risk of stroke in the DES era. Moreover, these researchers stated that further studies are needed to validate the rationality of different modalities in guiding PCI in the era of DES.
The authors stated that this study had several drawbacks. First, this was a study-level meta-analysis providing average treatment effects. The absence of patient-level data prevented the authors from examining the effect of baseline clinical characteristics in PCI guidance modalities that might affect clinical outcomes. Second, subgroup analysis based on stable or acute coronary symptoms was impossible because both stable and acute coronary symptom patients were included in the same trial. However, the ADAPT-DES study revealed that IVUS-guided PCI was superior to CAG-guided PCI in both stable and acute coronary symptom patients. Third, just 6 studies (n = 4,214) in total reported 17 (0.40%) stroke events, which was too small in scale and may be the reason for the wide CI; thus, more randomized trials are needed to validate the rationality of different modalities in guiding PCI in the era of DES. Fourth, IVUS has been used clinically for almost 30 years, and extensive clinical experience has been gained. However, the same scenario has not been obtained for other PCI guidance modalities (OCT, OFDI, FFR, and QFR). Considering the fact that a long learning curve is needed to commend a new PCI guidance modality, unfamiliarity with the newly developed PCI guidance modality may negatively affect prognosis.
Siddiqi et al. (2022) stated that OCT is an adjunct to angiography-guided coronary stent placement; however, in the absence of dedicated, appropriately powered RCTs, the impact of OCT on clinical outcomes is unclear. In a systematic review and meta-analysis, these investigators examined all available studies comparing OCT-guided versus angiography-guided and intravascular ultrasound (IVUS)-guided coronary stent implantation. Medline and Cochrane Central were queried from their inception through July 2022 for all studies that sought to compare OCT-guided PCI to angiography-guided and IVUS-guided PCI. The primary endpoint was minimal stent area (MSA) compared between modalities. Clinical endpoints of interest were all-cause and cardiovascular mortality, MACE, MI, TLR, TVR, and ST. Mean differences (MDs) and relative risks (RRs) with their corresponding 95% CIs were pooled using a random-effects model. A total of 13 studies (8 RCTs and 5 observational studies) enrolling 6,312 participants were included. OCT was associated with a strong trend toward increased MSA compared to angiography (MD = 0.36, p = 0.06). OCT-guided PCI was also associated with a reduction in the incidence of all-cause mortality (RR = 0.59, 95% CI: 0.35 to 0.97, p = 0.04) and cardiovascular mortality (RR = 0.41, 95% CI: 0.21 to 0.80, p = 0.009) compared with angiography-guided PCI. Point estimates favored OCT relative to angiography in MACE (RR = 0.75, 95% CI: 0.47 to 1.20, p = 0.22) and MI (RR = 0.75, 95% CI: 0.53 to 1.07, p = 0.12). No differences were detected in ST (RR = 0.71, 95% CI: 0.21 to 2.44, p = 0.58), TLR (RR = 0.71, 95% CI: 0.17 to 3.05, p = 0.65), or TVR rates (RR = 0.89, 95% CI: 0.46 to 1.73, p = 0.73). Compared with IVUS guidance, OCT guidance was associated with a non-significant reduction in the MSA (MD = -0.16, p = 0.27). The rates of all-cause and cardiovascular mortality, MACE, MI, TLR, TVR, or ST were similar between OCT-guided and IVUS-guided PCI. The authors concluded that OCT-guided PCI was associated with reduced all-cause and cardiovascular mortality compared to angiography-guided PCI. Moreover, these researchers stated that these findings should be considered hypothesis-generating, as the mechanisms for the improved outcomes were unclear, and no differences were detected in the rates of TLR, TVR, or ST. OCT- and IVUS-guided PCI resulted in similar post-PCI outcomes. They stated that this hypothesis is being tested in the ongoing Ilumien IV Trial in the complex subset of coronary lesions and patients (NCT03507777).
The authors stated that this meta-analysis had several drawbacks. First, this meta-analysis was carried out under the assumption that the baseline characteristics of the patients in the included studies were similar. While discrepancies in patient characteristics and background therapies could have possibly contributed to clinical heterogeneity, a low statistical heterogeneity was noted in this study. Second, the timing of OCT assessment in the included studies was arbitrary and at relatively short follow-up times. OCT imaging at longer follow-up periods may provide additional information and detect clinically significant differences. Third, only 6 studies from the 13 included studies examined MSA, warranting more RCTs assessing MSA and its association with post-OCT outcomes. Fourth, the studies were limited by small sample sizes and non-randomized designs of the observational studies; although via subgroup analysis, these researchers attempted to differentiate the findings between the RCTs and observational studies.
The 2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline discusses the importance of intracoronary imaging in guiding coronary stent placement, particularly for complex lesions and the left main artery, leading to improved stent expansion, reduced malapposition, and fewer dissections. Intravascular ultrasound (IVUS) provides a comprehensive view of the vessel wall, allowing for the evaluation of plaque burden, calcification, lesion length, and external elastic lamina diameter before stent placement, as well as assessing minimum stent area, malapposition, underexpansion, tissue protrusion, edge disease, and edge dissection after deployment. Optical coherence tomography (OCT) uses infrared light to generate high-resolution images, offering specific advantages in assessing calcium thickness, lipid presence, thrombus formation, fibroatheroma, and plaque rupture, which is particularly useful in patients with acute coronary syndrome (ACS). Additionally, OCT is effective in examining stent strut neointimal thickness, apposition, and edge dissections, although it has limitations regarding imaging depth and requires contrast injection, which can restrict its use in ostial left main disease. Both IVUS and OCT are essential for evaluating lesion preparation, selecting appropriate stent sizes, minimizing geographical errors, confirming proper stent expansion, identifying complications, and understanding stent failure. Randomized trials have shown that intracoronary imaging guidance is associated with a lower risk of target vessel failure in patients undergoing percutaneous coronary intervention (PCI), with benefits extending to less complex lesions. The Renovate-Complex PCI trial demonstrated a significant reduction in target vessel failure with imaging guidance compared to angiographic guidance over a median follow-up of 2.1 years, while the OCTOBER trial showed similar benefits for bifurcation lesions. Although trials comparing OCT and IVUS indicate that OCT is noninferior to IVUS for PCI guidance, the ILUMIEN IV trial found no difference in target vessel failure rates with OCT in high-risk patients, though it did show a larger minimum stent area with OCT guidance and lower rates of stent thrombosis. A minimum stent area of less than 4.5 to 5.0 mm² by OCT is an independent predictor of major adverse cardiac events (MACE), and two large network meta-analyses confirm that intracoronary imaging guidance reduces cardiac death, target vessel myocardial infarction, target lesion revascularization, and stent thrombosis.
Assessment of Carotid Artery Stenosis / Stroke Risk
Blackham et al. (2015) noted that OCT is a modern intra-vascular imaging modality that has the capability to provide detailed, in-vivo characterization of the arterial wall and atherosclerotic plaque. The current understanding of the appearance of atherosclerotic plaque via OCT is largely based on coronary arterial studies where OCT information has been employed to guide therapeutic management and permits the immediate evaluation of PCI. The clinical success of OCT in the coronary arteries has laid the foundation for investigation of the carotid artery and thus, stroke risk assessment. The authors reported the novel use of OCT for tissue characterization of severe stenosis subsequent to carotid artery stenting, both before and after treatment with cutting balloon angioplasty.
An UpToDate review on “Evaluation of carotid artery stenosis” (Furie, 2015) does not mention optical coherence tomography as a diagnostic tool.
Assessment of Intermediate Coronary Lesions
Nogic and colleagues (2020) noted that intermediate coronary artery stenosis, defined as visual angiographic stenosis severity of between 30% to 70%, is present in up to one-fourth of patients undergoing coronary angiography. Patients with this particular lesion subset represent a distinct clinical challenge, with operators often uncertain about the need for revascularization. Although international guidelines appropriately recommend physiological pressure-based assessment of these lesions employing either fractional flow reserve (FFR) or quantitative flow ratio (QFR), there are specific clinical scenarios and lesion subsets where the use of such indices may not be reliable. Intravascular imaging, primarily intravascular ultrasound (US) and optical coherence tomography (OCT), represents an alternate and, at times, complementary diagnostic modality for the evaluation of intermediate coronary stenoses. Studies have attempted to validate these specific imaging measures with physiological markers of lesion-specific ischemia, with varied results. Intravascular imaging, however, also provides additional benefits that include portrayal of plaque morphology, guidance on stent implantation and sizing, and may portend improved clinical outcomes. The authors concluded that although invasive physiological assessment with FFR or instantaneous wave-free ratio (iFR) remains the current gold standard, a number of clinical scenarios may push clinicians toward assessment of lesion severity using intravascular imaging.
These researchers stated that moving forward, the future of OCT and IVUS assessment may lie in coupling with computational fluid dynamics (CFD) simulations of coronary flow and pressure. The use of CFD technology has the potential for clinicians to gather simultaneous anatomical and functional assessments of individual coronary lesions. However, several hurdles remain before this technology is more widely adopted. First, further validation work is needed in more diverse lesion and patient cohorts. Second, computational time for CFD is still relatively high, which precludes its use in a high-paced catheterization laboratory environment. Nevertheless, there is clear potential for the future, and there are several industry-led collaborations attempting to deliver this technology to clinicians soon.
Assessment of Intracranial Aneurysm
Hoffmann et al. (2016) stated that rupture risk assessment of an intracranial aneurysm (IA) is an important factor for indication of therapy. Until today, there is no suitable objective prediction method. Conventional imaging modalities cannot assess the IA's vessel wall. These researchers investigated the ability of intra-vascular OCT as a new tool for the characterization and evaluation of IAs. An experimental set-up for acquisition of geometrical aneurysm parameters was developed. Object of basic investigation was a silicone phantom with 6 IAs from patient data. For structural information, 3 circle of Willis were dissected and imaged post-mortem. All image data were post-processed by medical imaging software. Geometrical image data of a phantom with 6 different IAs were acquired. The geometrical image data showed a signal loss, e.g., in aneurysms with a high bottle-neck ratio. Imaging data of vessel specimens were evaluated with respect to structural information that is valuable for the characterization of IAs. Those included thin structures (intimal flaps), changes of the vessel wall morphology (intimal thickening, layers), adjacent vessels, small vessel outlets, arterial branches and histological information. The authors concluded that intra-vascular OCT provides new possibilities for diagnosis and rupture assessment of IAs. However, currently used imaging system parameters have to be adapted and new catheter techniques have to be developed for a complete assessment of the morphology of IAs.
Assessment of Pulmonary Arteries
Jorge and colleagues (2016) stated that along with the new interventional procedures being introduced for pulmonary vascular disease, there is an increasing need for intravascular imaging of the pulmonary arteries. Additionally, measurements of the wall thickness of the pulmonary arteries of patients with various types of pulmonary hypertension (PH) may provide relevant diagnostic and prognostic information. These investigators summarized all the available evidence on the use of optical coherence tomography (OCT) for imaging the pulmonary bed and described a simple protocol for OCT image acquisition. They conducted a systematic review of the literature using electronic reference databases through February 2015 (Medline, Cochrane Library, Web of Knowledge, and references cited in other studies) and the search terms "optical coherence tomography," "pulmonary hypertension," and "pulmonary arteries." Studies in which OCT was used to image the pulmonary vessels were considered for inclusion. They identified 14 studies reporting OCT imaging data from the pulmonary arteries; OCT was able to identify intravascular thrombi in patients with chronic thromboembolic PH (CTEPH), and an increase in vessel wall thickness was found in most patients with PH compared with the controls. Optical coherence tomography has also been reported to be useful for the selection of balloon size in the setting of balloon pulmonary angioplasty for CTEPH. The main drawbacks of this approach were lack of standardization, little data on outcomes, cost, and the technical limitations involved in visualizing small-diameter (less than 1 mm) pulmonary vessels. The authors concluded that OCT has become a potential tool for the in vivo study of vascular changes in the pulmonary arteries and may provide additional information in the assessment of patients with PH. They stated that prospective high-quality studies assessing the safety, validity, and clinical impact of OCT imaging for pulmonary vessels are needed.
Sun et al. (2022) noted that OCT is a high-resolution intravascular imaging tool and has shown promise for providing real-time quantitative and qualitative descriptions of pulmonary vascular structures in vivo in adult pulmonary hypertension (PH), while it is not as popular in pediatric patients with congenital heart diseases (CHD). In a systematic review, these investigators examined the available evidence on the use of OCT for imaging pulmonary vascular remodeling in pediatric patients. They carried out a review of the available evidence using the Cochrane Library database, Medline via PubMed, Embase, and Web of Knowledge from January 2010 to December 2021; the search terms included "PH," "child," "children," "pediatric," "OCT," "CHD," "pulmonary vessels," and "pulmonary artery wall." Studies in which OCT was used to image the pulmonary vessels in pediatric patients with CHD were considered for inclusion. A total of 5 studies met the inclusion criteria. These 5 studies discussed the use of OCT in the pulmonary vasculature of different types of CHD, including common simple CHD, complex cyanotic CHD, and Williams-Beuren syndrome. In bi-ventricular anatomy, pulmonary vascular remodeling was primarily reflected by pulmonary intima thickening from 2D-OCT. In single-ventricle anatomy, due to the state of hypoxia, the morphology of pulmonary vessels was indirectly reflected by the number and shape of nourishing vessels from 3D-OCT. The authors concluded that OCT has become a promising tool for the in vivo study of pulmonary artery morphology and may provide additional information in the assessment of pediatric patients with CHD. Moreover, these researchers stated that further prospective, high-quality studies are needed to confirm the safety, validity, and clinical impact of OCT imaging to evaluate pulmonary vascular structures in pediatric patients.
The authors stated that the potential applications for OCT imaging of the pulmonary vessels may include evaluating progression, assessing response to medical therapy, predicting prognosis, and guiding medical decision-making during follow-up. OCT is an emerging tool for guiding clinical practice, and the technology still needs to be improved to obtain higher frame rates and deeper penetration images. These investigators stated that OCT may be a useful tool to demonstrate the development of pulmonary artery vasa vasorum in pediatric patients with simple and complex CHD.
Detection of Coronary Vascular Changes Following Heart Transplantation
McGovern and colleagues (2019) described the initial findings from the International Pediatric Optical Coherence Tomography (OCT) registry in pediatric heart transplant recipients; OCT and angiography of the coronary arteries were performed in pediatric heart transplant recipients at participating centers. Demographics, clinical data, medications, episodes of rejection, and angiographically confirmed CAV were collected for each case; OCT and angiography images were analyzed in a central core imaging laboratory. Intimal thickness and intima/media cross sectional area (I/M CSA) ratios were calculated for each case. Intimal thickness of greater than or equal to 0.25 mm was defined as abnormal and greater than or equal to 0.4 mm as severe intima thickening; I/M CSA ratio of ≥1 was defined as abnormal. OCT findings were compared to angiographic findings for each case. Across 3 centers, a total of 110 cases were analyzed from 76 patients. Intimal thickening was present in 26 of 110 cases; 11 of these cases had severe intima thickening (greater than or equal to 0.4 mm) and notably, angiography results were normal in 8 cases. All 5 cases with a median I/M CSA ratio of greater than or equal to 2 had normal angiography. The maximal intima thickness was greater than or equal to 0.25 mm in 24% and greater than or equal to 0.4 mm in 10% of cases. Median I/M CSA ratio was greater than or equal to 1 for 80% of cases; I/M CSA ratio was significantly higher in cases with concurrent CAV (p = 0.03). Maximal intima thickness was significantly greater in cases with current or previous rejection (p = 0.01); I/M CSA ratio was significantly lower in patients treated with statins (p = 0.01). OCT findings alone prompted a change to medical management in 17% of cases. The authors concluded that OCT provided important insights into coronary vascular changes not detected by angiography in pediatric transplant recipients. Moreover, they stated that the use of OCT for pediatric heart transplant recipients should be further investigated, given its potential to impact the management of CAV.
Diagnosis of Pulmonary Artery Thrombus
Hong and co-workers (2018) stated that peripheral pulmonary artery thrombus (PPT) is common in clinical practice. However, due to the lack of an ideal diagnostic tool, PPT cannot be quickly diagnosed and effectively treated at present; optical coherence tomography (OCT) is a new intravascular imaging technique characterized by high image resolution. This technique is suitable for small vessel imaging and has the ability to distinguish between red and white thrombi. These researchers examined the value of OCT in the diagnosis of PPT and in identifying the nature of thrombi by comparing the sensitivity between OCT and selective pulmonary angiography (SPA). Highly suspected PPT patients were enrolled in this study. Pulmonary ventilation/perfusion (V/Q) mismatch pulmonary segments or peripheral pulmonary arteries were chosen; SPA was performed first, followed by OCT imaging. The diagnostic standard of thrombus with SPA was an intraluminal filling defect. The procedure and criteria for OCT diagnosis of thrombus were previously introduced in intra-coronary OCT thrombus images. The diameter of the imaging vessels was measured, and they were grouped according to diameter: less than 2 mm in the distal segment group, 2 to 3 mm in the middle segment group, and greater than 3 mm in the proximal segment group. The recognition abilities of intravascular thrombus with the different diameters of these two techniques were compared. Patients with obvious clinical symptoms and more red thromboses revealed by OCT were given standardized anticoagulant therapy for 6 months. The clinical symptoms, 6-minute walking test (6MWT), and changes in the thrombus in the OCT images of these patients before and after treatment were observed. A total of 22 patients with highly suspected PPT were suggested to undergo V/Q inspection. Finally, 12 patients were eligible for the study; SPA and OCT were performed in 61 peripheral pulmonary arteries in all 12 patients. The ideal SPA and OCT images obtained from a total of 76 blood vessel segments were suitable for comparative analysis. A total of 62 thrombi were found by SPA. Among these, 8 thrombi were in the distal segment, 29 thrombi were in the middle segment, and 25 thrombi were in the proximal segment. A total of 81 thrombi were found by OCT, among which 22 thrombi were in the distal segment, 31 were in the middle segment, and 28 were in the proximal segment. There was a significant difference between the two groups in the distal segment group (p = 0.013), while there was no significant difference between the two groups in the middle segment or the proximal segment groups (p > 0.05). In addition to all the thrombi found by SPA, OCT identified other thrombi that were missed by SPA. According to previous OCT images for determining the nature of thrombi, OCT revealed 81 thrombi, of which 48 (59%) were red thrombi and 33 (41%) were white thrombi. Then, 7 patients who had obvious clinical symptoms and more red thrombi in the peripheral pulmonary artery were given anticoagulant therapy for 6 months. After treatment, these symptoms improved, oxygenation indexes increased, and the 6MWT was extended in all these patients. After anticoagulation therapy, 5 patients underwent OCT review. These OCT images were matched and compared before and after anticoagulation therapy. The results revealed that most of the thrombi had disappeared, and a small amount of red thrombi turned white as the volume reduced. The mean lumen area before and after treatment was 2.05 ± 1.03 mm² and 2.86 ± 1.24 mm², respectively, and the difference was statistically significant (p = 0.035). The authors concluded that OCT could show the structure of the lumen and the wall of the peripheral pulmonary artery. The sensitivity of the diagnosis of PPT with a diameter of less than 2 mm was higher than that of SPA. Moreover, OCT had the ability to distinguish between red and white thrombi, which was of guiding significance in anticoagulant therapy.
The authors stated that this study had the same drawbacks as previous studies, namely, a lack of histopathological specimens corresponding to these OCT images. The main reason was that the risk of human peripheral lung biopsy was high, making it difficult for patients to accept. However, in the authors’ previous study, an intraluminal lesion specimen was obtained from one patient by aspiration; the OCT images revealed a red thrombus, which was confirmed by pathological examination. In addition, the study patients whose OCT images suggested a large number of red thrombi were given standardized anticoagulant therapy; OCT images were compared before and after treatment, and the results revealed that most of the lesions disappeared inside the lumen after treatment, which further demonstrated that the lesions shown by OCT images were thrombi. However, the number of cases included in this study was small, which could lead to possible bias. Next, these investigators hoped to obtain pulmonary artery OCT images and pathological specimens of fresh and old thrombi in animal experiments to study OCT images of different thrombi. Moreover, they hoped to conduct a multi-center cooperative study of the clinical value of OCT in peripheral pulmonary artery disease. They stated that OCT is a traumatic and time-consuming examination method. There are many peripheral pulmonary arteries in the human body; thus, most peripheral pulmonary artery OCT imaging could not be completed in a short period. Therefore, whether OCT is suitable for the diagnosis of PPT remains controversial.
Furthermore, an UpToDate review on “Clinical presentation, evaluation, and diagnosis of the nonpregnant adult with suspected acute pulmonary embolism” (Thompson et al., 2018) does not mention intravascular OCT as a diagnostic tool.
Evaluation of Arterial Bifurcations Covered by Flow Diverting Stents
Iosif and co-workers (2016) stated that due to its high spatial resolution, intravascular OCT has been used as a valid method for in-vivo evaluation of several types of coronary stents at straight lumen and bifurcation sites.These researchers evaluated its effectiveness for flow diverting stents deployed in arterial bifurcation sites involving jailing of a side branch. A total of 4 large white swine were stented with flow diverting stents covering the right common carotid artery-ascending pharyngeal artery bifurcation. After 12 weeks of follow-up the animals were evaluated by digital subtraction angiography and intravascular OCT and subsequently sacrificed. Neointimal thickness on the parent arteries and the free segments of the stent were measured. The stented arteries were harvested and underwent scanning electron microscopy (SEM) imaging. Ostia surface values were measured with OCT three-dimensional (3D) reconstructions and SEM images. All endovascular procedures and OCT pullback runs were feasible. Stent apposition was satisfactory on the immediate post-stent OCT reconstructions. At 12-week controls, all stents and jailed branches were patent. Mean neointimal thickness was 0.11 ± 0.04 mm on the free segments of the stent. The mean ostia surface at 12 weeks was 319,750 ± 345,533 μm2 with 3D-OCT reconstructions and 351,198 ± 396,355 μm2 with SEM image-derived calculations. Good correlation was found for ostia surface values between the 2 techniques; the values did not differ significantly in this preliminary study. The authors concluded that intravascular OCT appeared to be a promising technique for immediate and follow-up assessment of the orifice of arterial branches covered by flow diverting stents.
Evaluation of Coronary Stenosis in Individuals with Antiphospholipid Syndrome
Ito and Hasuo (2017) noted that intravascular images of coronary stenosis by anti-phospholipid syndrome (APS) would be beneficial to understand the mechanism of this disease. In a case-study, these investigators reported the findings of a 59-year old woman with APS/systemic lupus erythematosis (SLE) who underwent emergent coronary angiography that revealed stenosis with micro-channels in the proximal left anterior descending artery. According to OCT, the central lumen was surrounded by a thick septum with a homogenous and high intensity. Multiple small channels existed near the vessel wall with diffuse intimal hyperplasia. White thrombi were floating distal to the stenosis. Intravascular images obtained by OCT revealed the microstructure of complex coronary stenosis, which had ambiguous findings on angiography and IVUS in an ACS patient with APS/SLE. This was a single-case study; its findings need to be further investigated in well-designed studies with a larger sample size and longer follow-up (longer than 6 months).
Evaluation of Pulmonary Arterial Vasculopathy in Systemic Sclerosis
In a pilot study, Schwaiger and colleagues (2017) utilized optical coherence tomography (OCT) during right heart catheterization to compare the distal pulmonary vasculature, specifically vessels less than 2 mm in diameter, in patients with systemic sclerosis (SSc) who had pulmonary arterial hypertension (PAH) versus those who did not. The results indicated that patients with SSc-PAH exhibited a significant increase in intima-media thickness compared to their counterparts without PAH (27 ± 5.8% versus 21 ± 1.4%, p = 0.024). Additionally, a favorable hemodynamic response to prior targeted PAH treatment correlated with a higher number of small pulmonary artery side branches measuring less than 300 μm per cm of vessel (3.8 ± 1.1 versus 1.8 ± 1.1; p = 0.010), although this was not linked to the intima-media thickening area (26 ± 5.4% versus 28 ± 6.7%; p = 0.6). Notably, 19% of SSc-PAH patients exhibited unexpected evidence of pulmonary artery thrombus formation. This study was the first to demonstrate an in-vivo connection between structural abnormalities in pulmonary arteries and responses to targeted PAH treatment, suggesting that intravascular imaging could help identify subgroups that may benefit from anticoagulation. However, the study had limitations, including a small sample size (n = 17 for the OCT group), although the data's robustness was enhanced by ensuring a homogeneous study population by excluding potential confounders such as left heart abnormalities, significant lung pathology, and renal involvement. The study did not clarify whether responders to treatment had preserved small vessels for vasodilation or the capacity to develop new vessels in response to therapy, indicating a need for longitudinal studies. While one small longitudinal OCT study reported on pulmonary artery remodeling after treatment in early-stage PAH, it only assessed wall thickening in more proximal vessels (3 to 4 mm range). Furthermore, the researchers did not employ computerized algorithms for measuring vessel wall thickening due to challenges with significant eccentric and patchy thickening, which would require complex algorithms to define the degree of thickening accurately. Additionally, delineating the outer boundary toward the adventitia, particularly in PAH, proved difficult, making automatic measurements prone to error; thus, the investigators relied on manual measurements, accepting a degree of underestimation while minimizing the likelihood of overestimation.
Follow-Up Evaluation of Renal Arteries After Radiofrequency Catheter-Based Renal Denervation
Roleder and associates (2016) noted that OCT imaging at the time of renal denervation (RDN) showed that procedure might cause spasm, intimal injury or thrombus formation. These researchers evaluated the healing of renal arteries after RDN using OCT and renal angiography in long-term follow-up. Optical coherence tomography and renal angiography were performed in 12 patients (22 arteries) 18.41 ± 5.83 months after RNS. There were no adverse events or complications during the long-term follow-up. In 10 patients (83%), significant reductions of blood pressure was achieved without a change of the anti-hypertensive medications. These investigators demonstrated the presence of 26 areas of focal intimal thickening identified by OCT in 10 (83%) patients and in 14 (63%) arteries. The mean area of focal intimal thickening was 0.054 ± 0.033 mm(2). No vessel dissection, thrombus, intimal tear or acute vasospasm were observed during the OCT analysis. Also, the quantitative angiography analysis revealed a significant reduction of the minimal and proximal lumen diameters at follow-up as compared to measurements obtained before RDN. The authors concluded that renal arteries have a favorable "long-term" vessel healing response after RDN. Focal intimal thickening and a modest reduction of the minimal lumen diameter may be observed after RF denervation. They stated that further studies are needed to determine whether intravascular imaging may be helpful in evaluating the vessel healing of RF RDN.
Guidance of Percutaneous treatment of Coronary Bifurcation Disease
Wolfrum and colleagues (2017) noted that cardiovascular disease remains the most common cause of death worldwide. Enormous progress in the technology and applicability of percutaneous techniques to treat obstructive coronary heart disease has been made, and the number of PCIs is increasing. Coronary bifurcations are involved in a substantial number of PCIs, and despite recent advances, bifurcation PCI remains a challenge in terms of immediate success and long-term outcomes. Angiography has a limited capacity for showing important features of the 3-D coronary vessel anatomy, the position of stent struts, and exact wire positions, and is therefore suboptimal for guiding bifurcation PCI. Intracoronary OCT provides high resolution, and the information gained during PCI is unprecedented compared with angiography guidance and IVUS. These investigators provided an overview of the use of OCT to guide bifurcation PCI. The authors concluded that OCT is a promising guide for bifurcation PCI at each individual step: from planning the strategy (provisional versus 2-stent strategy) to guidance during PCI, and finally checking the interventional result.
In a review on “Intravascular optical coherence tomography,” Bouma and associates (2017) described the driving considerations of the clinical application of intravascular OCT and its constraints, the major engineering milestones that enabled the current high-performance commercial imaging systems, the key studies that laid the groundwork for image interpretation, and the clinical research that traces intravascular OCT from early human pilot studies to current clinical trials. The authors concluded that considering the unique capabilities of OCT, the progress that has been made to date with developing, validating, commercializing, and disseminating intravascular systems, and the advances with its utilization as a powerful research tool for investigating coronary atherosclerosis and the response of disease to intervention, as well as its potential role in routinely guiding interventions, it is clear that this technology will continue to make a significant impact in cardiology.
In summary, there is currently insufficient evidence to support a predictive role for intravascular OCT for the assessment of cardiovascular risk or in catheter-based interventions or follow-up evaluations. Prospective, randomized trials are needed to ascertain the clinical value of this emerging imaging technology.
Intravascular Imaging of Cerebral Vessels
Anagnostakou et al. (2021) stated that the diagnosis of cerebrovascular disease includes vascular neuroimaging techniques such as computed tomography angiography (CTA), magnetic resonance angiography (MRA, with or without the use of contrast agents), and catheter digital subtraction angiography (DSA). These techniques primarily provide information regarding the vessel lumen. Vessel wall imaging with MRI seeks to characterize cerebrovascular pathology but often lacks the resolution needed for small lesions. Intravascular imaging techniques such as ultrasound (US) and optical coherence tomography (OCT), which have been used for over 10 years in the peripheral circulation, are not amenable to routine deployment in the intracranial circulation due to vessel caliber and tortuosity. However, advances in OCT technology, including improvements in probe profile, stiffness, and unique distal rotation solutions, hold promise for the eventual translation of OCT into the clinical arena.
Wang et al. (2023) noted that intravascular OCT (IV-OCT) is important for assessing lumen dimensions and guiding interventional procedures; however, traditional catheter-based IV-OCT faces challenges in achieving precise and full-field 360° imaging in tortuous vessels. Current IV-OCT catheters that use proximal actuators and torque coils are susceptible to non-uniform rotational distortion (NURD) in tortuous vessels, while distal micromotor-driven catheters struggle with complete 360° imaging due to wiring artifacts. These researchers developed a miniature optical scanning probe with an integrated piezoelectric-driven fiber optic slip ring (FOSR) to facilitate smooth navigation and precise imaging within tortuous vessels. The FOSR features a coil spring-wrapped optical lens serving as a rotor, enabling efficient 360° optical scanning. The structurally and functionally integrated design significantly streamlined the probe (with a diameter of 0.85 mm and a length of 7 mm) while maintaining an excellent rotational speed of 10,000 rpm. High-precision 3D printing technology ensures accurate optical alignment of the fiber and lens inside the FOSR, with a maximum insertion loss variation of 2.67 dB during probe rotation. Lastly, a vascular model revealed smooth probe insertion into the carotid artery, and imaging of oak leaf, metal rod phantoms, and ex vivo porcine vessels verified its capabilities for precise optical scanning, comprehensive 360° imaging, and artifact elimination. The authors concluded that the FOSR probe exhibited a small size, rapid rotation, and optical precision scanning, rendering it exceptionally promising for cutting-edge intravascular optical imaging techniques.
Mansourian et al. (2024) stated that endovascular management of intracranial aneurysms (IA) has become the mainstay of treatment in recent years; however, re-treatment rates remain as high as 20%. High-frequency OCT (HF-OCT) is an emerging imaging modality for the assessment, treatment, and follow-up of cerebral aneurysms. Embase and SCOPUS databases were searched for studies relating to the management of IA with OCT. A combination of keywords was employed, including “cerebral aneurysm,” “intracranial aneurysm,” “high-frequency optical coherence tomography,” “optical coherence tomography,” and “optical frequency domain imaging.” A total of 23 studies were included in this review. For the assessment of IA, OCT was able to accurately examine aneurysm morphology as well as provide a detailed analysis of arterial wall layers. During IA treatment, OCT was used to assess and troubleshoot stent placement to optimize successful isolation from the circulation. In the follow-up period, endothelial growth patterns were visualized by OCT imaging. The authors concluded that OCT showed promise for the treatment of IAs at all stages of management. Due to the novel development of HF-OCT, there is limited longitudinal data in human studies. These researchers stated that further investigations in this field are needed, focusing specifically on long-term treatment outcomes in humans.
Jung et al. (2025) noted that OCT has been extensively used in cardiovascular diagnostics due to its high resolution and rapid imaging capabilities; however, its adaptation for cerebrovascular applications remains constrained by the narrow, tortuous anatomical structure of cerebral vessels. To address these limitations, these researchers introduced a cerebrovascular-specific OCT (bOCT) catheter, an advanced adaptation of the cardiovascular OCT (cOCT) catheter, with significant structural modifications for improved access to cerebral blood vessels. The bOCT catheter entails a braided wire within a braided tube, strategically reinforcing axial strength. The distal shaft was reconfigured as a single-lumen structure, facilitating unified movement of the rotating fiber optic core and guide wire, thus reducing guide wire bending and augmenting force transmission stability. Furthermore, the anterior protrusion was removed and replaced with a dual-lumen configuration, significantly enhancing lesion accessibility. The bOCT catheter's performance was validated in a 3D physical model and an animal model, showing pronounced enhancements in flexibility, pushability, and navigability. Notably, the pushability via curved flow paths significantly improved, enhancing access to cerebral blood vessels. The authors concluded that this innovation promises to revolutionize cerebrovascular diagnostics with high-resolution imaging suited to the complex brain vasculature, setting a new standard in intravascular imaging technology.
The authors stated that this study had several drawbacks, especially emphasizing the development of a bOCT catheter aimed at enhancing trackability and pushability to traverse tortuous vessels. As a result, comprehensive evaluation of the catheter’s function was not prioritized. Moreover, the bOCT catheter was tested mainly in controlled and animal models, which may not entirely reflect the complexity and variability of human cerebrovascular structures, potentially affecting its applicability in clinical settings. Additionally, the catheter’s long-term durability and performance under continuous use remain unverified. Future studies will focus on enhancing the clinical feasibility of the bOCT catheter through biocompatibility assessments, accelerated aging studies, and pre-clinical studies to examine its long-term usability, thrombotic response, and structural integrity. To further validate its mechanical advantages, additional axial load-bearing tests will provide deeper insights into its mechanical durability. Future studies will also examine the catheter’s usability by incorporating a broader range of pre-clinical models, including larger animal studies with complex vascular structures, to assess trackability, pushability, and imaging precision across varied cerebrovascular environments. Furthermore, comparative analyses with existing neurovascular devices will aid in refining its design, functional optimization, and clinical applicability. The catheter’s impact on blood flow dynamics and vessel wall interactions will also be examined via computational fluid dynamics (CFD) simulations and in vivo imaging studies, evaluating shear stress alterations, hemodynamic flow patterns, and endothelial responses to ensure minimal vascular trauma during navigation. In addition, a quantitative assessment of the OCT image quality, including the signal-to-noise ratio, axial resolution, and imaging consistency, will be carried out using phantom and in vivo imaging experiments to validate its diagnostic performance in different vascular conditions. Collectively, these investigations will refine the optimization and broader applicability of the bOCT catheter for advanced neurovascular interventions.
Tang et al. (2025) stated that frequency-domain OCT (FD-OCT) is an emerging intravascular imaging modality that offers exceptional spatial resolution in interventional neuroradiology. In a systematic review, these investigators examined clinical studies on the applications of FD-OCT in cerebral large artery atherosclerosis (LAA). They conducted a systematic literature review of PubMed, Embase, and the Cochrane Library to identify eligible studies published before March 1, 2025. Eligible studies included all clinical articles written in English that reported the applications of FD-OCT in patients diagnosed with LAA. A total of 50 studies with 1,134 patients were included. FD-OCT was considered a feasible intravascular imaging modality, as successful imaging could be achieved in 87.0% of patients with a 1.2% peri-procedural complication rate. Unsuccessful FD-OCT imaging was primarily attributed to its current limitations, especially inadequate blood clearance and failure to navigate the tortuous cerebrovascular anatomy or stenosis. The majority of the included studies (35/50) employed FD-OCT to assess extracranial atherosclerotic stenosis. FD-OCT could better stratify subsequent stroke risk by adequately identifying features of plaque vulnerability, such as thin-cap fibroatheroma, neovascularization, and cholesterol crystals. By accurately assessing stent-vessel interaction, FD-OCT has the potential to guide the selection of tailored interventions during carotid artery stenting. Recent research (10/50) has shown its potential use for intracranial atherosclerotic stenosis, including culprit lesion differentiation, peri-intervention evaluation, and mechanistic insight into the pathophysiology of stenosis and in-stent restenosis (ISR). As for acute ischemic stroke, FD-OCT following thrombectomy can potentially guide the selection of tailored adjunctive treatments to optimize clinical outcomes by assessing the intrinsic properties of the culprit lesion. The authors concluded that FD-OCT has emerged as a valuable intravascular imaging tool for assessing the intrinsic properties of culprit lesions and stent-vessel interactions, demonstrating substantial potential in the diagnosis, evaluation, and treatment of cerebral LAA.
Intravascular OCT-Guided Percutaneous Coronary Intervention in Patients with ST-Segment Elevation Myocardial Infarction (STEMI)
Yonetsu et al. (2023) stated that even after successful revascularization with percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI), subsequent adverse events (AEs) still occur. Previous studies have suggested potential benefits of intravascular imaging, including optical coherence tomography (OCT); however, the feasibility of OCT-guided primary PCI (pPCI) has not been systematically evaluated in these patients. The ATLAS-OCT (ST-elevation Acute Myocardial Infarction and Clinical Outcomes Treated by Optical Coherence Tomography-guided Percutaneous Coronary Intervention) Trial was designed to examine the feasibility of OCT guidance during pPCI for STEMI in experienced centers with expertise in OCT-guided PCI as a prospective, multicenter registry of consecutive patients with STEMI who underwent pPCI. The inclusion criteria for the centers were as follows: first, acute care hospitals providing 24/7 emergency care for STEMI; second, institutions where OCT-guided PCI is the first choice for pPCI in STEMI. All patients with STEMI who underwent pPCI at participating centers will be consecutively enrolled, irrespective of OCT use during PCI. The primary endpoint will be the rate of successful OCT imaging during pPCI. As an ancillary imaging modality to angiography, OCT provides morphologic information during PCI for the assessment of plaque phenotypes, vessel sizing, and PCI optimization. Major adverse cardiovascular events (MACE), defined as a composite of all-cause death, myocardial infarction (MI), and target vessel revascularization (TVR) at 1 year, will also be recorded. The authors stated that the ATLAS-OCT Trial will clarify the feasibility of OCT-guided pPCI for patients with STEMI and further identify a suitable patient group for OCT-guided pPCI.
Karamasis et al. (2023) noted that intracoronary imaging (ICI) modalities, namely intravascular ultrasound (IVUS) and OCT, have been shown to reduce MACE in patients undergoing PCI. However, patients with STEMI have been practically excluded from contemporary large randomized controlled trials (RCTs). The available data are limited and primarily derived from observational studies. Nevertheless, contemporary studies favor ICI utilization in patients who undergo pPCI. Regarding the technical aspects of PCI, ICI has been associated with the implantation of larger stent diameters, higher balloon inflations, and lower residual in-stent stenosis post-PCI. Although OCT is used significantly less often than IVUS, it is a useful tool in the context of myocardial infarction (MI) without obstructive coronary artery disease (CAD) since, due to its high spatial resolution, it can identify the underlying mechanism of STEMI and thus guide therapy. Stent thrombosis (ST) is a rare but potentially lethal complication that is clinically expressed as STEMI in the vast majority of cases. The use of ICI is encouraged by current guidelines to discriminate the mechanism of ST among stent malapposition, under-expansion, uncovered stent struts, edge dissections, ruptured neo-atherosclerotic lesions, and coronary evaginations. The authors concluded that the use of ICI in the context of STEMI and pPCI appears to have potential benefits on clinical outcomes; however, the data are limited and derived mostly from observational studies. Therefore, STEMI-dedicated, large-scale RCTs are needed to determine the optimal use of ICI in these high-risk patients.
Fang et al. (2024) stated that PCI with angiography guidance is a common procedure, and OCT is a non-invasive imaging method that uses light waves. In a retrospective cohort single-center study, these researchers compared 1-year outcomes in 75 patients with acute STEMI who underwent OCT-guided pPCI with 163 patients with acute STEMI who underwent PCI without OCT guidance. Patients with acute STEMI were enrolled from February 2019 to July 2021; a total of 75 patients underwent OCT-guided PCI (OCT group), while 163 underwent PCI without OCT (control group). Baseline characteristics, in-hospital mortality, target lesion revascularization (TLR), post-MI heart failure (HF), and 1-year all-cause mortality were compared between groups. The OCT group had lower prevalence rates of diabetes mellitus (DM) and hyperlipidemia. Furthermore, they experienced longer procedures (OCT: 50.45 ± 21.75 mins; control: 33.80 ± 14.44 mins; p < 0.001). After PCI, the control group had lower left ventricular ejection fractions (LVEF) (OCT: 53.4% ± 10.5%; control: 47.8% ± 12.4%; p < 0.001) and higher post-MI HF rates (OCT: 2.7%; control: 11.0%; p = 0.030). Notably, the 1-year all-cause mortality rate was significantly lower in the OCT group (OCT: 1.3%; control: 8.0%; p = 0.043). The authors concluded that during the 1-year follow-up, patients who received OCT-guided pPCI experienced a notably lower rate of post-MI HF than those who underwent pPCI without OCT guidance. These investigators noted that, more importantly, the use of OCT in pPCI procedures did not result in a higher incidence of distal embolism, even in cases with a significant thrombus burden.
The authors stated that this study had several drawbacks. First, it is crucial to acknowledge that this study was conducted as a retrospective cohort study and did not incorporate randomization to reduce potential bias. Potential confounders influenced the study’s results and conclusions. Second, this trial was limited by a relatively small number of enrolled patients (n = 75 in the OCT-guided group) and the exclusion of individuals requiring extracorporeal membrane oxygenation (ECMO) or intra-aortic balloon pump (IABP) support. Third, the analysis could not establish a correlation between OCT findings and clinical outcomes due to the limited number of clinical events observed in the OCT group. Fourth, it may be beneficial to include a group undergoing IVUS-guided PCI to compare results, which could aid in highlighting the differences and potential advantages of OCT-guided PCI.
He et al. (2024) noted that compared with IVUS guidance, there is limited evidence for OCT guidance during pPCI in STEMI patients. In an observational study, these investigators examined the role of OCT in guiding a reperfusion strategy and improving the long-term prognosis of STEMI patients. All participants diagnosed with STEMI who underwent pPCI between January 2017 and December 2020 were enrolled and divided into OCT-guided versus angiography-guided cohorts. They had routine follow-up for up to 5 years or until the time of the last known contact. All-cause death and cardiovascular (CV) death were designated as the primary and secondary endpoints, respectively. A total of 3,897 patients were enrolled: 2,696 (69.2%) with OCT guidance and 1,201 (30.8%) with angiographic guidance. Subjects in the OCT-guided cohort were less often treated with stenting during pPCI (62.6% versus 80.2%; p < 0.001). The 5-year cumulative rates of all-cause mortality and CV mortality in the OCT-guided cohort were 10.4% and 8.0%, respectively, significantly lower than in the angiography-guided cohort (19.0% and 14.1%; both log-rank p < 0.001). All four multivariate models showed that OCT guidance could significantly reduce 5-year all-cause mortality (HR in model 4: 0.689, 95% CI: 0.551 to 0.862) and CV mortality (HR in model 4: 0.692, 95% CI: 0.536 to 0.895). After propensity score matching, the benefits of OCT guidance were consistent in terms of all-cause mortality (HR: 0.707, 95% CI: 0.548 to 0.913) and CV mortality (HR: 0.709, 95% CI: 0.526 to 0.955). The authors concluded that compared with angiography alone, OCT guidance may change reperfusion strategies and result in better long-term survival in STEMI patients undergoing pPCI. Moreover, these researchers stated that results from this observational study should be further corroborated in randomized trials.
In a narrative review, Buonpane et al. (2024) emphasizes that coronary artery disease (CAD) remains a significant global health issue, with acute myocardial infarction (AMI) being one of its most common manifestations. Despite the widespread use of invasive treatment strategies, certain patient populations still face a higher risk of subsequent cardiovascular events. As a result, extensive research has been dedicated to identifying new risk factors and improving diagnostic, pharmacological, and invasive interventions for AMI. Coronary angiography is typically the first diagnostic tool used in AMI cases, facilitating revascularization and stenting of affected coronary arteries. However, while angiography has long been regarded as the gold standard for assessing CAD, it falls short in providing insights into plaque composition and biological activity. As a two-dimensional representation of a three-dimensional vascular structure, angiography is inadequate for accurately characterizing plaque, vessel walls, and lumen metrics, particularly in complex lesions where procedural success may not meet expectations. Even after successful revascularization, patients remain at risk for recurrent AMI, heart failure, and stent thrombosis, highlighting the need for improved coronary revascularization strategies. In this context, intravascular imaging has emerged as a crucial tool, enhancing clinical outcomes through precise evaluation of coronary vessels, particularly in AMI patients. Advanced imaging modalities such as intravascular ultrasound (IVUS), near-infrared spectroscopy IVUS (NIRS-IVUS), and optical coherence tomography (OCT) offer distinct advantages in visualizing and assessing the lumen, vessel structure, and atherosclerotic plaque phenotypes. IVUS provides comprehensive pre-intervention data on lesion characteristics, while OCT offers exceptional resolution for detailed assessment of plaque phenotypes and post-intervention information regarding stent expansion and apposition. Both techniques have demonstrated their utility in identifying the underlying mechanisms of coronary thrombosis, including plaque rupture, erosion, and calcified nodules, which are often overlooked in traditional angiography. Recent studies suggest that OCT can guide tailored therapeutic strategies based on specific plaque phenotypes in AMI patients, potentially improving clinical outcomes. Additionally, OCT plays a vital role in guiding percutaneous coronary intervention (PCI) by enabling effective lesion preparation, precise stent sizing, and verification of adequate stent expansion, thereby reducing the risks of stent thrombosis and in-stent restenosis. This narrative review underscores the importance of OCT in managing AMI, highlighting its dual function as an advanced diagnostic tool and a precise guide for PCI, ultimately aiming to optimize therapeutic strategies and improve clinical outcomes for patients with AMI.
Management of Acute Coronary Syndrome Caused by Plaque Erosion
Jia and colleagues (2018) noted that for several decades, most physicians have believed that acute coronary syndrome (ACS) is caused by coronary thrombosis resulting from the rupture of vulnerable plaques, which are characterized by a thin fibrous cap overlying a large necrotic core and significant inflammatory cell infiltration. However, nearly one-third of ACS cases are attributed to plaque erosion (PE), which is characterized by an intact fibrous cap, a smaller or absent necrotic core, reduced inflammation, and a larger lumen. Due to the limitations of current imaging modalities, including angiography and intravascular ultrasound (IVUS), the significance of PE as a cause of ACS is less well recognized. Optical coherence tomography (OCT), as an emerging modality with extremely high resolution, is the only intravascular imaging technique available for the in-vivo identification of PE, providing new insights into the mechanisms of ACS. More importantly, the introduction of OCT into clinical practice allows researchers to differentiate patients with ACS caused by PE from those caused by plaque rupture, thereby enabling precise and personalized therapy based on the different underlying mechanisms. The authors systematically reviewed the morphological characteristics of PE identified by OCT and its implications for the management of ACS.
Kim et al. (2024) noted that ACS frequently results from the rupture or erosion of high-risk coronary atherosclerotic plaques, commonly referred to as vulnerable plaques. Advances in intracoronary imaging techniques such as IVUS, OCT, and near-infrared spectroscopy (NIRS) have improved the identification of vulnerable plaques, which are characterized by a large plaque burden, a small minimal luminal area, a thin fibrous cap, and a high lipid content. Although pharmacotherapies, including lipid-lowering agents and intensive risk-factor control, are crucial for managing vulnerable plaques and preventing secondary events, recurrent incidents tend to occur despite intensive pharmacotherapy. Consequently, it has been hypothesized that local preventive PCI may help stabilize these vulnerable plaques, thereby preventing the occurrence of plaque-related ACS. However, solid evidence supporting its use for the treatment of non-flow-limiting vulnerable plaques is lacking, and as such, the optimal management of vulnerable plaques has not yet been established.
Prediction of Periprocedural Myocardial Injury in Persons with Stable Angina Pectoris
Kimura et al. (2015) stated that periprocedural myocardial injury (PMI) is not an uncommon complication and is related to adverse cardiac events after PCI. These researchers investigated the predictors of PMI in patients with stable angina pectoris (SAP) on intra-vascular imaging. They enrolled 193 SAP patients who underwent pre-PCI IVUS and OCT. Clinical characteristics, lesion morphology, and long-term follow-up data were compared between patients with and without PMI, defined as post-PCI elevation of high-sensitivity cardiac troponin-T. Periprocedural myocardial injuries were observed in 79 patients (40.9%). Estimated glomerular filtration rate (OR, 0.973; 95% CI: 0.950 to 0.996; p = 0.020), greater than or equal to 2 stents (OR, 3.100; 95% CI: 1.334 to 7.205; p = 0.009), final myocardial blush grade 0 to 2 (OR, 4.077; 95% CI: 1.295 to 12.839; p = 0.016), and IVUS-identified echo-attenuated plaque (EA; OR, 3.623; 95% CI: 1.700 to 7.721; p < 0.001) and OCT –TCFA(OR, 3.406; 95% CI: 1.307 to 8.872; p = 0.012) were independent predictors of PMI on multi-variate logistic regression analysis. A combination of EA and OCT-TCFA had an 82.4% positive predictive value (PPV) for PMI. On Cox proportional hazards analysis, PMI was an independent predictor of adverse cardiac events during 1-year follow-up (hazard ratio [HR], 2.984; 95% CI: 1.209 to 7.361; p = 0.018). The authors concluded that plaque morphology assessment using pre-PCI IVUS and OCT may be useful for predicting PMI in SAP patients.
Use during Percutaneous Coronary Intervention with Orbital Atherectomy
In a retrospective, multi-center registry, Lee and associates (2018) evaluated the impact of IVUS/ OCT on outcomes of patients who underwent orbital atherectomy. Of the 458 consecutive real-world patients in a total of 138 patients (30.1%) underwent orbital atherectomy with IVUS/OCT. The primary safety end-point was the rate of 30-day major adverse cardiac and cerebrovascular events, comprised of death, MI, target-vessel revascularization (TVR), and stroke. The IVUS/OCT group and no-imaging group had similar rates of the primary end-point (1.5% versus 2.5%; p = 0.48) as well as death (1.5% versus 1.3%; p = 0.86), MI (1.5% versus 0.9%; p = 0.63), TVR (0% versus 0%; p = NS), and stroke (0.0% versus 0.3%; p = 0.51). The 30-day stent thrombosis rates were low in both groups (0.7% versus 0.9%; p = 0.82). Emergent coronary artery bypass graft surgery was uncommonly performed in both groups (0.0% versus 0.9%; p = 0.25). The authors concluded that orbital atherectomy guided by intravascular imaging was safe and feasible. Moreover, they stated that a large prospective randomized trial is needed to determine the clinical benefit of IVUS/OCT during PCI with orbital atherectomy.
References
The above policy is based on the following references:
- Ali ZA, Maehara A, Généreux P, et al; ILUMIEN III: OPTIMIZE PCI Investigators. Optical coherence tomography compared with intravascular ultrasound and with angiography to guide coronary stent implantation (ILUMIEN III: OPTIMIZE PCI): A randomised controlled trial. Lancet. 2016;388(10060):2618-2628.
- Anagnostakou V, Ughi GJ, Puri AS, Gounis MJ. Optical coherence tomography for neurovascular disorders. Neuroscience. 2021;474:134-144.
- Bezerra HG, Costa MA, Guagliumi G, et al. Intracoronary optical coherence tomography: A comprehensive review clinical and research applications. JACC Cardiovasc Interv. 2009;2(11):1035-1046.
- Blackham KA, Kim BS, Jung RS, et al. In vivo characterization of carotid neointimal hyperplasia by use of optical coherence tomography: Before and after cutting balloon angioplasty. J Neuroimaging. 2015;25(6):1044-1046.
- Bouma BE, Villiger M, Otsuka K, Oh WY. Intravascular optical coherence tomography [Invited]. Biomed Opt Express. 2017;8(5):2660-2686.
- Buonpane A, Trimarchi G, Ciardetti M, et al. Optical coherence tomography in myocardial infarction management: Enhancing precision in percutaneous coronary intervention. J Clin Med. 2024;13(19):5791.
- Cambon A, Schiano P, Barbou F,et al.Optical coherence tomography applied to vessels: A bright future. Ann Cardiol Angeiol (Paris).2011;60(6):347-353.
- Di Mario C, Moreno PR. Invasive coronary imaging: Any role in primary and secondary prevention? Eur Heart J. 2016;37(24):1883-1890.
- Domingo E, Grignola JC, Aguilar R, et al. In vivo assessment of pulmonary arterial wall fibrosis by intravascular optical coherence tomography in pulmonary arterial hypertension: A new prognostic marker of adverse clinical follow-up. Open Respir Med J. 2013;7:26-32.
- Elmariah S, Jang I-K. Is optical coherence tomography effective in imaging intravascular thrombus? Cardiac Interventions Today, August 2011. Available at: http://bmctoday.net/citoday/2011/08/article.asp?f=is-optical-coherence-tomography-effective-in-imaging-intravascular-thrombus. Accessed February 29, 2012.
- Fang Y-N, Lee W-C, Chen C-J, et al. One-year clinical outcomes in acute ST-segment elevation myocardial infarction patients undergoing optical coherence tomography-guided primary percutaneous coronary intervention: A comparative study. Med Sci Monit. 2024;:30:e943298.
- Furie KL. Evaluation of carotid artery stenosis. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2015.
- Gonzalo N, Escaned J, Alfonso F, et al. Morphometric assessment of coronary stenosis relevance with optical coherence tomography: A comparison with fractional flow reserve and intravascular ultrasound. J Am Coll Cardiol. 2012;59(12):1080-1089.
- Gutierrez-Chico JL, Alegría-Barrero E, Teijeiro-Mestre R, et al. Optical coherence tomography: From research to practice. Eur Heart J Cardiovasc Imaging. 2012;13(5):370-384.
- He L, Hu S, Zhao C, et al. Five-year follow-up of OCT-guided percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction. EuroIntervention. 2024;20(15):e937-e947.
- Hoffmann T, Glaber S, Boese A, et al. Experimental investigation of intravascular OCT for imaging of intracranial aneurysms. Int J Comput Assist Radiol Surg. 2016;11(2):231-241.
- Hong C, Luo FQ, Liu CL, et al. Clinical study of optical coherence tomography in the diagnosis of peripheral pulmonary artery thrombus. Thromb Res. 2018;161:52-59.
- Hu M-J, Tan J-S, Yin L, et al. Clinical outcomes following hemodynamic parameter or intravascular imaging-guided percutaneous coronary intervention in the era of drug-eluting stents: An updated systematic review and Bayesian network meta-analysis of 28 randomized trials and 11,860 patients. Front Cardiovasc Med. 2022;9:860189.
- Iosif C, Saleme S, Ponsonnard S, et al. Intravascular optical coherence tomography for the evaluation of arterial bifurcations covered by flow diverters. J Neurointerv Surg. 2016;8:1283-1287.
- Ito S, Hasuo T. Intravascular images of coronary stenosis with multiple channels in a patient with antiphospholipid syndrome: The optical coherence tomography findings. Intern Med. 2017;56(11):1351-1356.
- Jang IK, Tearney GJ, MacNeill B, et al. In vivo characterization of coronary atherosclerotic plaque by use of optical coherence tomography. Circulation. 2005;111(12):1551-1555.
- Jia H, Abtahian F, Aguirre AD, et al. In vivo diagnosis of plaque erosion and calcified nodule in patients with acute coronary syndrome by intravascular optical coherence tomography. J Am Coll Cardiol. 2013;62(19):1748-1758.
- Jia H, Kubo T, Akasaka T, Yu B. Optical coherence tomography guidance in management of acute coronary syndrome caused by plaque erosion. Circ J. 2018;82(2):302-308.
- Jiang Y, He LP, Gong R, et al. Comparison of clinical outcomes between intravascular optical coherence tomography-guided and angiography-guided stent implantation: A meta-analysis of randomized control trials and systematic review. Medicine (Baltimore). 2019;98(6):e14300.
- Jones MR, Attizzani GF, Given CA 2nd, et al. Intravascular frequency-domain optical coherence tomography assessment of carotid artery disease in symptomatic and asymptomatic patients. JACC Cardiovasc Interv. 2014;7(6):674-684.
- Jorge E, Baptista R, Calisto J, et al. Optical coherence tomography of the pulmonary arteries: A systematic review. J Cardiol. 2016;67(1):6-14.
- Jung T-M, Nairuz T, Kim C-H, Lee J-H. Development of a brain catheter for optical coherence tomography in advanced cerebrovascular diagnostics. Biosensors (Basel). 2025;15(3):170.
- Karimi Galougahi K, Dakroub A, Chau K, et al. Utility of optical coherence tomography in acute coronary syndromes. Catheter Cardiovasc Interv. 2023;102(1):46-55.
- Karamasis GV, Varlamos C, Benetou D-R, et al. The usefulness of intracoronary imaging in patients with ST-segment elevation myocardial infarction. J Clin Med. 2023;12(18):5892.
- Kawamori H, Shite J, Shinke T, et al. The ability of optical coherence tomography to monitor percutaneous coronary intervention: Detailed comparison with intravascular ultrasound. J Invasive Cardiol. 2010;22(11):541-545.
- Kim H, Ahn J-M, Kang D-Y, et al. Management of coronary vulnerable plaque with medical therapy or local preventive percutaneous coronary intervention. JACC Asia. 2024;4(6):425-443.
- Kimura S, Sugiyama T, Hishikari K, et al. Association of intravascular ultrasound- and optical coherence tomography-assessed coronary plaque morphology with periprocedural myocardial injury in patients with stable angina pectoris. Circ J. 2015;79(9):1944-1953.
- Kovacic JC, Reynolds HR, Alasnag M, et al. Acute coronary syndromes in premenopausal women: A scientific statement from the American Heart Association. Circulation. 2026;153(7):e89-e108.
- Kubo T, Akasaka T. Recent advances in intracoronary imaging techniques: Focus on optical coherence tomography. Expert Rev Med Devices. 2008;5(6):691-697.
- Kubo T, Matsuo Y, Ino Y, et al. Optical coherence tomography analysis of attenuated plaques detected by intravascular ultrasound in patients with acute coronary syndromes. Cardiol Res Pract. 2011;2011:687515.
- Lee JM, Choi KH, Koo B-K, et al. Intravascular ultrasound or optical coherence tomography-defined anatomic severity and hemodynamic severity assessed by coronary physiologic indices. Rev Esp Cardiol (Engl Ed). 2020;73(10):812-821.
- Lee MS, Shlofmitz E, Kong J, et al. Impact of the use of intravascular imaging on patients who underwent orbital atherectomy. J Invasive Cardiol. 2018;30(2):77-80.
- Lee SY, Hong MK. Stent evaluation with optical coherence tomography. Yonsei Med J. 2013;54(5):1075-1083.
- Levine GN, Bates ER, Blankenship JC, et al. 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention. A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Society for Cardiovascular Angiography and Interventions. J Am Coll Cardiol. 2011;58(24):e44-e122.
- Manfrini O, Slucca M, Bugiardini R. Optical coherence tomography. G Ital Cardiol (Rome). 2007;8(1):28-33.
- Mansourian E, Pavlin-Premrl D, Friedman J, et al. High-frequency optical coherence tomography for endovascular management of cerebral aneurysms. J Med Imaging Radiat Oncol. 2024;68(4):447-456.
- McGovern E, Hosking MCK, Balbacid E, et al. Optical coherence tomography for the early detection of coronary vascular changes in children and adolescents after cardiac transplantation: Findings from the International Pediatric OCT registry. JACC Cardiovasc Imaging. 2019;12(12):2492-2501.
- Miyamoto Y, Okura H, Kume T, et al. Plaque characteristics of thin-cap fibroatheroma evaluated by OCT and IVUS. JACC Cardiovasc Imaging. 2011;4(6):638-646.
- Niu Y, Bai N, Ma Y, et al. Efficacy of intravascular imaging-guided drug-eluting stent implantation: A systematic review and meta-analysis of randomized clinical trials. BMC Cardiovasc Disord. 2022;22(1):327.
- Nogic J, Prosser H, O'Brien J, et al. The assessment of intermediate coronary lesions using intracoronary imaging. Cardiovasc Diagn Ther. 2020;10(5):1445-1460.
- Prati F, Regar E, Mintz GS, et al; Expert's OCT Review Document. Expert review document on methodology, terminology, and clinical applications of optical coherence tomography: Physical principles, methodology of image acquisition, and clinical application for assessment of coronary arteries and atherosclerosis. Eur Heart J. 2010;31(4):401-415.
- Raffel OC, Merchant FM, Tearney GJ, et al. In vivo association between positive coronary artery remodelling and coronary plaque characteristics assessed by intravascular optical coherence tomography. Eur Heart J. 2008;29(14):1721-1728.
- Rao SV, O'Donoghue ML, Ruel M, et al. 2025 ACC/AHA/ACEP/NAEMSP/SCAI guideline for the management of patients with acute coronary syndromes: A report of the American College of Cardiology/American Heart Association Joint Committee on clinical practice guidelines. Circulation. 2025;151(13):e771-e862.
- Regar E, Weissman NJ, Muhlestein JB. Intravascular ultrasound, optical coherence tomography, and angioscopy of coronary circulation. UpToDate [online serial]. Waltham, MA: UpToDate; 2011.
- Rico-Jimenez JJ, Campos-Delgado DU, Villiger M, et al. Automatic classification of atherosclerotic plaques imaged with intravascular OCT. Biomed Opt Express. 2016;7(10):4069-4085.
- Roleder T, Jakała J, Kałuza GL, et al. The basics of intravascular optical coherence tomography. Postepy Kardiol Interwencyjnej. 2015;11(2):74-83.
- Roleder T, Skowerski M, Wiecek A, et al. Long-term follow-up of renal arteries after radio-frequency catheter-based denervation using optical coherence tomography and angiography. Int J Cardiovasc Imaging. 2016;32(6):855-862.
- Schwaiger JP, Loder CD, Dobarro D, et al. Optical coherence tomography evaluation of pulmonary arterial vasculopathy in systemic sclerosis. Sci Rep. 2017;7:43304.
- Siddiqi TJ, Khan MS, Galougahi KK. Optical coherence tomography versus angiography and intravascular ultrasound to guide coronary stent implantation: A systematic review and meta-analysis. Catheter Cardiovasc Interv. 2022;100 Suppl 1:S44-S56.
- Smilowitz NR, Mohananey D, Razzouk L, et al. Impact and trends of intravascular imaging in diagnostic coronary angiography and percutaneous coronary intervention in inpatients in the United States. Catheter Cardiovasc Interv. 2018;92(6):E410-E415.
- Stamper D, Weissman NJ, Brezinski M. Plaque characterization with optical coherence tomography. J Am Coll Cardiol. 2006;47(8 Suppl):C69-C79.
- Sun L, Jiang Q, Xie Y, et al. Optical coherence tomography of the pulmonary arteries in children with congenital heart diseases: A systematic review. Pediatr Investig. 2022;6(4):264-270.
- Tang T, Zhou J, Thomas AM, et al. A systematic review of application of frequency-domain optical coherence tomography in cerebral large artery atherosclerosis. Neuroradiology. 2025;67(5):1139-1151.
- Thompson BT, Kabrhel C, Pena C. Clinical presentation, evaluation, and diagnosis of the nonpregnant adult with suspected acute pulmonary embolism. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2018.
- Tsimikas S, DeMaria AN. The clinical emergence of optical coherence tomography: Defining a role in intravascular imaging. J Am Coll Cardiol. 2012;59(12):1090-1091.
- Uemura S, Ishigami K, Soeda T, et al. Thin-cap fibroatheroma and microchannel findings in optical coherence tomography correlate with subsequent progression of coronary atheromatous plaques. Eur Heart J. 2012;33(1):78-85.
- Ughi GJ, Van Dyck CJ, Adriaenssens T, et al. Automatic assessment of stent neointimal coverage by intravascular optical coherence tomography. Eur Heart J Cardiovasc Imaging. 2014;15(2):195-200.
- Wang B, Tao K, Hu X, et al. Intravascular optical coherence tomography utilizing a miniature piezoelectric-driven probe. IEEE Trans Biomed Eng. 2023;70(12):3490-3500.
- Wolfrum M, De Maria GL, Banning AP. Optical coherence tomography to guide percutaneous treatment of coronary bifurcation disease. Expert Rev Cardiovasc Ther. 2017;15(9):705-713.
- Xie Z, Tian J, Ma L, et al. Comparison of optical coherence tomography and intravascular ultrasound for evaluation of coronary lipid-rich atherosclerotic plaque progression and regression. Eur Heart J Cardiovasc Imaging. 2015;16(12):1374-1380.
- Yamaguchi T, Terashima M, Akasaka T, et al. Safety and feasibility of an intravascular optical coherence tomography image wire system in the clinical setting. Am J Cardiol. 2008;101(5):562-567.
- Yonetsu T, Bouma BE, Kato K, et al. Optical coherence tomography -- 15 years in cardiology. Circ J. 2013;77(8):1933-1940.
- Yonetsu T, Wakabayashi K, Mizukami T, et al; ATLAS-OCT Investigators. Optical coherence tomography-guided percutaneous coronary intervention for ST-segment elevation myocardial infarction: Rationale and design of the ATLAS-OCT Study. Am J Cardiol. 2023;203:466-472.
- Zafar H, Sharif F, Leahy MJ. Feasibility of intracoronary frequency domain optical coherence tomography derived fractional flow reserve for the assessment of coronary artery stenosis. Int Heart J. 2014;55(4):307-311.
