Thermography

Number: 0029

Policy

Aetna considers thermography (including digital infrared thermal imaging, magnetic resonance (MR) thermography and temperature gradient studies) experimental and investigational for all indications including the following (not an all-inclusive list) because available medical literature indicates thermography to be an ineffective diagnostic technique:

  • Assessment of myofascial trigger points
  • Detection and screening for breast cancer
  • Detection of rupture-prone vulnerable coronary plaque
  • Determination of the efficacy of stroke rehabilitation
  • Diagnosis of complex regional pain syndrome
  • Diagnosis of musculoskeletal injuries
  • Diagnosis and management of vasculitis
  • Early identification of skin neoplasms
  • Esophageal monitoring
  • Evaluation of acute skin toxicity of breast radiotherapy
  • Evaluation of burn wounds
  • Evaluation of dry eye disease
  • Evaluation of leprosy
  • Evaluation and monitoring of individuals with Emery-Dreifuss muscular dystrophy
  • Joint assessment in individuals with inflammatory arthritis
  • Management of infantile hemangioma
  • Monitoring of diabetes mellitus
  • Pre- and peri-operative management of hidradenitis suppurativa
  • Prediction and detection of pressure ulcers
  • Prognosis of post-herpetic neuralgia
  • Screening for adolescent idiopathic scoliosis.

Aetna considers dynamic infrared blood perfusion imaging (DIRI) for intra-operative and post-operative perfusion assessment (e.g., assessment of skin blood perfusion in cranioplasty and flap evaluation) experimental and investigational because of insufficient evidence regarding its clinical effectiveness.

Background

Thermography

Thermography is the measurement of temperature variations at the body surface.  The scientific evidence suggests that thermography may only confirm the presence of a temperature difference, and that other procedures are needed to reach a specific diagnosis.  Thermography may add little to what doctors already know based on history, physical examination, and other studies.

Thermography studies are non-invasive imaging techniques that are intended to measure the skin surface temperature distribution of various organs and tissues.  The infrared radiation from the tissues reveals temperature variations by producing brightly colored patterns on a liquid crystal display.  Interpretation of the color pattern is thought to contribute to the diagnosis of many disorders including breast cancer, Raynaud's phenomenon, digital artery vasospasm, impaired spermatogenesis in infertile men, deep vein thrombosis, reflex sympathetic dystrophy/complex regional pain syndrome, vertebral subluxation, and others.

In contrast to the skin surface thermography techniques used by some chiropractors and other providers, a newer invasive test called a temperature gradient study involves an intravenous catheter.  The catheter is threaded into the coronary arteries to directly measure temperature differences on the inner artery walls.  Researchers believe this information may be related to the presence of unstable coronary artery plaques and could be useful in diagnosing vulnerable patients.  Madjid et al (2006) have shown that inflamed atherosclerotic plaques are hot and their surface temperature correlates with an increased number of macrophages and decreased fibrous-cap thickness.  Multiple animal and human experiments have shown that temperature heterogeneity correlates with arterial inflammation in vivo.  Several coronary temperature mapping catheters are currently being developed and studied.  These thermography methods can be used in the future to detect vulnerable plaques, potentially to determine patients' prognosis, and to study the plaque-stabilizing effects of different medications.

A number of medical authorities have concluded that thermography has no proven medical value, including the American Medical Association, the Office of Health Technology Assessment (OHTA), and the American Academy of Neurology. Based on a study by the OHTA, the Health Care Financing Administration (now the Center for Medicare and Medicaid Services) withdrew Medicare coverage of thermography.

Devices that have been used for thermography skin temperature differential analysis include the Nervoscope, the Temp-O-Scope, and the Neurocalometer.

There is insufficient evidence for the use of thermography for detection of breast cancer.  A structured evidence review of thermography for breast cancer (Kerr, 2004) reached the following conclusions: "The evidence that is currently available does not provide enough support for the role of infrared thermography for either population screening or adjuvant diagnostic testing of breast cancer.  The major gaps in knowledge at this time can only be addressed by large-scale, prospective randomised trials.  More robust research on the effectiveness and costs of technologically advanced infrared thermography devices for population screening and diagnostic testing of breast cancer is needed, and the conclusions of this review should be revisited in the face of additional reliable evidence".

Other reviews have also found a need for additional research on thermography.  Kennedy et al (2009) noted that thermography was first introduced as a screening tool for breast cancer in mid-1950s.  However, after a 1977 study found thermography to lag behind other screening tools, the medical community lost interest in this diagnostic approach.  These researchers discussed each screening tool with a focus brought to thermography.  They stated that no single diagnostic tool provides excellent predictability; however, a combination that incorporates thermography may boost both sensitivity as well as specificity.  The authors concluded that in light of technological advances and maturation of the thermographical industry, more research is needed to confirm the potential of thermography in providing an effective non-invasive, low-risk adjunctive tool for the early detection of breast cancer.

Mammography is currently the gold standard for breast cancer screening.  Thus, sensitivities, specificities, as well as positive and negative predictive values of thermography need to be compared with those of mammography in order to ascertain if thermography is equivalent or superior to mammography.  Presently, there is a lack of scientific data comparing the 2 screening techniques.  In addition, there are no published evidence-based practice guidelines and/or position statements that recommend thermography as the appropriate method of screening for early detection of breast cancer.

Arora et al (2008) examined the effectiveness of a non-invasive digital infrared thermal imaging (DITI) system in the detection of breast cancer.  A total of 92 patients for whom a breast biopsy was recommended based on prior mammogram or ultrasound underwent DITI.  Three scores were generated:
  1. an overall risk score in the screening mode,
  2. a clinical score based on patient information, and
  3. assessment by artificial neural network. 

Sixty of 94 biopsies were malignant and 34 were benign.  Digital infrared thermal imaging identified 58 of 60 malignancies, with 97 % sensitivity, 44 % specificity, and 82 % negative predictive value depending on the mode used.  Compared to an overall risk score of 0, a score of 3 or greater was significantly more likely to be associated with malignancy (30 % versus 90 %, p < 0.03).  The author concluded that DITI is a valuable adjunct to mammography and ultrasound, especially in women with dense breast parenchyma.  Moreover, the authors reported a high negative predictive value for thermography where "the location of the lesion under question based on prior imaging was assessed to generate a positive or negative clinical assessment", i.e., where they were unblinded to the results of the prior mammography or ultrasound.  The specificity was only 11 % and the negative predictive value of thermography was only 66 % in the blinded screening mode.  Furthermore, the authors stated that DITI is not currently recommended or approved as a substitute for screening mammography, and correlation of findings on DITI should be made with alternative imaging techniques.  They stated that further studies are needed using a representative screening population of persons who have not been selected for biopsy based upon prior imaging results.

An American Cancer Society report Mammograms and Other Breast Imaging Procedures (2010) stated that "[t]hermography is a way to measure and map the heat on the surface of the breast using a special heat-sensing camera.  It is based on the idea that the temperature rises in areas with increased blood flow and metabolism, which could be a sign of a tumor.  Thermography has been around for many years, and some scientists are still trying to improve the technology to use it in breast imaging.  But no study has ever shown that it is an effective screening tool for finding breast cancer early.  It should not be used as a substitute for mammograms.  Newer versions of this test are better able to find very small temperature differences.  They may prove to be more accurate than older versions, and are now being studied to find out if they might be useful in finding cancer".  Thermography is listed under "newer and experimental breast imaging methods" in this report. 

Additionally, the United Kingdom's NHS Cancer Screening Programmes (2010) stated that "thermography is not a replacement for mammography.  It is a relatively new test and isn't reliable enough to use either to diagnose or screen for cancer.  Mammography is still the best test and is used as a world wide standard for breast screening in women over 50".

The Food and Drug Administration (FDA, 2011) stated that breast thermography should not be used instead of mammography, noting that thermography has not been approved as a stand-alone tool for breast cancer screening or diagnosis.  Telethermographic devices produce infrared images and do not require exposure to radiation or breast compression, which some healthcare providers claim make them superior to mammographic devices.  However, the FDA stated that "there is simply no evidence" that breast thermography can take the place of mammography.  The agency has sent warning letters to manufacturers and practitioners who have made misleading claims about breast thermography use.

Currently, there is insufficient evidence to support the use of thermography for the diagnosis of complex regional pain syndrome (CRPS).  The use of thermography in the diagnosis of CRPS type 1 (CRPS1) is based on the presence of temperature asymmetries between the involved area of the extremity and the corresponding area of the uninvolved extremity.  However, the interpretation of thermographical images is subjective and not validated for routine use.  Huygen et al (2004) developed a sensitive, specific and reproducible arithmetical model as the result of computer-assisted infra-red thermography in patients with early stage CRPS1 in one hand.  Eighteen patients with CRPS1 on one hand and 13 healthy volunteers were included in the study.  The severity of the disease was determined by means of pain questionnaires [visual analogue scale (VAS) pain and McGill Pain Questionnaire], measurements of mobility (active range of motion) and edema volume.  Asymmetry between the involved and the uninvolved extremities was calculated by means of the asymmetry factor, the ratio and the average temperature differences.  The discrimination power of the 3 methods was determined by the receiver-operating curve (ROC).  The regression between the determined temperature distributions of both extremities was plotted.  Subsequently the correlation of the data was calculated. In normal healthy individuals the asymmetry factor was 0.91 (0.01) (SD), whereas in CRPS1 patients this factor was 0.45 (0.07) (SD).  The performance of the arithmetic model based on the ROC curve was excellent.  The area under the curve was 0.97 (p < 0.001), the sensitivity and specificity was 9 2% and 94 %, respectively.  Furthermore, the temperature asymmetry factor was correlated with the duration of the disease and VAS pain.

Gradl and colleagues (2003) stated that CRPS1 represents a frequent complication following distal radial fractures.  These investigators studied the value of clinical evaluation, radiography and thermography in the early diagnosis of CRPS1.  A total of 158 patients with distal radial fractures were followed-up for 16 weeks after trauma.  Apart from a detailed clinical examination 8 and 16 weeks after trauma, thermography and bilateral radiographs of both hands were carried out.  At the end of the observation period 18 patients (11 %) were clinically identified as CRPS1.  The severity of the preceding trauma and the chosen therapy did not influence the process of the disease.  Sixteen weeks after trauma easy differentiation between normal fracture patients and CRPS1 patients was possible.  Eight weeks after distal radial fracture clinical evaluation showed a sensitivity of 78 % and a specificity of 94 %.  On the other hand, thermography (58 %) and bilateral radiography (33 %) revealed poor sensitivities.  The specificity was high for radiography (91 %) and again poor for thermography (66 %).  These authors concluded that the results of the study support the importance of clinical evaluation in the early diagnosis of CRPS1.  Plain radiographs facilitate the diagnosis as soon as bony changes develop.

Arterial wall thermography has also been used to identify rupture-prone vulnerable coronary plaque.  However, the clinical value of arterial thermography in interventional cardiology has not been established.

Schaar and colleagues (2007) noted that rupture of vulnerable plaques is the principal cause of acute coronary syndrome and myocardial infarction.  Identification of vulnerable plaques is therefore essential to enable the development of treatment modalities to stabilize such plaques.  Thermography is one of the several novel methods being examined for detecting vulnerable plaques.  It evaluates the temperature heterogeneity as an indicator of the metabolic state of the plaque.  The authors concluded that while several invasive and non-invasive techniques are currently under development to assess vulnerable plaques, none has proven its value in an extensive in-vivo validation and all have a lack of prospective data.

García-García and colleagues (2008) stated that thin-capped fibroatheroma is the morphology that most resembles plaque rupture.  Detection of these vulnerable plaques in-vivo is essential to being able to study their natural history and evaluate potential treatment modalities and, therefore, may ultimately have an important impact on the prevention of acute myocardial infarction and death.  The investigators reported that, currently, conventional grayscale intra-vascular ultrasound, virtual histology and palpography data are being collected with the same catheter during the same pullback.  A combination of this catheter with either thermography capability or additional imaging, such as optical coherence tomography or spectroscopy, would be an exciting development.  Intra-vascular magnetic resonance imaging also holds much promise.  The investigators stated that, to date, none of the techniques described above has been sufficiently validated and, most importantly, their predictive value for adverse cardiac events remains elusive.  The investigators concluded that very rigorous and well-designed studies are needed for defining the role of each diagnostic modality.  Until researchers are able to detect in-vivo vulnerable plaques accurately, no specific treatment is warranted.

Madjid and colleagues (2006) stated that up to 2/3 of acute myocardial infarctions develop at sites of culprit lesions without a significant stenosis.  New imaging techniques are needed to identify those lesions with an increased risk of developing an acute complication in the near future.  Inflammation is a hallmark feature of these vulnerable/high-risk plaques.  These investigators have demonstrated that inflamed atherosclerotic plaques are hot and their surface temperature correlates with an increased number of macrophages and reduced fibrous-cap thickness.  They noted that animal and human studies have reported that temperature heterogeneity correlates with arterial inflammation in-vivo.  Several coronary temperature mapping catheters are currently being developed.  These thermographic methods can be used in the future to detect vulnerable plaques, potentially to ascertain patients' prognosis, and to examine the plaque-stabilizing effects of various pharmacotherapies.

Sharif and Murphy (2010) noted that critical coronary stenoses have been shown to contribute to only a minority of acute coronary syndromes and sudden cardiac death.  Autopsy studies have identified a subgroup of high-risk patients with disrupted vulnerable plaque and modest stenosis.  Consequently, a clinical need exists to develop methods to identify these plaques prospectively before disruption and clinical expression of disease.  Recent advances in invasive as well as non-invasive imaging techniques have shown the potential to identify these high-risk plaques.  The anatomical characteristics of the vulnerable plaque such as thin cap fibro-atheroma and lipid pool can be identified with angioscopy, high frequency intra-vascular ultrasound, intra-vascular magnetic resonance imaging (MRI), and optical coherence tomography.  Efforts have also been made to recognize active inflammation in high-risk plaques using intra-vascular thermography.  Plaque chemical composition by measuring electro-magnetic radiation using spectroscopy is also an emerging technology to detect vulnerable plaques.  Non-invasive imaging with MRI, computed tomography, and positron emission tomography also holds the potential to differentiate between low-risk and high-risk plaques.  However, at present none of these imaging modalities is able to detect vulnerable plaque nor have they been shown to definitively predict outcome.  Nevertheless in contrast, there has been a parallel development in the physiological assessment of advanced athero-sclerotic coronary artery disease.  Thus, recent trials using fractional flow reserve in patients with modest non flow-limiting stenoses have shown that deferral of percutaneous coronary intervention with optimal medical therapy in these patients is superior to coronary intervention.  The authors concluded that further trials are needed to provide more information regarding the natural history of high-risk but non flow-limiting plaque to establish patient-specific targeted therapy and to refine plaque stabilizing strategies in the future.

There is insufficient evidence to support the use of thermography in post-herpetic neuralgia.  Han and associates (2010) examined the usefulness of infrared thermography as a predictor of post-herpetic neuralgia (PHN).  Infrared thermography was performed on the affected body regions of 110 patients who had been diagnosed with acute herpes zoster (HZ).  Demographical data collected included age, gender, time of skin lesions onset, development of PHN, and co-morbidities.  The temperature differences between the unaffected and affected dermatome were calculated.  Differences greater than 0.6 degrees C for the mean temperature across the face and trunk were considered abnormal.  The affected side was warmer in 35 patients and cooler in 33 patients than the contralateral side.  A patient's age and disease duration affected treatment outcomes.  However, the temperature differences were not correlated with pain severity, disease duration, allodynia, development of PHN, and use of anti-viral agents (p > 0.05).  The authors concluded that a patient's age and disease duration are the most important factors predicting PHN progression, irrespective of thermal findings, and PHN can not be predicted by infrared thermal imaging.

An Agency for Healthcare Research and Quality's report on non-invasive diagnostic techniques for the detection of skin cancers (Parsons et al, 2011) listed thermography as one of the investigational diagnostic techniques for the detection of skin cancers.

Kontos et al (2011) determined the sensitivity and specificity of DITI in a series of women who underwent surgical excision or core biopsy of benign and malignant breast lesions presenting through the symptomatic clinic.  Digital infrared thermal imaging was evaluated in 63 symptomatic patients attending a 1-stop diagnostic breast clinic.  Thermography had 90 true-negative, 16 false-positive, 15 false-negative and 5 true-positive results.  The sensitivity was 25 %, specificity 85 %, positive-predictive value 24 %, and negative-predictive value 86 %.  The authors concluded that despite being non-invasive and painless, because of the low sensitivity for breast cancer, DITI is not indicated for the primary evaluation of symptomatic patients nor should it be used on a routine basis as a screening test for breast cancer.

The Canadian Agency for Drugs and Technologies in Health’s technology assessment on  Infrared thermography for population screening and diagnostic testing for breast cancer” (Morrison, 2012) states that “No randomized controlled trials have been conducted that compare the effectiveness of thermography with mammography for screening in well women, and there is no evidence regarding the cost-effectiveness of thermography used for screening.  Prospective cohort studies of symptomatic patients or patients with abnormal mammograms or ultrasounds do not provide the type of evidence needed to justify the use of thermography for breast screening.  Results indicate that thermography performance is worse than mammography in terms of sensitivity, specificity, and predictive values; however, some of the studies’ authors have suggested there may be a role for thermography as an adjunct diagnostic test in some cases”.

Kim et al (2012) evaluated the accuracy of the size and location of the ablation zone produced by volumetric MRI-guided high-intensity focused ultrasound (HIFU) ablation of uterine fibroids on the basis of MR thermometric analysis and assessed the effects of a feedback control technique.  A total of 33 women with 38 uterine fibroids were treated with an MR imaging-guided HIFU system capable of volumetric feedback ablation.  Size (diameter times length) and location (3-D displacements) of each ablation zone induced by 527 sonications (with [n = 471] and without [n = 56] feedback) were analyzed according to the thermal dose obtained with MR thermometry.  Prospectively defined acceptance ranges of targeting accuracy were ± 5 mm in left-right (LR) and cranio-caudal (CC) directions and ± 12 mm in antero-posterior (AP) direction.  Effects of feedback control in 8- and 12-mm treatment cells were evaluated by using a mixed model with repeated observations within patients.  Overall mean sizes of ablation zones produced by 4-, 8-, 12-, and 16-mm treatment cells (with and without feedback) were 4.6 mm ± 1.4 (standard deviation) × 4.4 mm ± 4.8 (n = 13), 8.9 mm ± 1.9 × 20.2 mm ± 6.5 (n = 248), 13.0 mm ± 1.2 × 29.1 mm ± 5.6 (n = 234), and 18.1 mm ± 1.4 × 38.2 mm ± 7.6 (n = 32), respectively.  Targeting accuracy values (displacements in absolute values) were 0.9 mm ± 0.7, 1.2 mm ± 0.9, and 2.8 mm ± 2.2 in LR, CC, and AP directions, respectively.  Of 527 sonications, 99.8 % (526 of 527) were within acceptance ranges.  Feedback control had no statistically significant effect on targeting accuracy or ablation zone size.  However, variations in ablation zone size were smaller in the feedback control group.  The authors concluded that sonication accuracy of volumetric MRI-guided HIFU ablation of uterine fibroids appears clinically acceptable and may be further improved by feedback control to produce more consistent ablation zones.

Brkljacic et al (2013) noted that breast cancer is a common malignancy causing high mortality in women especially in developed countries.  Due to the contribution of mammographic screening and improvements in therapy, the mortality rate from breast cancer has decreased considerably.  An imaging-based early detection of breast cancer improves the treatment outcome.  Mammography is generally established not only as diagnostic but also as screening tool, while breast ultrasound plays a major role in the diagnostic setting in distinguishing solid lesions from cysts and in guiding tissue sampling.  Several indications are established for contrast-enhanced MRI.  Thermography was not validated as a screening tool and the only study performed long ago for evaluating this technology in the screening setting demonstrated very poor results.  The conclusion that thermography might be feasible for screening cannot be derived from studies with small sample size, unclear selection of patients, and in which mammography and thermography were not blindly compared as screening modalities.  Thermography cannot be used to aspirate, biopsy or localize lesions pre-operatively since no method so far was described to accurately transpose the thermographic location of the lesion to the mammogram or ultrasound and to surgical specimen.  The authors concluded that thermography cannot be proclaimed as a screening method, without any evidence whatsoever.

The Work Loss Data Institute’s guideline on “Low back -- lumbar & thoracic (acute & chronic)” (2013) listed thermography (infrared stress thermography) as one of the interventions/procedures that was considered, but is not recommended.

Sanchis-Sanchez et al (2014) noted that musculoskeletal injuries occur frequently.  Diagnostic tests using ionizing radiation can lead to problems for patients, and infra-red thermal imaging could be useful when diagnosing these injuries.  A systematic review was performed to determine the diagnostic accuracy of infra-red thermal imaging in patients with musculoskeletal injuries.  A meta-analysis of 3 studies evaluating stress fractures was performed and found a lack of support for the usefulness of infra-red thermal imaging (including thermography) in musculoskeletal injuries diagnosis.

Dibai-Filho and Guirro (2015) reviewed recent studies published on the use of infra-red thermography (IRT) for the assessment of myofascial trigger points (MTrPs).  A search of the MEDLINE, CINAHL, PEDro, and SciELO databases was carried out between November 2012 and January 2013 for articles published in English, Portuguese, or Spanish from the year 2000 to 2012.  Because of the nature of the included studies and the purpose of this review, the analysis of methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool.  The search retrieved 11 articles, 2 of which were excluded based on language (German and Chinese); 3 were duplicated in different databases, 1 did not use IRT for diagnostic purposes, and the other did not use IRT to measure the skin temperature.  Thus, the final sample was made up of 4 observational investigations: 3 comparative studies and 1 accuracy study.  The authors concluded that at present, there are few studies evaluating the accuracy and reliability of IRT for the diagnosis and assessment of MTrPs.  Of the few studies present, there is no agreement on skin temperature patterns in the presence of MTrPs.

Burke-smith et al (2015) states that currently the only evidence-based adjunct to clinical evaluation of burn depth is laser Doppler imaging (LDI), although preliminary studies of alternative imaging modalities with instant image acquisition are promising.  These researchers investigated the accuracy of IRT and spectrophotometric intracutaneous analysis (SIA) for burn depth assessment, and compared this to the current gold standard: LDI.  They included a comparison of the 3 modalities in terms of cost, reliability and usability.  These investigators recruited 20 patients with burns presenting to the Chelsea and Westminster Adult Burns Service.  Between 48 hours and 5 days after burn, these researchers recorded imaging using
  1. moorLDI2-BI-VR (LDI),
  2. FLIR E60 (IRT) and
  3. Scanoskin (SIA). 

Subsequent clinical management and outcome was as normal, and not affected by the extra images taken.  A total of 24 burn regions were grouped according to burn wound healing: group A healed within 14 days, group B within 14 to 21 days, and group C took more than 21 days or underwent grafting.  Both LDI and IRT accurately determined healing potential in groups A and C, but failed to distinguish between groups B and C (p > 0.05).  Scanoskin interpretation of SIA was 100 % consistent with clinical outcome.  The authors concluded that FLIR E60 and Scanoskin both presented advantages to moorLDI2-BI-VR in terms of cost, ease-of-use and acceptability to patients.  Infra-red thermography is unlikely to challenge LDI as the gold standard as it is subject to the systematic bias of evaporative cooling.  At present, the LDI color-coded palette is the easiest method for image interpretation, whereas Scanoskin monochrome color-palettes are more difficult to interpret.  However the additional analyses of pigment available using SIA may help more accurately indicate the depth of burn compared with perfusion alone.  The authors suggested development of Scanoskin software to include a simplified color-palette similar to LDI and additional work to further investigate the potential of SIA as an alternative to the current gold standard.

Evaluation of Burn Wounds

Prindeze and associates (2015) noted that despite advances in perfusion imaging, burn wound imaging technology continues to lag behind that of other fields.  Quantification of blood flow is able to predict time for healing, but clear assessment of burn depth is still questionable.  Active dynamic thermography (ADT) is a non-contact imaging modality capable of distinguishing tissue of different thermal conductivities.  Utilizing the abnormal heat transfer properties of the burn zones, these researchers examined if ADT was useful in the determination of burn depth in a model of early burn wound evaluation.  Duroc pigs (castrated male; n = 3) were anesthetized, and 2 burns were created with an aluminum billet at 3 and 12 seconds.  These contact times resulted in superficial partial and deep partial thickness burn wounds, respectively.  Active dynamic thermography and laser Doppler imaging (LDI) imaging were performed every 30 minutes post-burn for a total of 5 imaging sessions ending 150 minutes post-burn.  For ADT, imaging excitation was performed for 42 to 120 seconds with dual quartz-infrared lamps, and subsequent infrared image capture was performed for 300 seconds; MATLAB-assisted image analysis was performed to determine burn zone region of interest thermal relaxation and characteristic patterns.  Laser Doppler imaging was performed with a moorLDI system, and biopsies were captured for histology following the 150-minute imaging session.  Both ADT and LDI imaging modalities were able to detect different physical properties at 30, 60, 90, 120, and 150 minutes post-burn with statistical significance (p < 0.05).  Resultant ADT cooling curves characterized greater differences with greater stimulation and a potentially more identifiable differential cooling characteristic.  Histological analysis confirmed burn depth.  The authors concluded that this preliminary work confirmed that ADT can measure burn depth and is deserving of further research either as a stand-alone imaging technology or in combination with a device to assess perfusion.

Burke-Smith and colleagues (2015) stated that the only evidence-based adjunct to clinical evaluation of burn depth is LDI, although preliminary studies of alternative imaging modalities with instant image acquisition are promising.  These investigators examined the accuracy of IRT and spectrophotometric intracutaneous analysis (SIA) for burn depth assessment, and compared this to the current gold standard: LDI.  They included a comparison of the 3 modalities in terms of cost, reliability and usability.  These investigators recruited 20 patients with burns presenting to the Chelsea and Westminster Adult Burns Service.  Between 48 hours and 5 days post-burn, these researchers recorded imaging using moorLDI2-BI-VR (LDI), FLIR E60 (IRT) and Scanoskin (SIA).  Subsequent clinical management and outcome was as normal, and not affected by the extra images taken.  A total of 24 burn regions were grouped according to burn wound healing: group A healed within 14 days, group B within 14 to 21 days, and group C took more than 21 days or underwent grafting.  Both LDI and IRT accurately determined healing potential in groups A and C, but failed to distinguish between groups B and C (p > 0.05).  Scanoskin interpretation of SIA was 100 % consistent with clinical outcome.  The authors concluded that FLIR E60 and Scanoskin both presented advantages to moorLDI2-BI-VR in terms of cost, ease-of-use and acceptability to patients.  Infrared thermography is unlikely to challenge LDI as the gold standard as it is subject to the systematic bias of evaporative cooling.  At present, the LDI color-coded palette is the easiest method for image interpretation, whereas Scanoskin monochrome color-palettes are more difficult to interpret.  However the additional analyses of pigment available using SIA may help more accurately indicate the depth of burn compared with perfusion alone.  The authors suggested development of Scanoskin software to include a simplified color-palette similar to LDI, and additional work to further investigate the potential of SIA as an alternative to the current gold standard.

Evaluation of Dry Eye Disease

Tan and colleagues (2016) evaluated the effectiveness of IR ocular thermography in screening for dry eye disease (DED); IR ocular thermography was performed on 62 dry eye and 63 age- and sex-matched control subjects.  Marking of ocular surface and temperature acquisition was done using a novel “diamond” demarcation method.  A total of 30 static- and 30 dynamic-metrics were studied and receiver operating characteristic curves were plotted.  Effectiveness of the temperature metrics in detecting DED were evaluated singly and in combination in terms of their area under the curve (AUC), Youden's index and discrimination power (DP).  Absolute temperature of the extreme nasal conjunctiva 5s and 10s after eye opening were best detectors for DED.  With threshold value for the first metric set at 34.7° C, sensitivity and specificity was 87.1 % (95 % CI: 76.2 to 94.3 %) and 50.8 % (95 % CI: 37.9 to 63.6 %), respectively.  With threshold value for the second metric set at 34.5°C, sensitivity and specificity was 77.6 % (95 % CI: 64.7 to 87.5 %) and 61.9 % (95 % CI: 48.8 to 73.9 %), respectively.  The 2 metrics had moderate accuracy and limited performances with AUC of 72 % (95 % CI: 63 to 81 %) and 73 % (95 % CI: 64 to 82 %); Youden index of about 0.4 and DP of 1.07 and 1.05, respectively.  None of the dynamic metrics was good detector for DED.  Combining metrics was not able to increase the AUC.  The authors concluded that the findings of this study suggested some utility for the application of IR ocular thermography for evaluation of patients with DED.

Evaluation of Leprosy

Cavalheiro and associates (2016) examined if IRT would be able to measure the change in temperature in the hands of people with leprosy.  The study assessed 17 leprosy patients who were under treatment at the National Reference Center for Sanitary Dermatology and Leprosy, and 15 people without leprosy for the control group.  The infrared camera FLIR A325 and Therma CAM Researcher Professional 2.9 software were used to measure the temperature.  The room was air-conditioned, maintaining the temperature at 25° C; the distance between the camera and the limb was 70 cm.  The vasomotor reflex of patients was tested by a cold stress on the palm.  The study showed a significant interaction between the clinical form of leprosy and temperature, where the control group and the borderline-borderline form revealed a higher initial temperature, while borderline-lepromatous and lepromatous leprosy showed a lower temperature.  Regarding vasomotor reflex, lepromatous leprosy patients were unable to recover the initial temperature after cold stress, while those with the borderline-tuberculoid form not only recovered but exceeded the initial temperature.  The authors concluded that IRT proved a potential tool to assist in the early detection of neuropathies, helping in the prevention of major nerve damage and the installation of deformities and disabilities that are characteristic of leprosy.

Management of Infantile Hemangioma

In a preliminary, prospective, observational study, Burkes et al (2016) applied a functional imaging method, dynamic IRT, to investigate infantile hemangiomas (IH) status versus control skin and over time.  A total of 25 subjects with superficial or mixed IHs (age of less than 19 months) over 59 clinic visits were included in this study.  Infrared images of IHs and control sites, standardized color images, and three-dimensional (3D) images were obtained.  Tissue responses following application and removal of a cold stress were recorded with video IRT.  Outcomes included areas under the curve during cooling (AUCcool ) and rewarming (AUCrw ) and thermal intensity distribution maps.  AUCcool and AUCrw were significantly higher and cooling rate slower for IHs versus uninvolved tissue indicating greater heat, presumably due to greater perfusion and metabolism for the IH.  Infra-red distribution maps showed specific areas of high and low temperature.  Significant changes in IH thermal activity were reflected in the difference (AUCcool - AUCrw ), with 6.2 at 2.2 months increasing to 37.6 at 12.8 months; IH cooling rate increased with age, indicating slower recovery, and interpreted as reduced proliferation and/or involution.  The authors concluded that dynamic IRT was a well-tolerated, quantitative functional imaging modality appropriate for the clinic, particularly when structural changes, i.e., height, volume, color, were not readily observed.  They stated that dynamic IRT may aid in monitoring progress, individualizing treatment, and evaluating therapies.

Monitoring of Diabetes Mellitus

Staffa et al (2016) stated that foot complications in persons with diabetes mellitus (DM) are associated with substantial costs and loss of quality of life.  Increasing evidence suggests changes in skin temperature, measured using an IRT system, may be a predictor of foot ulcer development in patients with DM.  In a case study, these researchers described the long-term IRT findings and overall clinical outcomes of a patient with DM and peripheral vascular disease (PVD).  Foot temperature measurements using IRT were obtained slightly more than 1 year before and immediately following endovascular treatment of a 76-year old man, a non-smoker with type 2 DM, hypertension, and ischemic heart disease with cardiac arrhythmia.  Although he was otherwise asymptomatic, the infrared measurement showed an average temperature difference of 2.3˚ C between the left and right foot until he developed a small, trauma-induced wound on the left foot, at which time left foot temperature increased.  He was diagnosed with recto-sigmoid adenocarcinoma, underwent surgery and chemotherapy, and subsequently was evaluated for PVD.  Before undergoing peripheral angiography and percutaneous transluminal angioplasty, IRT evaluation showed a hot spot on the left heel.  Immediately following endovascular treatment, the mean temperature difference between the right and left foot was low (0.2˚ C), but a Stage I pressure ulcer was visible on the left heel.  Skin breakdown in that area was observed 2 months later, and the wound continued to increase in size and depth.  The patient died shortly thereafter due to complications of cancer.  In this case study, a series of infrared images of foot skin temperatures appeared to show a relationship with blood circulation and wound/ulcer development and presentation.  The authors concluded that IRT has the ability to instantaneously measure the absolute temperature of the skin surface over a large area without direct skin contact.  However, they stated that these devices are very sensitive; and prospective clinical studies are needed to determine the validity, reliability, sensitivity, and specificity of these measurements for routine use in patients who are at risk for vascular disease and/or foot ulcers.

Predicting Pressure Ulcers

In a systematic review, Oliveira and colleagues (2017) examined the clinical significance of ultrasound (US), thermography, photography and sub-epidermal moisture (SEM) measurement in detecting skin/tissue damage and thus predicting the presence of pressure ulcers (PUs); determined the relative accuracy of one of these assessment methods over another; and made recommendations for practice pertaining to assessment of early skin/tissue damage.  The following databases, Cochrane Wounds Group Specialized Register, the Cochrane Central Register of Controlled Trials, Ovid Medline, Ovid Embase, Elsevier version, Ebsco CINAHL, ClinicalTrials.gov , WHO International Clinical Trials Registry (ICTR) and The EU Clinical Trials Register were searched for terms including; thermography, ultrasound, sub-epidermal moisture, photograph and pressure ulcer.  These investigators identified 4 SEM, 1 thermography and 5 ultrasound studies for inclusion in this review.  Data analysis indicated that photography was not a method that allowed for the early prediction of PU presence; SEM values increased with increasing tissue damage, with the sacrum and the heels being the most common anatomical locations for the development of erythema and stage I PUs.  Thermography identified temperature changes in tissues and skin that may give an indication of early PU development; however the data were not sufficiently robust; US detected pockets of fluid/edema at different levels of the skin that were comparable with tissue damage.  Thus, SEM and US were the best methods for allowing a more accurate assessment of early skin/tissue damage.  Using the EBL Critical Appraisal Tool, the validities of the studies varied between 33.3 to 55.6 %, meaning that there is potential for bias within all the included studies.  All of the studies were situated at level IV, V and VII of the evidence pyramid.  These researchers noted that although the methodological quality of the studies warrants consideration, these studies showed the potential that SEM and US have in early PU detection.  The authors concluded that SEM and US are promising in the detection and prediction of early tissue damage and PU presence.  However, they stated that these methods should be further studied to clarify their potential for use more widely in PU prevention strategies.

Determining the Efficacy of Stroke Rehabilitation

Hegedus (2018) stated that maintaining good physiological circulation in the extremities requires an optimally functioning muscle pump.  Stroke symptoms indicate a change in venous circulation.  In this study, these researchers measured changes in joint function and microcirculation, and the correlation between them.  A total of 16  randomly selected post-stroke patients with hemiparesis affecting mainly the upper extremities began undergoing rehabilitation 13 ± 4 days following stroke.  Thermograms were taken with a Fluke Ti 20 (Fluke Corporation, WA) pre-treatment and post-treatment, and a physiotherapy documentation form was completed.  Treatment comprised 15 physiotherapy, massage, and galvanic therapy sessions per patient, with the side exhibiting no neurological symptoms as a control.  Joint function showed significant improvement on the affected side (p < 0.05).  Thermographic examinations revealed microcirculatory dysfunction in the affected extremities in 100 % of the cases.  Following treatment, temperature increased significantly (p ≥ 0.5°C) on the affected side.  A strong correlation (r) was observed between joint function and temperature change (p < 0.05).  The authors concluded that thermography was shown to be a reliable method for monitoring the effects of stroke rehabilitation treatment.  They stated that thermographic testing may enable clinicians to predict the course of the trauma and the effectiveness of treatment even at the acute stage.

Thermography for Evaluating Acute Skin Toxicity of Breast Radiotherapy

Maillot and associates (2018) stated that radiotherapy is a common adjuvant treatment of breast cancer.  Acute radiation-induced dermatitis is a frequent side effect.  These researchers hypothesized whether it is possible to capture the increase of local temperature as a surrogate of the inflammatory state induced by radiotherapy.  They designed a prospective, observational, single-center study to acquire data on temperature rise in the treated breast during the course of radiotherapy, establish a possible association with the occurrence of dermatitis and examine the predictive value of temperature increase in future occurrences of radiation-induced dermatitis.  All patients presenting for neoadjuvant or adjuvant radiotherapy during the course of breast cancer treatment at the university hospital of Martinique were considered for inclusion.  Every week, patients were examined by 2 trained investigators for the occurrence of radiation-induced dermatitis, graded based on Radiotherapy Oncology Group, Common Terminology Criteria for Adverse Events v.4.0 and Wright scales.  A frontal thermal image of torso was taken in strictly controlled conditions, with a calibrated TE-Q1 camera (Thermal Expert, i3systems, Daejeon, Korea).  These investigators studied temperature differences between the irradiated breast or thoracic wall and the contralateral area.  For each thermal picture, these researchers measured the difference in maximum temperature as well as the difference in minimum temperature and the difference in the average temperature in the considered area.  They studied the evolution of these parameters over time (week after week), measuring the maximum recorded difference and its correlation to acute radiation dermatitis intensity.  A total of 64 consecutive patients were included.  For all patients, these investigators noticed an increase of temperature during the course of radiotherapy.  Difference in maximum, minimum and average temperature was higher between the 2 breasts of patients with a radiation-induced dermatitis grade 2 or above compared to patients with no or mild dermatitis.  Higher temperatures were also significantly associated with an increased sensation of discomfort, as recorded by questionnaire (p < 0.05).  The authors concluded that as expected from the inflammatory phenomena involved in radiation-induced dermatitis, a noticeable increase in temperature during the course of radiotherapy was observed in all patients.  Furthermore, high-grade radiation-induced dermatitis was strongly associated with an additional increase in local temperature, which was probably linked to the intense inflammatory reaction.  Lastly, with a 1.4°C threshold set beforehand, it was possible to anticipate the occurrence of radiation-induced dermatitis, with interesting positive and negative predictive values (PPV and NPV) of 70 % and 77 %, respectively in this  population.  Moreover, these researchers stated that these findings need to be confirmed in a dedicated study.

Thermography for Evaluating and Monitoring of Individuals Emery-Dreifuss Muscular Dystrophy

Cabizosu and colleagues (2018) noted that Emery-Dreifuss muscular dystrophy (EDMD) is a clinical condition characterized by neuro-skeletal and cardiac impairments.  By means of thermography, new insights could be obtained regarding the evaluation and follow-up of this disease.  Actually, musculoskeletal disorders are a major cause of counseling and access to rehabilitation services and are some of the most important problems that affect the quality of life of many people.  There are urgent clinical and research needs for the assessment and follow-up of patients with EDMD.  These researchers offered a new possible hypothesis of validating thermographic techniques that support the evaluation and clinical follow-up of the EDMD.  They relied on evidence of existing bibliography.  These investigators performed a systematic review; and after the application of an automatic and manual filter, inclusion and exclusion criteria, no study was obtained.  There is a lack of evidence on the use of thermography in EDMD.  Due to a lack of information, these researchers expanded the search to studies concerning the use of thermography in relation to alterations of the musculoskeletal system compatible with those of EDMD, genetic diseases related to the X chromosome and more generally muscular atrophy.  Based on other studies performed in diseases that showed signs and symptoms similar to EDMD, the authors believed that a new line of translational research could be opened with novel findings and they thought thermography could be an optimal tool for the clinical monitoring of this pathology.  These researchers believed that it would be of a great importance to carry out an observational study, to lay the foundations for future work, that relate thermography to EDMD.

Thermography for Joint Assessment in Individuals with Inflammatory Arthritis

Jones and associates (2018) noted that rheumatoid arthritis (RA) is a common inflammatory disease that causes destruction of joints.  Accurate recognition of active disease has significant implications in determining appropriate treatment; however, there is significant inter-rater variability in clinical joint assessment.  In a cross-sectional study, these researchers evaluated the use of thermographic imaging in the evaluation of inflammatory arthritis activity as an adjunct to clinical assessment.  This trial included 79 subjects recruited from the University of Alberta out-patient rheumatology clinic.  These investigators compared the hand joints of 49 patients with RA diagnosed by American College of Rheumatology (ACR) criteria to 30 healthy volunteers.  Convenience sampling of consecutive RA patients was undertaken.  The effect of clinical assessment (HAQ and DAS-28) on joint temperature was evaluated using a linear mixed effect model.  A thermography camera, FLIR T300 model, 30-Hz, was used to obtain both thermographic and digital images on subjects.  Pearson's correlation coefficient was used to assess the correlation of clinical assessments and average joint temperature averaged over all joints.  Thermographic analysis did not associate with clinical measures of disease activity.  In RA patients, there was no statistically significant relationship between joint temperature and clinical assessment of disease activity including Health Assessment Questionnaire (coefficient estimate - 0.54, p = 0.056), swollen joints (coefficient estimate - 0.09, p = 0.238), or serologic markers of inflammation such as C-reactive protein (CRP; coefficient estimate - 0.006, p = 0.602) and erythrocyte sedimentation rate (ESR; coefficient estimate - 0.01, p = 0.503).  The authors concluded that evaluation of disease activity requires a multi-faceted approach that includes clinical assessment and appropriate imaging.  They stated that there may be a role for thermography in assessment of larger joints; however, it does not appear to be an effective modality for the small joints of the hand.

Thermography for Pre- and Peri-Operative Management of Hidradenitis Suppurativa

Derruau and co-workers (2018) stated that hidradenitis suppurativa (HS) is a chronic, inflammatory, and recurrent skin disease.  Surgical excision of wounds appears to be the only curative treatment for the prevention of recurrence of moderate-to-severe stages; MRI is a standard reference examination for the detection of HS peri-anal inflammatory fistula.  In this case study, the use of real-time medical infrared thermography (MIT), in combination with MRI as appropriate imaging, was proposed.  The objective was to assist surgeons in the pre- and peri-surgical management of severe perianal HS with the intent to ensure that all diseased lesions were removed during surgery and therefore to limit recurrence.  The results showed that MIT, combined with MRI, could be a highly effective strategy to address thermally distinguished health tissues and inflammatory sites during excision, as characterized by differential increases in temperature.  Medical infrared thermography could be used to check the total excision of inflammatory lesions as a non-invasive method that is not painful, not radiant, and is easily transportable during surgery.  The authors concluded that this method could be complementary with MRI in providing clinicians with objective data on the status of tissues below the perianal skin surface in the pre- and peri-operating management of severe HS.  This was a single-case study; its findings need to be validated by well-designed studies.

Infrared Thermography for Diagnosis and Management of Vasculitis, Early Identification of Skin Neoplasms, Esophageal Monitoring, and Screening for Adolescent Idiopathic Scoliosis

Lin and colleagues (2018) noted that vasculitis is a clinical condition with associated diagnostic challenges due to non-specific symptoms and lack of a confirmatory imaging modality.  These investigators reported a case of a 39-year old woman who developed generalized malaise, lethargy, and headache.  Laboratory evaluation showed elevated inflammatory markers.  Conventional imaging studies including computed tomography (CT) and carotid duplex ultrasound (US) were unremarkable.  Infrared thermography revealed enhanced thermographic signals in the left carotid artery and aortic arch.  Corticosteroid therapy was commenced, and the patient responded well.  Follow-up infrared thermography at 6 months showed complete resolution of the thermographic pattern, and the patient remained symptom-free.  The authors concluded that this case highlighted the potential clinical utility of using infrared thermography in patients with vasculitis.  The enhanced thermal signals in the aortic arch and carotid artery provided valuable information in the diagnosis and treatment of arteritis in this patient.  This technology was similarly beneficial in subsequent surveillance evaluation once the patient completed the prescribed treatment.  Moreover, they stated that further studies are needed to determine the clinical sensitivity and diagnostic accuracy of this imaging modality in vasculitis.

Magalhaes and associates (2018) stated that infrared thermal imaging captures the infrared radiation emitted by the skin surface.  The thermograms contain valuable information, since the temperature distribution can be used to characterize physiological anomalies.  Thus, the use of infrared thermal imaging (IRT) has been studied as a possible tool to aid in the diagnosis of skin oncological lesions.  These researchers evaluated the current state of the applications of IRT in skin neoplasm identification and characterization.  They carried out a literature survey using the reference bibliographic databases: Scopus, PubMed and ISI Web of Science.  Keywords (thermography, infrared imaging, thermal imaging and skin cancer) were combined and its presence was verified at the title and abstract of the article or as a main topic.  Only articles published after 2013 were considered during this search.  A total of 55 articles were encountered, resulting in 14 publications for revision after applying the exclusion criteria.  It was denoted that IRT have been used to characterize and distinguish between malignant and benign neoplasms and different skin cancer types; IRT has also been successfully applied in the treatment evaluation of these types of lesions.  The authors concluded that trends and future challenges have been established to improve the application of IRT in this field, disclosing that dynamic infrared thermography is a promising tool for early identification of oncological skin conditions.

Daly and co-workers (2018) noted that catheter ablation for atrial fibrillation (AF) has potential to cause esophageal thermal injury.  Esophageal temperature monitoring during ablation is commonly used; however, it has not eliminated thermal injuries, possibly because conventional sensors have poor spatial sampling and response characteristics.  To enhance understanding of temperature dynamics that may underlie esophageal injury, these researchers tested a high-resolution, intra-body, infrared thermography catheter to continuously image esophageal temperatures during ablation.  Patients undergoing AF ablation were instrumented with a flexible, 9F infrared temperature catheter inserted nasally (n = 8) or orally (n = 8) into the esophagus adjacent to the left atrium.  Ablation was performed while the infrared catheter continuously recorded surface temperatures from 7,680 points/sec circumferentially over a 6-cm length of esophagus.  Physicians were blinded to temperature data.  Endoscopy was performed within 24 hours to document esophageal injury.  Thermal imaging showed that most patients (10/16) experienced greater than or equal to 1 events where peak esophageal temperature was over 40° C; 3 patients experienced temperatures over 50° C; and 1 experienced over 60 °C.  Analysis of temperature data for each subject's maximum thermal event revealed high gradients (2.3 ± 1.4° C/mm) and rates of change (1.5 ± 1.3° C/sec) with an average length of esophageal involvement of 11.0 ± 5.4 mm.  Endoscopy identified 3 distinct thermal lesions, all in patients with temperatures over 50° C; all resolved within 2 weeks.  The authors concluded that infrared thermography provided dynamic, high-resolution mapping of esophageal temperatures during cardiac ablation.  Esophageal thermal injury occurred with temperatures of over 50° C and was associated with large spatiotemporal gradients.  Moreover ,they stated that additional studies are needed to determine the relationships between thermal parameters and esophageal injury.

In an editorial that accompanied the afore-mentioned study by Daly et al (2018), Borne and Nguyen (2018) stated that “it is important to note the multiple limitations of esophageal temperature monitoring.  First, to be effective, esophageal monitoring must accurately reflect the esophageal temperature.  The esophagus is a broad and patulous structure, and the position of a temperature probe might not align with the ablation catheter such that monitoring might provide a false sense of security.  In a prior investigation in which 2 commercially available probes (9F esophageal probe and an 18F esophageal stethoscope) were used among patients undergoing ablation, there were significant differences in the peak temperature and rise in temperature between the probes, suggesting that significant temperature variation exists among frequently used temperature probes.  Second, there is evidence to suggest that the use of a temperature probe can be potentially harmful.  In an ex vivo model, ablation near a non-insulated multi-sensor esophageal probe significantly increased temperatures in the tissues adjacent to the ablation lesion compared with lesions without a nearby temperature probe.  This was echoed in clinical work in which patients undergoing AF ablation were enrolled prospectively to receive an esophageal temperature probe-guided ablation strategy versus no temperature monitoring …  The study has some notable limitations.  First, there is limited validation of this technology for esophageal temperature monitoring.  A previous report described the use of infrared probes to monitor esophageal temperatures in a swine model, which were significantly higher than conventional probes.  The current authors reported their experience with the first-in-human use of the IRTC in a patient undergoing PVI.  Rigorous ex vivo and in vivo experiments need to be performed, establishing best practices and limitations of this technology, including how distance and location of the IRTC and ablation catheter affect temperature readings, if interactions between radiofrequency ablation and the probe exist and correlations to multiple different conventional temperature probes.  Second, lesions identified on endoscopy were not correlated to specific ablation lesions and their characteristics (i.e., contact force, force-time integral).  To best define risk for esophageal injury and thereby allow for risk modification, ablation characteristics and IRTC esophageal temperatures need to be analyzed.  For instance, is the risk of esophageal injury related to a time-temperature phenomenon, is it a structural/anatomic phenomenon, or is it related other factors that result in visible injury in some but not other ablation lesions causing temperatures >50° C?  If lesions identified on endoscopy did not correlate to higher esophageal temperatures, it is hard to know how temperature monitoring would guide ablation … Although further work needs to be performed in establishing the use of infrared thermography, the authors should be commended on their work for developing a system that has the potential to provide useful temperature monitoring data to improve the safety of AF catheter ablation.  Although the question remains as to what the optimal approach to avoid esophageal injury is, this study provides evidence to suggest that more accurate esophageal temperature monitoring is possible.  Until then, we should remain on red alert for risks of esophageal injury, in order to keep catheter ablation safe”.

Kwok and colleagues (2017) stated that adolescent idiopathic scoliosis (AIS) is a multi-factorial, 3-D deformity of the spine and trunk.  School scoliosis screening (SSS) is recommended by researchers as a means of early detection of AIS to prevent its progression in school-aged children.  The traditional screening technique for AIS is the forward-bending test because it is simple, non-invasive and inexpensive.  Other tests, such as the use of Moiré topography, have reduced the high false referral rates.  These researchers examined the use of infrared (IR) thermography for screening purposes based on the findings of previous studies on the asymmetrical para-spinal muscle activity of scoliotic patients compared with non-scoliotic subjects; IR thermography was performed with an IR camera to determine the temperature differences in para-spinal muscle activity.  A statistical analysis showed that scoliotic subjects demonstrated a statistically significant difference between the left and right sides of the regions of interest.  This difference could be due to the higher IR emission of the convex side of the observed area, thereby creating a higher temperature distribution.  The authors concluded that the findings of this study suggested the feasibility of incorporating IR thermography as part of SSS.  Moreover, they stated that future studies could also consider a larger sample of both non-scoliotic and scoliotic subjects to further validate the findings.

Intraoperative Infra-Red Thermography in Surgery of Glioblastoma Multiforme

Naydenov and colleagues (2017) noted that IRT is a real-time non-contact diagnostic tool with a broad potential for neurosurgical applications.  These researchers described the intraoperative use of this technique in a single patient with newly diagnosed glioblastoma multiforme (GBM).  An 86-year old woman was admitted in the clinic with a 2-month history of slowly progressing left-sided paresis.  Neuroimaging studies demonstrated an irregular space-occupying process consistent with a malignant glioma in the right fronto-temporo-insular region.  An elective surgical intervention was performed by using 5-aminolevulinic acid fluorescence (BLUE 400, OPMI) and intraoperative IRT brain mapping (LWIR, 1.25 mRad IFOV, 0.05°C NETD).  After dura opening, the cerebral surface appeared inconspicuous.  However, IRT revealed a significantly colder area (Δt° 1.01°C), well corresponding to the cortical epicenter of the lesion.  The underlying tumor was partially excised and the histological result was GBM.  The authors concluded that intraoperative IRT appeared to be a useful technique for subcortical convexity brain tumor localization.  Moreover, they stated that further studies with a large number of patients are needed to prove the reliability of this method in GBM surgery.

Dynamic Infrared Blood Perfusion Imaging

Dynamic infrared blood perfusion imaging (DIRI) is a new infrared imaging technique that is intended to detect changes in blood flow in tissue and organs by sensing passively emitted infrared radiation from tissues.  Potential clinical applications of DIRI include: use as an adjunctive screening tool for breast cancer and other cancers; evaluation of response to cancer chemotherapy; monitoring response to therapy in diabetic peripheral vascular disease; identifying perforator vessels during pre-surgical planning; assessing post-operative perfusion of pedicle flaps following reconstructive surgery (i.e., of the breast); mapping of functional cortex in patients undergoing tumor surgery; and determining cardiac bypass graft patency and perfusion of the myocardium in cardiac surgery.  Agostini and colleagues (2009) stated that dynamic infrared imaging is a promising technique in breast oncology.  Currently available evidence, however, is limited to evaluations of DIRI's technical feasibility.  There is an absence of evidence of the impact of DIRI on health outcomes.  The BioScanIR System (OmniCorder Technologies, Inc., Bohemia, NY) is an example of a DIRI device that is commercially available.

Lohman et al (2015) stated that over the last decade, microsurgeons have used a greater variety of more complex flaps.  At the same time, microsurgeons have also become more interested in technology, such as indo-cyanine green (ICG) angiography, dynamic infra-red thermography (DIRT), and photo-spectrometry, for pre-operative planning and post-operative monitoring.  These technologies are now migrating into the operating room, and are used to optimize flap design and to identify areas of hypo-perfusion or problems with the anastomoses.  Although relatively more has been published about ICG angiography, information is generally lacking about the intra-operative role of these techniques.  A systematic analysis of articles discussing intra-operative ICG angiography, DIRT, and photo-spectrometry was performed to better define the sensitivity, specificity, expected outcomes, and potential complications associated with these techniques.  For intra-operative ICG angiography, the sensitivity was 90.9 % (95 % confidence interval [CI]: 77.5 to 100) and the accuracy was 98.6 % (95 % CI: 97.6 to 99.7).  The sensitivity of DIRT was 33 % (95 % CI: 11.3 to 64.6), the specificity was 100 % (95 % CI: 84.9 to 100), and the accuracy was 80 % (95 % CI: 71.2 to 89.7).  The sensitivity of intra-operative photo-spectrometry was 92 % (95 % CI: 72.4 to 98.6), the specificity was 100 % (95 % CI: 98.8 to 100), and the accuracy was also 100 % (95 % CI: 98.7 to 100).  The authors concluded that these technologies for intra-operative perfusion assessment have the potential to provide objective data that may improve decisions about flap design and the quality of microvascular anastomoses.  However, more work is needed to clearly document their value.

Just and colleagues (2016) investigated static IRT and DIRT for intra- and post-operative free-flap monitoring following oropharyngeal reconstruction.  A total of 16 patients with oropharyngeal reconstruction by free radial forearm flap were included in this prospective, clinical study. Prior ("intraop_pre") and following ("intraop_post") completion of the microvascular anastomoses, IRT was performed for intra-operative flap monitoring.  Further IR images were acquired 1 day ("postop_1") and 10 days ("postop_10") after surgery for post-operative flap monitoring.  Of the 16, 15 transferred free radial forearm flaps did not show any perfusion failure.  A significant decreasing mean temperature difference (∆T: temperature difference between the flap surface and the surrounding tissue in Kelvin) was measured at all investigation points in comparison with the temperature difference at "intraop_pre" (mean values on all patients: ∆T intraop_pre = -2.64 K; ∆T intraop_post = -1.22 K, p < 0.0015; ∆T postop_1 = -0.54 K, p < 0.0001; ∆T postop_10 = -0.58 K, p < 0.0001).  Intra-operative DIRT showed typical pattern of non-pathological rewarming due to re-established flap perfusion after completion of the microvascular anastomoses. The authors concluded that static and dynamic IRT is a promising, objective method for intra-operative and post-operative monitoring of free-flap reconstructions in head and neck surgery and to detect perfusion failure, before macroscopic changes in the tissue surface are obvious.  They noted that a lack of significant decrease of the temperature difference compared to surrounding tissue following completion of microvascular anastomoses and an atypical re-warming following a thermal challenge are suggestive of flap perfusion failure.

Dynamic Infrared Blood Perfusion Imaging (DIRI) for Assessment of Skin Blood Perfusion in Cranioplasty

Rathmann and colleagues (2018) noted that complications in wound healing after neurosurgical operations occur often due to scarred dehiscence with skin blood perfusion disturbance.  The standard imaging method for intra-operative skin perfusion assessment is the invasive indocyanine green video angiography (ICGA).  The non-invasive dynamic infrared thermography (DIRT) is a promising alternative modality that was evaluated by comparison with ICGA.  These researchers performed a proof-of-concept study for qualitative comparison of DIRT with the standard ICGA.  This trial was carried out in 2 parts: investigation of technical conditions for intra-operative use of DIRT for its comparison with ICGA, and visual and quantitative comparison of both modalities in 9 patients.  Time-temperature curves in DIRT and time-intensity curves in ICGA for defined regions of interest were analyzed.  New perfusion parameters were defined in DIRT and compared with the usual perfusion parameters in ICGA.  The visual observation of the image data in DIRT and ICGA showed that operation material, anatomical structures and skin perfusion were represented similarly in both modalities.  Although the analysis of the curves and perfusion parameter values showed differences between patients, no complications were observed clinically.  These differences were represented in DIRT and ICGA equivalently.  The authors concluded that DIRT has shown a great potential for intra-operative use, with several advantages over ICGA.  The technique is passive, contactless and non-invasive.  The practicability of the intra-operative recording of the same operation field section with ICGA and DIRT has been demonstrated.  These researchers stated that the promising results of this proof-of-concept provided a basis for a trial with a larger number of patients.



Table: CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":

CPT codes not covered for indications listed in the CPB:

93740 Temperature gradient studies

ICD-10 codes not covered for indications listed in the CPB (not all-inclusive):

A30.0 - A30.9 Leprosy [Hansen's disease]
B02.22 Postherpetic trigeminal neuralgia
B02.29 Other postherpetic nervous system involvement
C00.0 - C96.9 Malignant neoplasms
D18.00 - D18.09 Hemangioma and lymphangioma, any site
E08.3211 - E13.37x9 Diabetes mellitus
E10.51 - E10.59
E11.51 - E11.59
Diabetes mellitus with circulatory complications [Type 1 or 2]
G71.09 Other specified muscular dystrophies
G90.50 - G90.59 Complex regional pain syndrome
H04.121 - H04.129 Dry eye syndrome
I25.10 - I25.9 Coronary atherosclerosis
I73.9 Peripheral vascular disease, unspecified
I77.6 Arteritis, unspecified
L73.2 Hidradenitis suppurativa
L89.000 - L89.95 Pressure ulcer
M06.4 Inflammatory polyarthropathy
M79.601 - M79.609 Pain in limb
M84.421S - M84.429S
M84.431S - M84.439S
S42.209S - S42.496S
S49.001S - S49.199S
S52.001S - S52.92xS
S59.001S - S59.299S
S62.90xS - S62.92xS
Fracture of upper extremity, sequela
S52.501+ - S52.509+
S52.531+ - S52.539+
Fracture of radius [open or closed]
T20.00xA - T32.99 Burns
Y84.2 Radiological procedure and radiotherapy as the cause of abnormal reaction of the patient, or of later complication, without mention of misadventure at the time of the procedure
Z01.810 Encounter for preprocedural cardiovascular examination
Z01.818 Encounter for other preprocedural examination
Z01.89 Encounter for other specified special examinations [not covered for intra-operative and post-operative perfusion assessment]
Z12.0 - Z12.9 Encounter for screening for malignant neoplasms
Z13.89 Encounter for screening for other disorder
Z51.11 - Z51.12 Encounter for antineoplastic chemotherapy or immunotherapy
Z95.1 Presence of aortocoronary bypass graft

The above policy is based on the following references:

  1. U.S. Department of Health and Human Services (DHHS), Public Health Service, Office of Health Technology Assessment. Thermography for indications other than breast lesions. Health Technology Assessment Reports. DHHS Pub. No. PHS 89-3438. Washington, DC: DHHS; August 1989.
  2. So YT, Olney RK, Aminoff MJ. Evaluation of thermography in the diagnosis of selected entrapment neuropathies. Neurology. 1989;39:1-5.
  3. So YT, Minoff JF, Olney RK. The role of thermography in the evaluation of lumbosacral radiculopathy. Neurology. 1989;349:1154-1158.
  4. Harper CM, Low PA, Realey RD, et al. Utility of thermography in the diagnosis of lumbosacral radiculopathy. Neurology. 1991;41:1010-1014.
  5. American Academy of Neurology, Therapeutics and Technology Assessment Subcommittee. Thermography in neurologic practice. Assessment. Neurology. 1990;40:523-525.
  6. Ilowite NT, Walco GA, Pochaczevsky R. Assessment of pain in patients with juvenile rheumatoid arthritis: Relation between pain intensity and degree of joint inflammation. Ann Rheumatic Diseases. 1992;51(3):343-346.
  7. Ben-Eliyahu DJ. Infrared thermographic imaging in the detection of sympathetic dysfunction in patients with patellofemoral pain syndrome. J Manipulative Physiol Ther. 1992;15:164-170.
  8. Leclaire R, Esdaile JM, Jequier JC, et al. Diagnostic accuracy of techniques used in low back pain assessment. Thermography, triaxial dynamometry, spinoscopy, and clinical examination. Spine. 1996;21(11):1325-1330, discussion 1331.
  9. Devulder J, Dumoulin K, De Laat M, Rolly G. Infra-red thermographic evaluation of spinal cord electrostimulation in patients with chronic pain after failed back surgery. Br J Neurosurg. 1996;10(4):379-383.
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