1. Aetna considers thermography (temperature gradient studies) experimental and investigational because available medical literature indicates thermography to be an ineffective diagnostic technique.

2. Aetna considers dynamic infrared perfusion imaging (DIRI) experimental and investigational because of a lack of evidence of its clinical utility.

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.

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.

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."

Currently, there is insufficient evidence to support the use of thermography for the diagnosis of complex regional pain syndrome. The use of thermography in the diagnosis of complex regional pain syndrome 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 three 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 92% 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.

Madjid and colleagues (2006) stated that up to two-thirds 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.

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.

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. 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.