Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) of the Spine
Number: 0236
Table Of Contents
PolicyApplicable CPT / HCPCS / ICD-10 Codes
Background
References
Policy
Scope of Policy
This Clinical Policy Bulletin addresses magnetic resonance imaging (MRI) and computed tomography (CT) of the spine.
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Medical Necessity
Aetna considers magnetic resonance imaging (MRI) and computed tomography (CT) of the spine medically necessary when any of the following criteria is met:
- Clinical evidence of spinal stenosis; or
- Clinical suspicion of a spinal cord or cauda equina compression syndrome; or
- Congenital anomalies or deformities of the spine; or
- Diagnosis and evaluation of lumbar epidural lipomatosis; or
- Evaluation of recurrent symptoms after spinal surgery; or
- Evaluation prior to epidural injection to rule out tumor or infection and to delineate the optimal anatomical location for performing the injection; or
- Follow-up of evaluation for spinal malignancy or spinal infection; or
- Known or suspected myelopathy (e.g., multiple sclerosis) for initial diagnosis when MRI of the brain is negative or symptoms mimic those of other spinal or brainstem lesions; or
- Known or suspected primary spinal cord tumors (malignant or non-malignant); or
- Persistent back or neck pain with radiculopathy as evidenced by pain plus objective findings of motor or reflex changes in the specific nerve root distribution, and no improvement after 6 weeks of conservative therapyFootnotes for conservative therapy*; or
- Primary spinal bone tumors or suspected vertebral, paraspinal, or intraspinal metastases; or
- Progressively severe symptoms despite conservative management; or
- Rapidly progressing neurological deficit, or major motor weakness; or
- Severe back pain (e.g., requiring hospitalization); or
- Spondylolisthesis and degenerative disease of the spine that has not responded to 4 weeks of conservative therapyFootnotes for conservative therapy*; or
- Suspected infectious process (e.g., osteomyelitis epidural abscess of the spine or soft tissue); or
- Suspected spinal cord injury secondary to trauma; or
- Suspected spinal fracture and/or dislocation secondary to trauma (if plain films are not conclusive); or
- Suspected transverse myelitis.
Footnotes for conservative therapy* Conservative therapy = moderate activity, analgesics, non-steroidal anti-inflammatory drugs, muscle relaxants.
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Experimental, Investigational, or Unproven
- Aetna considers MRI and CT of the spine experimental, investigational, or unproven for all other indications because their clinical value for indications other than the ones listed above has not been established. Clinical guidelines, including those from the Agency for Healthcare Policy and Research, have consistently recommended against routine imaging studies for acute low back pain.
- Aetna considers the use of MRI for further evaluation of unstable injury in neurologically intact individuals with blunt trauma after a negative cervical spine CT result not medically necessary.
- Aetna considers dynamic-kinetic MRI experimental, investigational, or unproven for evaluation of the cervical spine because its effectiveness has not been established.
- Aetna considers the use of routine MRI after a normal CT of the cervical spine in obtunded or comatose individuals experimental, investigational, or unproven because the clinical value of this approach has not been established.
- Aetna considers dual-energy CT experimental, investigational, or unrpoven for the evaluation of bone marrow edema and fracture lines in acute vertebral fractures because the clinical value of this approach has not been established.
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Related Policies
Background
Because of its complexity, the spine is probably the most difficult part of the skeletal system to evaluate radiologically. Improvement of computed tomography (CT) scanners and the advent of magnetic resonance imaging (MRI) have changed the approach to diagnostic imaging of the spine. Previously, invasive modalities were required to obtain information that is now available with non-invasive technologies.
The appropriate use of these new technologies is still somewhat unsettled. The focus is on which test will provide the most accurate and cost effective diagnostic information for each particular clinical situation. Computed tomographic scan, CT myelography, MRI and plain radiography all have their place in the diagnostic work-up of problems related to the spine.
Bulging intervertebral discs have been found in over half of all otherwise asymptomatic adults. It is therefore, important to perform MRI or CT at the right time and to interpret the results in the context of the clinical findings to ensure an accurate diagnosis and avoid unnecessary treatment of conditions that may not be the cause of a patient's symptoms.
According to accepted guidelines, MRI is the preferred method of imaging for each of the medically necessary indications listed in the Policy section, with the exception of
- suspected spinal fracture or dislocation due to trauma, where CT scan is the preferred method of imaging if plain films are inconclusive, and
- evaluation of a patient with signs or symptoms of spinal stenosis, where MRI or CT are equally appropriate. For evaluation of recurrent symptoms after spinal surgery, MRI with and without gadolinium enhancement, is the preferred method of imaging.
Magnetic resonance imaging or CT evaluation of chronic mechanical low back pain (LBP) without radiculopathy or neurologic deficit, trauma, or clinical suspicion of systemic disorder (e.g., infectious process, metastatic disease) is not necessary unless back pain is severe (e.g., requiring hospitalization) or where symptoms are progressing despite conservative management (ICSI, 2002).
The American College of Physicians (2012) has recommended against obtaining imaging studies in patients with non-specific low back pain. In patients with back pain that cannot be attributed to a specific disease or spinal abnormality following a history and physical examination (e.g., non-specific low back pain), imaging with plain radiography, computed tomography (CT) scan, or magnetic resonance imaging (MRI) does not improve patient outcomes. The American Academy of Family Physicians (2012) recommends against do imaging for low back pain within the first six weeks, unless red flags are present. Red flags include, but are not limited to, severe or progressive neurological deficits or when serious underlying conditions such as osteomyelitis are suspected. Imaging of the lower spine before six weeks does not improve outcomes, but does increase costs. Low back pain is the fifth most common reason for all physician visits. The North American Spine Society (2013) has issued similar recommendations.
Cho et al (2009) reported the results of a systematic review and meta-analysis of imaging strategies for LBP without indications of serious underlying conditions. Inclusion criteria were randomized controlled trials that compared immediate, routine lumbar imaging (or routine provision of imaging findings) versus usual clinical care without immediate lumbar imaging (or not routinely providing results of imaging) for LBP without indications of serious underlying conditions. Primary outcomes were improvement in pain or function. Secondary outcomes were improvement in mental health, quality of life, patient satisfaction, and overall improvement. Outcomes were categorized as short-term (less than or equal to 3 months), long-term (greater than 6 months to less than or equal to 1 year), or extended (greater than 1 year). A total of 6 trials met the inclusion criteria: 4 assessed lumbar radiography and 2 assessed MRI or CT. Duration of follow-up ranged from 3 weeks to 2 years. One trial excluded patients with sciatica or other symptoms of radiculopathy, and 1 did not report the proportion of patients with such symptoms. In the other 4 trials, the proportion of patients with sciatica or radiculopathy ranged from 24 % to 44 %. Three trials compared immediate lumbar radiography with usual clinical care without immediate lumbar radiography, and 1 compared immediate lumbar radiography with a brief education intervention plus lumbar radiography, if no improvement was seen by 3 weeks. Patients (n = 1,804) enrolled in these trials had mainly acute or subacute (less than 12 weeks) LBP, and all trials were done in primary-care or urgent-care settings. Two studies assessed advanced imaging modalities. One study compared immediate MRI or CT with usual clinical care without advanced imaging in patients with mainly chronic LBP (82 % had LBP for greater than 3 months) referred to a surgeon, whereas in the other study all patients with LBP for less than 3 weeks underwent MRI, with randomization to routine notification of results within 48 hours versus notification of results only if clinically indicated. Patients were recruited from various settings (primary care, spine clinic, or emergency room). In both trials, the proportion of patients who underwent lumbar radiography before enrollment was not reported. The most frequent methodological shortcoming was lack of (or unclear use of) blinded outcome assessment (5 of 6 trials), followed by inadequate description of randomization method (4 of 6 trials). All trials excluded patients with features suggestive of a serious underlying condition, but exclusion criteria varied and trials did not indicate the number of patients excluded because of such factors. The authors found no significant difference between routine, immediate lumbar imaging and usual clinical care without immediate imaging for improvement in pain or function at short-term or long-term follow-up. In the trial that reported extended (2-year) follow-up data, immediate MRI or CT was not better than usual clinical care without immediate imaging on either the EuroQol-5D (mean difference 0.02, 95 % confidence interval: -0.02 to 0.07, 0 to 1 scale) or the SF-36 mental health score (-1.50, -4.09 to 1.09, 0 to 100 scale) in unadjusted analyses. The authors concluded that lumbar imaging forLBP without indications of serious underlying conditions does not improve clinical outcomes and that clinicians should refrain from routine, immediate lumbar imaging in patients with acute or subacute LBP and without features suggesting a serious underlying condition.
In a meta-analysis, Schoenfeld et al (2010) examined if adding an MRI would provide useful information that alters treatment when a CT scan reveals no evidence of injury in obtunded blunt trauma patients. Published studies from 2000 to 2008 involving patients undergoing MRI for the purposes of further cervical spine evaluation after a "negative" CT scan were identified via a literature search of online databases. Data from eligible studies were pooled and original scale meta-analyses were performed to calculate overall sensitivity, specificity, positive and negative predictive values, likelihood ratios, and relative risk. The Q-statistic p value was used to evaluate heterogeneity. A total of 11 studies met the inclusion criteria, yielding data on 1,550 patients with a negative CT scan after blunt trauma subsequently evaluated with a MRI. The MRI detected abnormalities in 182 patients (12 %). Ninety traumatic injuries were identified, including ligamentous injuries (86/182), fractures and dislocations (4/182). In 96 cases (6 % of the cohort), the MRI identified an injury that altered management. Eighty-four patients (5 %) required continued collar immobilization and 12 (1 %) required surgical stabilization. The Q-statistic p value for heterogeneity was 0.99, indicating the absence of heterogeneity among the individual study populations. The authors concluded that reliance on CT imaging alone to "clear the cervical spine" after blunt trauma can lead to missed injuries. The findings of this study supported the addition of MRI in evaluating patients who are obtunded, or unexaminable, despite a negative CT scan.
Callaghan et al (2012) examined diagnostic practice patterns as an early step in identifying opportunities to improve efficiency of care of patients with peripheral neuropathy. The 1996 to 2007 Health and Retirement Study Medicare claims-linked database was used to identify individuals with an incident diagnosis of peripheral neuropathy using International Classification of Diseases, Ninth Revision, codes and required no previous neuropathy diagnosis during the preceding 30 months. Focusing on 15 relevant tests, these investigators examined the number and patterns of tests and specific test utilization 6 months before and after the incident neuropathy diagnosis. Medicare expenditures were assessed during the baseline, diagnostic, and follow-up periods. Of the 12,673 patients, 1,031 (8.1 %) received a new International Classification of Diseases, Ninth Revision, diagnosis of neuropathy and met the study inclusion criteria. Of the 15 tests considered, a median of 4 (interquartile range, 2 to 5) tests were performed, with more than 400 patterns of testing. Magnetic resonance imaging of the brain or spine was ordered in 23.2 % of patients, whereas a glucose tolerance test was rarely obtained (1.0 %). Mean Medicare expenditures were significantly higher in the diagnostic period than in the baseline period ($14,362 versus $8,067, p < 0.001). The authors concluded that patients diagnosed as having peripheral neuropathy typically undergo many tests, but testing patterns are highly variable. Almost 25 % of patients receiving neuropathy diagnoses undergo high-cost, low-yield MRI, whereas few receive low-cost, high-yield glucose tolerance tests. Expenditures increase substantially in the diagnostic period. The authors stated that more research is needed to define effective and efficient strategies for the diagnostic evaluation of peripheral neuropathy.
Also, an UpToDate review on "Overview of polyneuropathy" (Rutkove, 2012) does not mention the use of MRI or CT in the diagnostic evaluation of individuals with polyneuropathy.
The Institute for Clinical Systems Improvement clinical practice guideline on "Adult acute and subacute low back pain" (ICSI, 2012) stated that imaging (CT, MRI, or x-ray) is not recommended for non-specific low-back pain [strong recommendation, moderate quality evidence].
El Barzouhi et al (2013) noted that MRI is frequently performed during follow-up in patients with known lumbar-disk herniation and persistent symptoms of sciatica. The association between findings on MRI and clinical outcome is controversial. These investigators studied 283 patients in a randomized trial comparing surgery and prolonged conservative care for sciatica and lumbar-disk herniation. Patients underwent MRI at baseline and after 1 year. These researchers used a 4-point scale to assess disk herniation on MRI, ranging from 1 for "definitely present" to 4 for "definitely absent". A favorable clinical outcome was defined as complete or nearly complete disappearance of symptoms at 1 year. These investigators compared proportions of patients with a favorable outcome among those with a definite absence of disk herniation and those with a definite, probable, or possible presence of disk herniation at 1 year. The area under the receiver-operating-characteristic (ROC) curve was used to assess the prognostic accuracy of the 4-point scores regarding a favorable or unfavorable outcome, with 1 indicating "perfect discriminatory value" and 0.5 or less indicating "no discriminatory value". At 1 year, 84 % of the patients reported having a favorable outcome. Disk herniation was visible in 35 % with a favorable outcome and in 33 % with an unfavorable outcome (p = 0.70). A favorable outcome was reported in 85 % of patients with disk herniation and 83 % without disk herniation (p = 0.70). Assessment of disk herniation by means of MRI did not distinguish between patients with a favorable outcome and those with an unfavorable outcome (area under ROC curve, 0.48). The authors concluded that MRI performed at 1-year follow-up in patients who had been treated for sciatica and lumbar-disk herniation did not distinguish between those with a favorable outcome and those with an unfavorable outcome. Moreover, they stated that further research is needed to evaluate the value of MRI in clinical decision-making for patients with persistent or recurrent sciatica.
Steffens et al (2014) systematically reviewed whether MRI findings of the lumbar spine predict future LBP in different samples with and without LBP. MEDLINE, CINAHL and EMBASE databases were searched. Included were prospective cohort studies investigating the relationship between baseline MRI abnormalities of the lumbar spine and clinically important LBP outcome at follow-up. These researchers excluded cohorts with specific diseases as the cause of their LBP. Associations between MRI findings and LBP pain outcomes were extracted from eligible studies. A total of 12 studies met the inclusion criteria; 6 studies presented data on participants with current LBP; 1 included a sample with no current LBP, 3 included a sample with no history of LBP and 2 included mixed samples. Due to small sample size, poor overall quality and the heterogeneity between studies in terms of participants, MRI findings and clinical outcomes investigated, it was not possible to pool findings. No consistent associations between MRI findings and outcomes were identified. Single studies reported significant associations for Modic changes type 1 with pain, disc degeneration with disability in samples with current LBP and disc herniation with pain in a mixed sample. The authors concluded that the limited number, heterogeneity and overall quality of the studies do not permit definite conclusions on the association of MRI findings of the lumbar spine with future LBP
Weber et al (2015) evaluated the incremental diagnostic value of spine MRI evaluated separately from and combined with sacroiliac joint (SIJ) MRI in non-radiographic axial spondyloarthritis (nr-axSpA) compared with SIJ MRI alone. The study sample comprised 2 independent cohorts A/B of 130 consecutive patients aged less than or equal to 50 years with back pain, newly referred to 2 university clinics, and 20 healthy controls. Patients were classified according to clinical examination and pelvic radiographs as having nr-axSpA (n = 50), ankylosing spondylitis (n = 33), or non-specific back pain (n = 47). Four readers assessed SIJ and spine MRI separately 6 months apart, and 1 to 12 months later both scans simultaneously using standardized modules. Readers recorded presence/absence of SpA and their level of confidence in this conclusion on a 0 to 10 scale (0 = definitely not; 10 = definite). These researchers analyzed differences between SIJ MRI versus spine MRI alone, and SIJ MRI alone versus combined MRI, descriptively by the number/percentage of subjects according to the mean of 4 readers. In cohorts A/B, 15.8 %/24.2 % of patients with nr-axSpA having a negative SIJ MRI were re-classified as being positive for SpA by global evaluation of combined scans. However, 26.8 %/11.4 % of non-specific back pain controls and 17.5 % of healthy volunteers with a negative SIJ MRI were falsely re-classified as having SpA by combined MRI. Low confidence in a diagnosis of SpA by SIJ MRI increased to high confidence by combined MRI in 6.6 %/7.3 % of patients with nr-axSpA. The authors concluded that combined spine and SIJ MRI added little incremental value compared with SIJ MRI alone for diagnosing patients with nr-axSpA and enhancing confidence in this diagnosis.
On behalf of the Tufts Medical Center Evidence-based Practice Center, Dahabreh and colleagues (2011) performed a systematic review of emerging MRI technologies for musculoskeletal imaging under loading stress for the Agency for Healthcare Research and Quality (AHRQ). The review included 57 studies about MRI under physiologic loading stress performed in an upright or sitting position or under axial loading by using a compression device. The most commonly imaged regions were the spine (33 studies) and knee (13 studies). Most studies had a cross-sectional (n = 37) or case-control (n = 13) design and reported on anatomical measurements rather than patient-relevant end points. Studies were generally small: The median (25th, 75th percentile) number of case patients was 26 (17, 45), and the median (25th, 75th percentile) number of control participants was 13 (12, 20 for case-control studies). Fifteen of 57 studies used at least 2 imaging tests and reported on diagnostic or patient-relevant outcomes, but did not report meaningful information on the relative performance of the tests. In 10 studies that included information on adverse effects, 5 % to 15 % of participants reported new-onset or worsening pain and neuropathy during MRI under loading stress. The authors concluded that available evidence is insufficient to support the clinical utility of MRI under loading stress for musculoskeletal conditions.
Lord et al (2014) reviewed the body of literature related to kinetic MRI (kMRI) of the cervical spine. A review of literature related to kMRI was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. These researchers included 16 prospective and retrospective studies of symptomatic and asymptomatic patients who underwent kMRI of the cervical spine. The authors concluded that data suggested that kMRI is able to provide meaningful information regarding changes in the cervical spine in both normal and pathologic segments. Moreover, they stated that a prospective study comparing MRI and kMRI is needed to confirm clinically utility of this technology.
Also, an UpToDate review on "Evaluation of the patient with neck pain and cervical spine disorders" (Isaac and Anderson, 2014) states that "Magnetic resonance imaging (MRI) should be the first-line imaging study performed in patients with progressive signs or symptoms of neurologic disease. MRI should also be obtained if there is a suspicion for infection or malignancy and if there are moderate to severe neck symptoms beyond six weeks, even if plain films are negative …. A non-contrast MRI is sufficient in the majority of cases. The addition of gadolinium contrast intravenously allows better diagnosis of infection, tumor, or post-surgical epidural fibrosis, and can be ordered subsequently if the non-contrast study is inconclusive". It does not mention the use of dynamic-kinetic MRI.
In a systematic review, Suri and colleagues (2015) examined if lumbar muscle characteristics on MRI or CT can inform clinicians as to the course of future LBP, functional limitations, or physical performance, in adults with or without LBP. These investigators searched PubMed, Embase, and CINAHL through October 2014 for articles published in English in which authors assessed lumbar muscle characteristics on conventional MRI/CT as predictors of future LBP, functional limitations, or physical performance in adults. Studies with only post-surgical subjects were excluded. The search identified 3,554 articles, of which 6 observational cohort studies were included in the final review. These researchers used the Newcastle Ottawa Scale to evaluate potential bias. Data were extracted on study design, study population, sample size, participant characteristics, details of MRI/CT assessments, interventions, study outcomes, analysis methods, and study results. Because of heterogeneity between studies, these researchers conducted a qualitative evidence synthesis. Among high-quality studies, there was limited evidence that, for individuals with or without LBP, greater MRI-detected multifidus cross-sectional area at L5 to S1 predicted greater LBP intensity at 1-year follow-up, lesser erector spinae fat infiltration (FI) at L5 to S1 predicted greater LBP intensity at 15-year follow-up, and greater erector spinae side-to-side FI asymmetry at L3 to L4 predicted lower LBP frequency at 15-year follow-up; however, there was also limited evidence that all other MRI-detected para-spinal muscle characteristics examined were not predictive of LBP incidence, prevalence, frequency, or intensity at follow-up durations ranging from 1 to 15 years. There was limited evidence that greater CT-detected trunk muscle FI predicted worse physical performance in older adults at 3-year follow-up, but that trunk muscle cross-sectional area did not. The authors concluded that few lumbar muscle characteristics have limited evidence for an association with future LBP and physical performance outcomes, and the vast majority have limited evidence for having no association with such outcomes.
Routine MRI after a Normal CT of the Cervical Spine in Obtunded or Comatose Individuals
Khanna and associates (2012) stated that the value of MRI in the evaluation of the obtunded or comatose patient with a potential neck injury is a controversial subject. Some authors have suggested that MRI of the cervical spine adds no value in the evaluation of patients with a normal CT of the neck. However, others have suggested that MRI is the gold standard for clearing the cervical spine in a clinically suspicious or unevaluable blunt trauma patient. These researchers examined their data in regard to these conflicting hypotheses. Five consecutive years of data from 17,000 patients seen at the authors’ Level I trauma center yielded 512 individuals who underwent both CT and MRI of the cervical spine. Of the latter group, 150 individuals met 3 strict inclusion criteria for this study:
- obtundation (Glasgow Coma Scale less than or equal to 13, with 94 of this group comatose [Glasgow Coma Scale less than or equal to 8]);
- no obvious neurologic deficits; and
- a normal cervical CT.
The effect of MRI on the clinical management of these patients was evaluated. Among the 150 obtunded or comatose patients with a negative CT, the majority (51 %) had a normal MRI. Among the patients with a positive MRI, the most common MRI-positive findings were ligamentous and soft tissue injury (81 %). However, no MRI findings were deemed unstable, and no surgical intervention or change in the clinical management aside from collar immobilization of these individuals occurred after MRI. The authors concluded that the addition of a cervical MRI to the evaluation protocol of obtunded or comatose patients with an otherwise normal neurologic examination and a normal cervical CT did not provide any additional useful information to change the management of these patients.
Raza and co-workers (2013) stated that a true gold standard to rule out a significant cervical spine injury in subset of blunt trauma patients with altered sensorium is still to be agreed upon. These investigators examined if in obtunded adult patients with blunt trauma, a clinically significant injury to the cervical spine be ruled out on the basis of a normal multi-detector cervical spine CT. Comprehensive database search was conducted to include all the prospective and retrospective studies on blunt trauma patients with altered sensorium undergoing cervical spine multi-detector CT scan as core imaging modality to "clear" the cervical spine. The studies used 2 main gold standards, MRI of the cervical spine and/or prolonged clinical follow-up. The data was extracted to report true positive, true negatives, false positives and false negatives. Meta-analysis of sensitivity, specificity, negative and positive predictive values (NPV and PPV) was performed using Meta Analyst Beta 3.13 software. These researchers also performed a retrospective investigation comparing a robust clinical follow-up and/or cervical spine MRI findings in 53 obtunded blunt trauma patients, who previously had undergone a normal multi-detector CT scan of the cervical spine reported by a radiologist. A total of 10 studies involving 1,850 obtunded blunt trauma patients with initial cervical spine CT scan reported as normal were included in the final meta-analysis. The cumulative NPV and specificity of cervical spine CT of the 10 studies was 99.7 % (95 % confidence interval [CI]: 99.4 to 99.9 %). The PPV and sensitivity was 93.7 % (95 % CI: 84.0 to 97.7 %). In the retrospective review of obtunded blunt trauma patients, none was later diagnosed to have significant cervical spine injury that required a change in clinical management. The authors concluded that in a blunt trauma patient with altered sensorium, a normal cervical spine CT scan was conclusive to safely rule out a clinically significant cervical spine injury. They stated that the findings of this meta-analysis strongly supported the removal of cervical precautions in obtunded blunt trauma patient after normal cervical spine CT; any further imaging like MRI of the cervical spine should be performed on case-to-case basis.
Smith (2014) addressed the question "Can CT alone provide adequate clinical information to clear the cervical spine in the obtunded patient"? The author performed a search of the literature for studies that compared CT with other radiologic modalities utilized to clear the cervical spine in obtunded patients. PubMed, TRIP database, SUMSearch, Cochrane library, and Google Scholar were the databases applied. Additional sources included bibliographies of selected articles. Studies that integrated CT scan with at least 1 other diagnostic examination were included. A review of 11 studies and 1 meta-analysis encompassing 2,458 and 14,327 patients, respectively, met inclusion criteria. The meta-analysis generated a NPV for CT scan of 100 % without evidence of acute injury with an overall sensitivity and specificity of 99.9 % each. The author concluded that these findings suggested that CT alone is a reliable clinical indicator to clear the cervical spine in obtunded patients.
Patel and associated (2015) noted that with the use of the framework advocated by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group, they performed a systematic review and to develop evidence-based recommendations that may be used to answer the following PICO [Population, Intervention, Comparator, Outcomes] question: In the obtunded adult blunt trauma patient, should cervical collar removal be performed after a negative high-quality cervical spine (C-spine) CT result alone or after a negative high-quality C-spine CT result combined with adjunct imaging, to reduce peri-clearance events, such as new neurologic change, unstable C-spine injury, stable C-spine injury, need for post-clearance imaging, false-negative CT imaging result on re-review, pressure ulcers, and time to cervical collar clearance? The protocol was registered with the PROSPERO international prospective register of systematic reviews on August 23, 2013. Eligibility criteria consisted of adult blunt trauma patients 16 years or older, who underwent C-spine CT with axial thickness of less than 3 mm and who were obtunded using any definition. Quantitative synthesis via meta-analysis was not possible because of pre-post, partial-cohort, quasi-experimental study design limitations and the consequential incomplete diagnostic accuracy data. Of 5 articles with a total follow-up of 1,017 included subjects, none reported new neurologic changes (paraplegia or quadriplegia) after cervical collar removal. There was a worst-case 9 % (161 of 1,718 subjects in 11 studies) cumulative literature incidence of stable injuries and a 91 % NPV of no injury, after coupling a negative high-quality C-spine CT result with 1.5-T MRI, upright x-rays, flexion-extension CT, and/or clinical follow-up. Similarly, there was a best-case 0 % (0 of 1,718 subjects in 11 studies) cumulative literature incidence of unstable injuries after negative initial imaging result with a high-quality C-spine CT. The authors concluded that in obtunded adult blunt trauma patients, they conditionally recommended cervical collar removal after a negative high-quality C-spine CT scan result alone.
Plackett and colleagues (2016) noted that the role of cervical spine MRI in the evaluation of clinically unevaluable blunt trauma patients has been called into question by several recent studies. These investigators performed a PubMed search for all studies comparing CT and MRI in the assessment of the cervical spine in patients who cannot be evaluated clinically. The radiologic findings and clinical outcomes from each study were collated for analysis. Data for 1,714 patients were available. All patients had a negative CT scan and then underwent an MRI. There were 271 (15.8 %) patients who had a previously undocumented finding on MRI with the majority (98.2 %) being a ligamentous injury. Only 5 injuries (1.8 %) resulted in surgical intervention. The authors concluded that MRI identified additional injuries; however, the vast majority were of minor clinical significance. They stated that routine MRI after a negative CT of the cervical spine is not supported by the current literature.
Endler and colleagues (2021) noted that cervical spine CT is regularly carried out to exclude cervical spine injury during the initial evaluation of trauma patients. Patients with asymmetry of the lateral atlanto-dental interval (LADI) often undergo subsequent MRI to rule out ligamentous injuries. The clinical relevance of an asymmetric LADI and the benefit of additional MRI remain unclear. In a retrospective study, these researchers examined the diagnostic benefit of additional MRI in patients with blunt trauma who have asymmetry of the LADI and no other cervical injuries. Patients who underwent cervical spine CT during initial trauma evaluation between March 2017 and August 2019 were examined. Those who underwent subsequent MRI because of LADI asymmetry of 1 mm or greater with no other signs of cervical injury were identified and re-evaluated by 2 readers blinded to clinical data and initial study reports regarding possible ligamentous injuries. Among 1,553 patients, 146 (9 %) had LADI asymmetry of 1 mm or greater. Of these, 46 patients (mean age ± standard deviation, 39 years ± 22; 28 men; median LADI asymmetry, 2.4 mm [inter-quartile range (IQR), 1.8 to 3.1 mm]) underwent supplementary MRI with no other signs of cervical injury at initial CT; 10 of the 46 patients (22 %) showed cervical tenderness at clinical examination, and 36 patients (78 %) were asymptomatic. In 2 of the 46 patients (4 %), MRI revealed alar ligament injury; both of these patients showed LADI asymmetry greater than 3 mm, along with cervical tenderness at clinical examination, and underwent treatment for ligamentous injury. In 13 of the 46 patients (28 %), signal intensity alterations of alar ligaments without signs of rupture were observed; 4 of these 13 patients (31 %) were subsequently treated for ligamentous injury despite being asymptomatic. The authors concluded that subsequent MRI following CT of the cervical spine in trauma patients with LADI asymmetry may have diagnostic benefit only in symptomatic patients. In asymptomatic patients without proven cervical injuries, subsequent MRI showed no diagnostic benefit and may even lead to over-treatment.
Dynamic Supine Magnetic Resonance Imaging
Xu and colleagues (2017) analyzed the current evidence regarding the role of dynamic supine MRI (dsMRI) in the evaluation of cervical spondylotic myelopathy. A total of 13 studies were identified through a comprehensive literature search performed in the PubMed, Embase, and ISI databases as fulfilling the inclusion criteria and were reviewed for subject characteristics, radiographic parameters, and salient findings. Studies reviewed suggested that dsMRI was able to detect new appearance or increased grade of medullary compression in greater than or equal to 20 % of patients and to demonstrate an average narrowing of the cervical canal by 20 % (in comparison with the neutral position). Several additional parameters were investigated, but their clinical significance remained unconfirmed; 2 studies examined how surgical decision-making could be affected by the additional findings of dsMRI. The authors concluded that dsMRI represents an available modification of conventional static MRI and is potentially able to demonstrate pathologies that might be previously missed. They stated that evidence suggested that dsMRI can elucidate spinal cord compression with higher sensitivity, resulting in improved diagnostic accuracy of cervical spondylotic myelopathy, which may impact surgical planning for these patients; however, more high-quality studies are needed to further establish its indications to avoid over-diagnosis with this powerful imaging technique.
Magnetic Resonance Imaging in Cervical Spine Clearance of Neurologically Intact Patients With Blunt Trauma
In a meta-analysis, Malhotra and co-workers (2017) quantified the rate of unstable injuries detected by MRI missed on CT in blunt cervical spine (CS) trauma patients and evaluated the utility of MRI in CS clearance. These researchers undertook a systematic review of worldwide evidence across 5 major medical databases. Studies were included if they reported the number of unstable injuries or gave enough details for inference. Variables assessed included severity, CT/MRI specifications, imaging timing, and outcome/follow-up. Pooled incidences of unstable injury on follow-up weighted by inverse-of-variance among all included and obtunded or alert patients were reported. Of 428 unique citations, 23 proved eligible, with 5,286 patients found, and 16 unstable injuries reported in 5 studies. The overall pooled incidence was 0.0029 %. Among studies reporting only obtunded patients, the pooled incidence was 0.017 %. In alert patients, the incidence was 0.011 %. All reported positive findings were critically reviewed, and only 11 could be considered truly unstable. The authors concluded that there was significant heterogeneity in the literature regarding the use of imaging after a negative CT. The finding rate on MRI for unstable injury was extremely low in obtunded and alert patients. They stated that although MRI is frequently performed, its utility and cost-effectiveness needs further study. Key points of this meta-analysis included the following -- There were 16 unstable injuries on follow-up MRI among 5,286 patients. The positive finding rate among obtunded patients was 0.12 %. The positive finding rate among alert, awake patients was 0.72 %. MRI has a high false-positive rate; its utility mandated further studies. The use and role of "confirmatory" tests showed wide variations.
Wu and associates (2018) noted that use of MRI for cervical clearance after a negative cervical CT scan result in alert patients with blunt trauma who are neurologically intact is not infrequent, despite poor evidence in regard to its utility. These investigators evaluated the utility and cost-effectiveness of using MRI versus no follow-up in this patient population. A modeling-based decision analysis was performed during the lifetime of a 40-year old individual from a societal perspective. The 2 strategies compared were no follow-up and MRI. A Markov model with a 3 % discount rate was used with parameters from the literature. Base cases and probabilistic and sensitivity analyses were performed to assess the cost-effectiveness of the strategies. The cost of MRI follow-up was $11,477, with a health benefit of 24.03 quality-adjusted life-years (QALY); the cost of no follow-up was $6,432, with a health benefit of 24.08 QALY. No follow-up was the dominant strategy, with a lower cost and a higher utility. Probabilistic sensitivity analysis showed no follow-up to be the better strategy in all 10,000 iterations. No follow-up was the better strategy irrespective of the NPV of initial CT result, and it remained the better strategy when the incidence of missed unstable injury resulting in permanent neurologic deficits was less than 64.2 % and the incidence of patients immobilized with a hard collar who still received cord injury was greater than 19.7 %. Multiple 3-way sensitivity analyses were performed. The authors concluded that MRI is not cost-effective for further evaluation of unstable injury in neurologically intact patients with blunt trauma after a negative cervical spine CT result.
MRI for Evaluation of Whiplash and Non-Specific Neck Pain
Owens and colleagues (2018) stated that morphometric changes to cervical musculature in whiplash associated disorder have been reported in several studies with varying results. However, the evidence is unclear because only a limited number of cohorts have been studied and one cohort has been reported in multiple publications. In a systematic review with meta-analysis, these researchers evaluated the evidence for cervical muscle morphometric changes on MRI following whiplash. PubMed, Medline and Cochrane Library were searched without language restriction using combinations of the MeSH terms "muscles", "whiplash injuries", and "magnetic resonance imaging". Studies of acute and chronic whiplash were included if they compared whiplash and control cervical spine muscle morphometry measurements from MR images. The search identified 380 studies. After screening, 8 studies describing 5 cohorts (1 acute, 3 chronic, 1 both acute and chronic) met the inclusion criteria. Participant characteristics and outcome measures were extracted using a standard extraction format. Quality of eligible studies was assessed using the Newcastle-Ottawa Scale. Muscle cross-sectional area (CSA) and fat infiltrate (MFI) for acute and chronic whiplash cohorts were compared using mean difference (MD) and 95 % CIs. Meta-analysis models were created when data from more than 2 eligible cohorts was available, using inverse-variance random-effects models (RevMan5 version 5.3.5). Quality assessment was uniformly good; but only 2 studies blinded the assessor. Analysis of the acute cohorts revealed no consensus with respect to CSA; MFI was not measured in the acute cohorts. Analysis of the chronic cohorts revealed CSA was probably increased in some muscles after whiplash, but there was insufficient evidence to confirm whether MFI was also increased. Because the available data were limited, meta-analyses of only multifidus were performed. In chronic whiplash multifidus CSA was significantly increased at C5 (Z = 3.51, p < 0.01) and C6 (Z = 2.66, p < 0.01); and MFI was significantly increased at C7 only (Z = 2.52, p < 0.01); but the heterogeneity was unacceptably high (I2 = 83 %). The authors concluded that the strength of the evidence for cervical muscle morphometric changes on MRI after whiplash was inconsistent for CSA and MFI. They stated that future study designs should be standardized with quantification of 3-dimensional muscle morphometry.
Farrell and colleagues (2019) stated that there is uncertainty regarding the clinical significance of findings on MRI in patients with whiplash associated disorder (WAD) or non-specific neck pain (NSNP). In a systematic review and meta-analysis, these researchers compared the presence of cervical spine MRI findings in people with WAD or NSNP with pain-free controls. Subjects included adults with WAD (n = 994), NSNP (n = 715), or pain-free controls (n = 2,323). Medline, Embase, CINAHL, Web of Science, SCOPUS, and Cochrane CENTRAL databases were searched; 2 independent reviewers identified studies for inclusion and extracted data. Risk of bias was assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Overall quality of the evidence from meta-analysis was assessed using the GRADE approach. Meta-analysis was performed using a random-effects model to calculate odds ratios (ORs) or standard mean differences (SMDs) for binary and continuous data. A total of 31 studies were included (8 comparing acute WAD to controls, 14 comparing chronic WAD to controls, 12 comparing chronic NSNP to controls) comprising 4,032 subjects. Rectus capitis posterior major cross-sectional area (CSA) was smaller in people with chronic NSNP than controls (2 studies: SMD -1.18 [95 % CI: -1.65 to -0.71]). The remaining meta-analysis comparisons showed no group differences in MRI findings. The quality of evidence was mostly low due to small sample sizes and high heterogeneity. The authors concluded that given the typically low-quality evidence, definitive conclusions could not be drawn on the presence of MRI findings in individuals with WAD or NSNP compared with pain-free controls.
Furthermore, an UpToDate review on "Evaluation of the adult patient with neck pain" (Isaac and Kelly, 2019) states that "… MRI imaging should be performed urgently in patients suspected of having an infection, malignancy, or spinal cord compression. In the absence of red flags, imaging is not necessary in patients with mild acute or chronic neck pain that does not limit or interrupt daily activities, does not affect performance of occupation, and is easily ignored when distracted. Patients who have undergone low-velocity neck trauma (e.g., whiplash) also generally do not require imaging". The review said: "Imaging is indicated for patients with persistent moderate to severe neck pain (eg, lasting >6 weeks and affecting sleep or ability to perform daily activities and/or occupation) even if they lack 'red flags.' For most of these individuals (eg, without concern for infection or malignancy, no localizing neurologic symptoms or signs, no major trauma), the preferred initial examination is cervical spine radiography. If there are concerning abnormalities noted on cervical spine radiography (eg, endplate erosion and soft tissue swelling raising concern about discitis/osteomyelitis, bony destruction raising concern about metastases, or bony remodeling suggesting underlying mass), cervical spine MRI without contrast should be performed. MRI is generally not indicated if radiographs are normal or show only degenerative changes."
MRI / CT for Evaluation of Cervical Spinal Injury / Discontinuation of Cervical Collar Use
Veiga and Mitchell (2019) noted that a missed cervical spinal injury could have devastating consequences. Patients with a suspected cervical spinal injury are kept in rigid collars for cervical immobilization. Prolonged collar use has important clinical implications. A well-defined guideline related to the removal of cervical collars from adult obtunded blunt trauma patients has not been developed. These researchers determined if MRI offered a definitive benefit over CT with respect to patient management. They searched Ovid Online, EBSCO, NICE Evidence Journals, Medline, PubMed, BNI, CINAHL and Google Scholar as well as the grey literature. Data extraction and synthesis were performed on studies that compared the radiologic findings and clinical outcomes of CT scan and MRI in this patient group. There is evidence that supports the safe discontinuation of cervical collar use after a negative multi-detector CT scan result alone; MRI may detect a significant number of ligamentous injuries, but such injuries are rarely of clinical significance because they rarely alter clinical management. Its use should be limited to specific circumstances.
Evaluation of Patients With Thoracolumbar Spine Trauma
The Congress of Neurological Surgeons’ systematic review and evidence-based guidelines on "The evaluation and treatment of patients with thoracolumbar spine trauma: Radiological evaluation" (Qureshi et al, 2019) stated that "there was insufficient evidence that MRI can help predict clinical outcomes in patients with acute traumatic thoracic and thoracolumbar spine injuries".
Computed Tomography-Guided Percutaneous Spine Biopsies for Determination of a Causative Organism in Cases of Suspected Infection
Sertic and colleagues (2019) noted that in suspected spondylodiscitis and vertebral osteomyelitis, CT-guided biopsies are often performed to determine a causative organism and guide anti-microbial therapy. These researchers determined the diagnostic culture yield of CT-guided biopsies performed in cases of suspected spinal infections. A literature search of PubMed and Medline up to April 2017 was performed for keywords "CT guided vertebral biopsy infection", "CT-guided spine biopsy infection", "CT guided spine biopsy yield", and "CT guided vertebral biopsy yield". Inclusion criteria primarily consisted of studies exclusively using CT-guided biopsies in cases of suspected infectious lesions only. After study selection, published articles were analyzed to determine diagnostic culture yield; descriptive statistics were applied. A total of 220 search results were screened; 11 met inclusion criteria and were reviewed. A total of 647 biopsies of suspected infectious spinal lesions were performed. Positive cultures were obtained in 241 cases. Upon excluding 1 paper's skewed results, the net pooled results culture yield was 33 %. Several cultures grew multiple organisms, leading to a total of 244 species identified. Most common isolated organisms include Staphylococcus aureus (n = 83), coagulase-negative Staphylococcus (n = 45), and Mycobacteria (n = 38). The authors concluded that the diagnostic culture yield for CT-guided biopsies in cases of suspected spinal infection was low, approximately 33 %. The reasons for this were likely multi-factorial and have not yet been clearly defined, including the effect of pre-administration of antibiotics, biopsy technique, inadequate sample volume, suboptimal specimen transfer methods, and culture techniques. These researchers stated that further study of these individual variables is needed with a clearly defined and universally applied standard reference method. Considering the administration of antibiotics is often delayed in an attempt to first determine a causative organism, the question of clinical utility is raised, especially given the potential consequences of doing so. Advances in technology and hospital policy regarding specimen acquisition and tissue transfer and handling are needed to ensure the benefits of CT-guided biopsies out-weigh the risks. Collaboration between interventional radiologists and pathologists is essential to optimize these techniques to ensure optimal results.
The authors stated that the main drawback of this review was the heterogeneity of metrics in the 11 studies. Unfortunately, it was difficult to evaluate if any particular variable, such as biopsy method or specimen transfer and processing method, had a statistically significant effect on diagnostic culture yield across multiple papers. Another major drawback was that nearly all included studies were retrospective reviews. Lastly, as there exists an imperfect Gold standard for the diagnosis of vertebral osteomyelitis, there was considerable heterogeneity in how each study defined their reference method. Some studies employed a composite reference including microbiological diagnosis or histopathology, radiological appearance, and clinical response to anti-microbial therapy; whereas others utilized positive microbiology or histopathology alone or heavily relied on clinician judgment. This not only made comparison between studies difficult but also made any measure of clinical sensitivity, specificity, or accuracy difficult to determine.
Upright MRI for Evaluation of the Spine
Kern et al (2019) noted that the treatment of patients with spinal stenosis and concurrent degenerative spondylolisthesis is controversial. Two large randomized controlled trials (RCTs) reported contradictory results. These researchers hypothesized that a substantial number of patients will show evidence of micro-instability after a sole decompression procedure. This study was a retrospective analysis of all cases of lumbar spinal stenosis treated at the Frankfurt University Clinic (Universitätsklinik Frankfurt) from 2010 through 2013. Patients who had associated spondylolisthesis underwent upright magnetic resonance imaging (MRI) studies in flexion and extension for identification of subtle signs of micro-instability. Clinical outcome was assessed by means of SF-36 bodily pain (BP) and physical functioning (PF) scales. A total of 21 patients were recruited to undergo upright MRI studies. The mean duration of follow-up was 65 months (SD 16 months). Of these 21 patients, 10 (47 %) showed signs of micro-instability as defined by movement of greater than 4 mm on flexion/extension MRI. Comparison of mean SF-36 BP and PF scores in the group of patients who showed micro-instability versus those who did not showed no statistically significant difference on either scale. The authors concluded that there appeared to be a substantial subset of patients who developed morphological micro-instability after sole decompression procedures but did not experience any clinically significant effect of the instability.
Berry et al (2019) stated that understanding changes in lumbar spine (LS) angles and inter-vertebral disc (IVD) behavior in end-range positions in healthy subjects could provide a basis for developing more specific LS models and comparing people with spine pathology. These researchers quantified three-dimensional (3D) LS angles and changes in IVD characteristics with end-range positions in 3 planes of motion using upright MRI in healthy individuals, and determined which intervertebral segments contributed most in each plane of movement. A total of 13 people (average age of 24.4 years, range of 18 to 51 years; 9 females; body mass index [BMI] = 22.4 ± 1.8 kg/m2) with no history of low back pain (LBP) were scanned in an upright MRI in standing, sitting flexion, sitting axial rotation (left, right), prone on elbows, prone extension, and standing lateral bending (left, right). Global and local intervertebral LS angles were measured. Anterior-posterior (AP) length of the IVD and location of the nucleus pulposus was measured. For the sagittal plane, lower LS segments contributed most to change in position, and the location of the nucleus pulposus migrated from a more posterior position in sitting flexion to a more anterior position in end-range extension. For lateral bending, the upper LS contributed most to end-range positions. Small degrees of intervertebral rotation (1 to 2°) across all levels were observed for axial plane positions. There were no systematic changes in IVD characteristics for axial or coronal plane positions.
Papavero et al (2020) stated that redundant nerve roots (RNRs) are a negative prognostic factor in patients with central lumbar spinal stenosis (LSS); 40 % of candidates for surgical decompression showed RNRs (RNR+) on pre-operative conventional MRI. In a retrospective, observational study, these investigators examined the prevalence of RNRs in 3 functional postures (standing, neutral sitting and flexed sitting) with an upright MRI (upMRI). A total of 30 surgical candidates underwent upMRI. Sagittal and axial T2-weighted images of the 3 functional postures were evaluated. The segmental length of the lumbar spine (sLLS), the lordotic angle (LA) and the dural cross-sectional area (DCSA) were measured in each body position. Generalized linear mixed models were performed; the 0.05 level of probability was set as the criterion for statistical significance. The prevalence of RNRs decreased from 80 % during standing to 16.7 % during flexed sitting (p < 0.001). The sLLS increased significantly from standing to neutral sitting in both RNR groups (p < 0.001). The increase from neutral sitting to flexed sitting was only significant (p < 0.001) for the group without RNRs (RNR-). The LA decreased significantly for both RNR groups from standing to flexed sitting (p < 0.001). The DSCA increased significantly in the RNR- group (p < 0.001) but not in the RNR+ group (p = 0.9). The authors concluded that the prevalence of RNRs was body position-dependent; and increases in DCSA play a determinant role in resolving RNRs.
Shaikh et al (2020) examined the effect of upright, seated, and supine postures on lumbar muscle morphometry at multiple spinal levels and for multiple muscles. A total of 6 asymptomatic volunteers were imaged (0.5 T upright open MRI) in 7 postures (standing, standing holding 8 kg, standing 45° flexion, seated 45° flexion, seated upright, seated 45° extension, and supine), with scans at L3/L4, L4/L5, and L5/S1. Muscle CSA and muscle position with respect to the vertebral body centroid (radius and angle) were measured for the multifidus/erector spinae combined and psoas major muscles. Posture significantly affected the multifidus/erector spinae CSA with decreasing CSA from straight postures (standing and supine) to seated and flexed postures (up to 19 %). Psoas major CSA significantly varied with vertebral level with opposite trends due to posture at L3/L4 (increasing CSA, up to 36 %) and L5/S1 (decreasing CSA, up to 40 %) with sitting/flexion. For both muscle groups, radius and angle followed similar trends with decreasing radius (up to 5 %) and increasing angle (up to 12 %) with seated/flexed postures. CSA and lumbar lordosis had some correlation (multifidus/erector spinae L4/L5 and L5/S1, r = 0.37 to 0.45; PS L3/L4 left, r = - 0.51). There was generally good repeatability (average ICC (3, 1): posture = 0.81, intra = 0.89, inter = 0.82). The authors concluded that changes in multifidus/erector spinae muscle CSA likely represented muscles stretching between upright and seated/flexed postures . For the psoas major, the differential level effect suggested that changing 3D muscle morphometry with flexion was not uniform along the muscle length. The muscle and spinal level-dependent effects of posture and spinal curvature correlation, including muscle CSA and position, highlighted considering measured muscle morphometry from different postures in spine models.
In an observational study, Rustagi et al (2020) examined if there were differences in spine structure measures between experimental postures and standard supine posture MRIs. A total of 34 LBP patients were included. MRI was taken in 6 experimental postures. The dependent measures includes sagittal view anterior (ADH), middle and posterior disc heights, thecal sac width, left/right foraminal height (FH). In the axial view: disc width, left and right foraminal height. Measures were done L3/L4, L4/L5 and L5/S1. Each subject served as their own control. Spine measurements in the experimental posture were compared to the same measures in the standard supine posture; 94 % inter-observer reliability was observed. In the sagittal and axial view, 55 of the 108 and 11 of the 18 measures were significantly different. In sagittal view: (i) ADH was significantly smaller in the sitting flexed posture by 2.50 mm ± 0.63 compared to the supine posture; (ii) ADH in sitting neutral posture was significantly smaller than the standard posture by 1.97 mm ± 0.86; (iii) sitting flexed posture showed that bilateral FH measures were significantly different; (iv) Bilateral FH was larger in the sitting neutral posture compared to the standard supine posture by 0.87 mm ± 0.17. The authors concluded that this research quantified the differences in spine structure measures that occurred in various experimental postures. The additional information gathered from an upright MRI may correlate with symptoms leading to an accurate diagnosis and assist in future spine research.
MRI / CT for the Diagnosis and Evaluation of Lumbar Epidural Lipomatosis
Ishikawa and associates (2006) stated that idiopathic symptomatic spinal epidural lipomatosis (SEL) is a rare condition, and few reports have discussed diagnostic imaging criteria. These researchers examined factors relating to its clinical symptoms, correlations between clinical features and the presence of spinal epidural fat, and reviewed the literature concerning idiopathic SEL. Morphological gradings of epidural fat were examined in 7 patients with idiopathic SEL by using MRI. Furthermore, BMI, the number of involved vertebral levels, grade, and pre-operative Japanese Orthopedic Association (JOA) score were analyzed. Surgery resulted in symptomatic relief, with a mean JOA score recovery rate of 67.4 %. Grading of epidural fat tended to display a slight negative correlation with pre-operative JOA score, whereas a strong significant positive correlation was found between the number of involved vertebral levels and BMI. The authors concluded that the number of involved vertebral levels and obesity were strongly correlated, whereas severity of dural compression was not always significantly associated with neurological complications. They stated that these findings indicated that epidural fat of the lumbar spine contributed to neurological deficits. In addition, weight-reduction therapy appeared to decrease the number of vertebral levels involved; and MRI-based grading is helpful for the diagnosis and evaluation of idiopathic lumbar SEL. Moreover, symptoms and neurological findings were important for determining the surgical approach.
Gerardy and colleagues (2021) noted that SEL is a rare condition characterized by excessive accumulation of normal fat in the epidural space. These investigators presented the findings of a retrospective study of the charts of 20 patients (17 men and 3 women); average age of 64 years. Subjects suffered from radiculopathy and/or neurogenic claudication. Lipomatosis was idiopathic in 6 patients and secondary in 14 patients. Lipomatosis was MRI grade-II in 30 % of cases and grade-III in 70 % of cases. subjects have all improved following decompressive surgery by laminectomy and resection of epidural fat. According to the authors’ experience and to the literature, surgical decompression is a safe and effective procedure for patients with symptomatic lumbar epidural lipomatosis in case of failure of conservative treatment or in case of neurological deficits.
Walker and co-workers (2021) stated that SEL is caused by an excess of adipose tissue accumulation localized to the thoracic and lumbar regions of the spine. While the exact pathogenesis is unclear, the etiology of SEL can be broadly classified based on 5 commonly associated risk factors: exogenous steroid use, obesity, endogenous steroid hormonal disease, spine surgery, and idiopathic disease. Progression of SEL may lead to neurological deficits, myelopathy, radiculopathy, neurogenic claudication, loss of sensation, difficulty voiding, lower extremity weakness, and rarely cauda equina syndrome. These investigators noted that the diagnosis of SEL can be challenging given that symptoms often resemble other common etiologies such as vertebral and disc disease. Given this overlap, diagnosis requires a high degree of clinical suspicion and various diagnostic modalities. The most sensitive test is advanced imaging, specifically T1-weighted MRI. Grading patterns of SEL were defined based on the epidural fat (EF) to spinal column (Spi C) index, with normal being less than or equal to 40 % and grading of SEL being described as grade I, II, or III; with grade-III being characterized by an EF/Spi C index of greater than or equal to 75 %.
Spinnato et al (2022) noted that SEL is defined as the abnormal accumulation of unencapsulated adipose tissue in the spinal epidural space. SEL can be asymptomatic or can cause a wide range of symptoms, the most common of which is neurogenic claudication. Several other neurological manifestations may also occur, above all myelopathy and radicular symptoms. The spinal level most frequently involved in patients with SEL is the lumbar one, followed by the thoracic one. Imaging plays a key role in the disease assessment. MRI is considered the most effective and sensitive modality for diagnosing and staging SEL. Anyway, also CT scan can diagnose SEL. The diagnosis may be incidental (in mild-moderate disease) or may be taken into account in cases with neurological symptoms (in moderate-severe disease). There are some recognized risk factors for SEL, the most common of which are exogenous steroid use and obesity. Recent studies have found an association between SEL and obesity, hyperlipidemia and liver fat deposition. As a matter of fact, SEL can be considered the spinal hallmark of metabolic syndrome. Risk factors control represents the initial treatment strategy in patients with SEL (e.g., weight loss, steroid therapy suspension). Surgical decompression may be needed when conservative treatment fails or when the patient develops acute/severe neurological symptoms.
Furthermore, an UpToDate review on “Polyradiculopathy: Spinal stenosis, infectious, carcinomatous, and inflammatory nerve root syndromes” (Rutkove and Tarulli, 2022) states that “Additional causes of spinal stenosis include congenital conditions, such as hereditary spinal stenosis or achondroplasia, systemic conditions such as ankylosing spondylitis or Paget disease, and excess accumulation of epidural fat (epidural lipomatosis), which can be seen in patients with Cushing disorder, exogenous glucocorticoid exposure, or obesity … Magnetic resonance imaging (MRI) has become the test of choice in the evaluation of spinal stenosis, although bony changes such as osteophyte formation are better demonstrated by computed tomography (CT)”.
Dual-Energy CT for the Evaluation of Bone Marrow Edema and Fracture Lines in Acute Vertebral Fractures
Backer and associates (2021) stated that in vertebral injuries, prompt diagnosis is essential to avoid any delays in treatment. Conventional radiography may only reveal indirect signs of fractures, such as when it is displaced; thus, to detect the presence of bone marrow edema (BME) or disc edema, adjunctive tools are needed, such as MRI or dual-energy computed tomography (DE-CT). In a systematic review and meta-analysis, these researchers examined the sensitivity, specificity, and accuracy of DE-CT of bone marrow edema and disc edema in spine injuries. Search terms included ((DECT) OR (DE-CT) OR (dual-energy CT) OR "Dual energy CT" OR (dual-energy computed tomography) OR (dual energy computed tomography)) AND ((spine) OR (vertebral)), and the PubMed, Embase, and Medline databases and the Cochrane Library and Google were used. These investigators found 1,233 articles on their preliminary search, but only 13 articles met all criteria. Data were extracted to calculate the pooled sensitivity, specificity, and diagnostic odds ratio (DOR) for analysis using R software. Within the 13 studies, 515 patients, 3,335 vertebrae, and 926 acute fractures (27.8 %) defined by MRI were included. The largest cohort included 76 patients with 774 vertebrae. In 12 publications, MRI was reported for comparison. For DE-CT, the overall sensitivity was 86.2 % with a specificity of 91.2 % and accuracy of 89.3 %. Furthermore, 5 studies reported the accuracy of CT with an overall sensitivity of 81.3 %, specificity of 80.7 %, and accuracy with 80.9 %. Significant differences were found for specificity (p < 0.001) and accuracy (p = 0.023); however, significant inter-observer differences were reported. The authors concluded that DE-CT appeared to be a promising diagnostic tool for the detection of BME and disc edema, which can potentially replace the current gold standard, the MRI. Level of Evidence = II.
The authors stated that this review had several drawbacks. First, 4 studies were carried out by 1 research group; and individual findings for the different observers were not consistently reported. Second, only a few studies reported both the intra-observer and inter-observer reliability. Third, different kinds of MRI were used as gold standards for comparison to detect BME and disc edema. Fourth, although all studies wanted to report the accuracy of DE-CT, the studies did not use the same reconstruction algorithms or cut-offs across the board, making comparison difficult. Fifth, the largest cohort included only 76 patients.
Cavallaro and colleagues (2022) compared DE-CT and MRI for evaluating the presence and extent of traumatic BME and fracture line depiction in acute vertebral fractures. A total of 88 consecutive patients who underwent dual-source DE-CT and 3-T MRI of the spine were retrospectively analyzed. A total of 5 radiologists examined all vertebrae for presence and extent of BME and for identification of acute fracture lines on MRI and, after 12 weeks, on DE-CT series. Furthermore, image quality, image noise, and diagnostic confidence for overall diagnosis of acute vertebral fracture were assessed. Quantitative analysis of CT numbers was carried out by a 6th radiologist. Two radiologists analyzed MRI and grayscale DE-CT series to define the reference standard. For evaluating BME presence and extent, DE-CT showed high sensitivity (89 % and 84 %, respectively) and specificity (98 % in both), and similarly high diagnostic confidence compared to MRI (2.30 versus 2.32; range of 0 to 3) for the detection of BME (p = 0.72). For evaluating acute fracture lines, MRI achieved high specificity (95 %), moderate sensitivity (76 %), and a significantly lower diagnostic confidence compared to DE-CT (2.42 versus 2.62, range of 0 to 3) (p < 0.001). A cut-off value of - 0.43 HU provided a sensitivity of 89 % and a specificity of 90 % for diagnosing BME, with an overall AUC of 0.96. The authors concluded that the findings of this study demonstrated that both DE-CT and MRI provided high diagnostic confidence and image quality for the evaluation of acute vertebral fractures in general. DE-CT provided, by means of virtual non-calcium (VNCa) reconstructions, high diagnostic accuracy for evaluating the presence and extent of vertebral BME. MRI showed moderate sensitivity and lower confidence for the depiction of fracture lines. Thus, DE-CT may represent a potential imaging alternative to MRI in specific settings of acute spinal trauma, especially in elderly or unstable patients and in cases of subtle or complex orientated fracture lines.
The authors stated that this study had several drawbacks. First, despite the relatively short examination interval, different findings between the 2 modalities concerning BME extent could not be completely excluded. BME, albeit slowly, changes over time, also depending on the adopted therapy. Second, these researchers did not separate thoracic and lumbar vertebrae, nor did they distinguish osteoporotic from non-osteoporotic patients. Age and type of vertebra have been considered as potential factors influencing bone marrow composition, and differences in bone mineral density (BMD) could influence attenuation values on VNCa images. All these factors could potentially influence BME evaluation and CT numbers on VNCa series. These researchers stated that future studies in specific population subgroups could aid in assessing the real impact of these factors in clinical routine. Third, bone marrow changes could be caused by pathologies other than trauma such as malignancy or infection. However, to the best of the authors’ knowledge, other potential causes of bone marrow alteration were not present in this cohort. Finally, results and conclusions were only applicable to the vendor-specific dual-source DE-CT technique and post-processing software, as well as to the employed imaging protocols, which are routinely used in the authors’ department in case of spinal trauma. Particularly in the evaluation of fracture lines, alternative MRI protocols could have performed differently, for instance by using diverse slice thickness or sequences such as T1 spoiled gradient-echo or ultra-short echo time sequences, which have recently been shown to provide image quality comparable to CT for the evaluation of certain bone pathologies of the spine.
Bone Density Measurements on CT or MRI versus DEXA Scan
Ahmad et al (2023) stated that novel methods of bone density assessment using CT and MRI have been increasingly reported in the spine surgery literature. Correlations between these newer measurements and traditional dual energy X-ray absorptiometry (DXA) is unclear. In a systematic review, these investigators examined correlations between BMD from CT or MRI and DXA. Studies published between 2011 and 2021 that reported correlations between the CT- Hounsfield unit (HU) or MRI measurements to DXA t-scores or BMD of lumbar spine or hip were included in this systematic review. A total of 25 studies (15 CT, 10 MRI) met the inclusion criteria with a total number of 2,745 patients. The pooled correlation coefficient of spine CT-HU versus spine DXA, spine CT-HU versus hip DXA and spine CT-HU versus lowest t-score were 0.60, 0.50 and 0.60, respectively. Regarding spine DXA parameters, the pooled r2 for spine CT-HU versus spine t-score was 0.684 and spine CT-HU versus spine BMD was 0.598. In addition, in patients undergoing spine surgery in 4 studies, the pooled correlation between spine CT and spine DXA was (r2: 0.64). In MRI studies, the pooled r2 of spine MRI versus spine DXA and spine MRI versus hip DXA were -0.41 and -0.44, respectively. The authors concluded that CT-HU exhibited stronger correlations with DXA than MRI measurements. Lumbar CT-HU has the highest pooled correlation (r2 = 0.6) with both spine DXA and lowest skeletal t-score followed by lumbar CT-HU with hip DXA (r2 = 0.5), and lumbar MRI with hip (r2 = 0.44) and spine (r2 = 0.41) DXA. Both imaging modalities achieved only a moderate correlation with DXA. Few studies in both modalities have examined the correlation in spine surgery populations and the available data demonstrated that the correlations were worse in the degenerative spine population. A careful interruption of CT-HU and MRI measurement when evaluation of BMD as they only moderately correlated with DXA scores. At this time, it is unclear which modality is a better predictor of mechanical complications and clinical outcomes in spine surgery patients.
Osteoporotic Vertebrae Fracture Risk Measured by Quantitative Computed Tomography
In a systematic review and meta-analysis, Chen et al (2023) compared the use of quantitative CT (QCT) and DXA in the evaluation of osteoporosis with vertebral fracture and osteoporosis without fracture. It has been reported that the volumetric BMD (vBMD) measured by QCT exhibits a stronger correlation with fracture risk than areal BMD (aBMD) measured by DXA. These investigators examined the ability of QCT and DXA to distinguish between osteoporosis with vertebral fracture and osteoporosis without fracture according to vBMD and aBMD. They carried out a primary literature search of the online databases up to July 3, 2022, in both English and Chinese publications, combining synonyms for "QCT", "DXA", and "osteoporosis". The Newcastle-Ottawa scale (NOS) was used to assess the quality of the selected articles. vBMD obtained via QCT and aBMD obtained via DXA were extracted, and were analyzed by Review Manager 5.4 and RStudio. A total of 6 studies with 610 individuals aged 45 to 90 years, of which 179 had vertebral fractures, were included in the final analysis. The weighted MD (WMD) between osteoporosis with vertebral fracture and osteoporosis without fracture for vBMD was - 27.08 (95 % CI: - 31.24 to - 22.92), while for aBMD was - 0.05 (95 % CI: - 0.08 to - 0.03). The authors concluded that both vBMD detected by QCT and aBMD detected by DXA could discriminate fracture status in the spine, and vBMD performed a stronger correlation with fracture risk.
Comparative Effectiveness of 4 Techniques for Identifying Vertebral Fragility Fractures
Ma et al (2024) noted that the incidence of vertebral fragile fractures peaked among the elderly population, and identifying individuals at high risk of vertebral fractures and promptly instituting preventions are of critical importance. These investigators examined the effectiveness and values of Hounsfield unit (HU) values, vertebral bone quality (VBQ) scores, BMD measured by DXA, and QCT to discriminate between patients with and without vertebral fractures. They carried out a thorough search across PubMed, Embase, Cochrane Library, Web of Science, CNKI, and Wan Fang Database to identify potential studies that met the eligibility criteria. Studies that examined the use of HU values, VBQ scores, QCT-measured BMD, and DXA-measured BMD in discriminating vertebral fractures were qualified. The combined results showed that there were significant differences in HU values, VBQ scores, QCT-measured BMD, and DXA-measured BMD between the fracture and non-fracture groups. Moreover, the pooled sensitivity, specificity, and AUC of HU values were 0.82, 0.67, and 0.76, respectively; the pooled sensitivity, specificity, and AUC of VBQ scores were 0.70, 0.75, and 0.78; the pooled sensitivity, specificity, and AUC of QCT-measured BMD were 0.85, 0.76 and 0.88. The authors concluded that all 4 methods, namely HU values, VBQ scores, QCT-measured BMD, and DXA-measured BMD can effectively distinguish between patients with and without vertebral fragile fractures. Among these, QCT-measured BMD exhibited a relatively high effectiveness in discriminating vertebral fractures. VBQ scores and HU values showed comparable effectiveness for discriminating vertebral fractures among elderly patients.
Imaging Techniques for Early Diagnosis and Management of Axial Spondyloarthritis
Jeon and Min (2024) presented recent finding of imaging studies employed for early diagnosis and management of patients with axial spondyloarthritis (axSpA). Using low-dose whole spine CT (CT syndesmophyte score [CTSS]) improved diagnostic accuracy for evaluating spinal structural progression than previous method (modified Stoke Ankylosing Spondylitis Spinal Score [mSASSS]) in axSpA. The novel definition of positive finding of sacroiliac joint (SIJ) and spine MRI allowed diagnosis of axSpA earlier than plain radiography. Furthermore, novel MRI protocol such as volumetric interpolated breath-hold examination improved detection rate of structural change of axial joints in axSpA, Nuclear medicine imaging showed potential for diagnosis and predicting progression of axSpA. Ultrasonography (US)-guided injection is useful for controlling local joint pain of axSpA. AxSpA is characterized by pain and inflammation of axial joints such as the SIJ and spine. Detection of active inflammatory lesions using MRI has expanded the subtypes of axSpA to include non-radiographic axSpA (nr-axSpA). Additionally, many other imaging techniques have improved, and can now detect structural and early inflammatory lesions of the axial joints. Furthermore, a method for quantitative measurement of syndesmophytes by CTSS has been developed; this method is more accurate and sensitive than the mSASSS for detecting spinal structural damage.
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