Study Analysis
Thermology: Standardized Analysis and Application
By 1971, the clinical experience with thermography in the hands of a few specialized investigators had been demonstrated effective and had become recognized by the US Dept. of Health, Education and Welfare (HEW, now HHS) as a diagnostic technique for breast oncology and restrictive vascular disease. By 1974, the very favorable results from some small trials prompted the inclusion of thermography into a large-scale study funded by the National Cancer Institute: the Breast Cancer Detection and Demonstration Project. Unfortunately, this study was seriously flawed by the lack of specifics and standardization of equipment, technique, analytic criteria and reporting. The resulting failure of this study was widely misinterpreted as a failure of breast thermography - an impression that was often promulgated by other imaging specialists with competitive and proprietary interests. Thermography languished in the United States for more than twenty (20) years but was effectively developed in Europe and East Asia with large-scale studies. In 1975, the results of large-scale studies at the prestigious Pasteur University in Marseille, France, established an objective analytic system. This system has been refined by enhanced knowledge of basic science and increased clinical experience but remains the basis for breast thermology (the diagnostic science of infrared imaging) to this day.
The first classification category in the Marseille system defines a normal thermal profile of the breasts that is devoid of any of the thermology signs or criteria associated with risk for malignant breast disease. All thermal features demonstrate normal and adaptive response to the autonomic challenge. Normal contours are discerned and no significantly hyperthermic focal or vascular features are presented. Some patients will demonstrate distinct and significantly hypothermic patterns that are frequently associated with established cysts and/or fibro-adenomas. This will modify the classification as a TH1F. Annual comparative restudy is recommended.
The second category in the Marseille system defines a thermal profile of the breasts that features symmetrical, non-complex and moderately hyperthermic vascular patterns. All thermal features demonstrate normal and adaptive response to the autonomic challenge. The TH2 score indicates no thermal signs or criteria for malignant breast disease. However, while very unlikely, it is possible that some small malignant tumors may be in a quiescent state and their vascular development could be minimal. In this event, the very minor thermal characteristics may evade discernment, especially in an initial study. This thermology category is frequently associated with benign changes, such as glandular hyperplasia and the development of cysts and fibroadenomas. This will modify the classification as TH2F. Annual comparative thermology restudy is recommended and more frequent restudy may be clinically indicated.
The third category of the Marseille system defines a single thermology sign and indicates an atypical metabolic or vascular process. This may be based upon the discernment of an asymmetric and hyperthermic vascular or focal pattern, an asymmetric, diffuse and hyperthermic pattern involving a peri-areolar area or most of one breast, a discrete area in a vascular pattern that does not attenuate from the challenge procedure or an asymmetric physical distortion with local hyperthermia. This atypical category is associated with a minor or equivocal (<10-20%) risk of confirming malignant breast disease. It is likely that these atypical thermal features represent benign changes such as inflammation, acute cysts and/or fibroadenoma development, infection or personal variant, especially in an initial study. A thermology restudy in 60 to 90 days usually provides a differentiation. Clinical correlation is indicated for an association with a mass or abnormal skin changes that would have an additive effect on the overall risk for malignant disease. Strong familial or personal risk factors for breast cancer and are also additive. Other objective means of evaluating the breasts may be indicated. Experience demonstrates a targeted ultrasound as the most effective means of following-up on atypical or abnormal breast thermology. Blood markers such as CA15-3, CA125 and creatin-kinase-BB may be useful and mammography and ductal lavage may be indicated.
The post-surgical woman receives a special modifier "M", designating Mastectomy or "L", designating Lumpectomy. These are frequently used with the third category of the Marseille system on an initial study when any atypical thermal features are evident. The surgical procedures, radiation treatments and chemotherapy typically produce significant tissue inflammation, edema, abnormal tissue metabolism, nerve damage and revascularization that will likely impede the normal regulation of blood flow in the breast and results in artifact of the thermal patterns. These forms of artifact limit the value of thermology for approximately three months post-procedural when their influence usually has abated. Thermology can be a very useful means of monitoring the post-surgical woman for indications of persistent or recurrent malignant disease, especially in the axillary or sternal regions. The initial study may be of limited value and its best value obtained as a baseline for comparative restudy.
The fourth category in the Marseille system defines two or more thermology signs or a single thermology criterion. This must be considered a positive thermogram and represents a significant (65-85%) risk for malignant breast disease. Benign processes and personal variant are possible but unlikely as a basis for this abnormal classification, especially on an initial study. A clinical correlation is indicated for regional masses or abnormal skin changes and all available means of objective evaluation are indicated. However, it must be considered that a positive thermogram may precede positive results from other objective testing by 5-8 years. Thermology restudy in 60-90 days should be an important part of a comprehensive testing panel.
The fifth category in the Marseille system defines two or more thermology criteria. This category indicates a very high (approx. 96%) probability of confirming malignant breast disease. Benign processes or personal variant are very unlikely. A clinical correlation is indicated for regional masses and abnormal skin changes. Clearly, a patient with such a score is indicated for a comprehensive panel of objective evaluation with all possible alacrity. A thermology restudy in 60-90 days should be a part of this evaluation if these other methods do not demonstrate malignant breast disease, as thermology may precede other abnormal features by 5-8 years. neo-angiogenic blood vessels must be developed early in the life of a solid malignant tumor, certainly by three (3) mm in diameter, the practical limit of diffusion and into dense convoluted networks. During the late 1980's a group of anatomist from the University of Essen in Germany demonstrate the primitive lacunae structure of the neo-angiogenic vessels and their lack of a regular endothelial layer and complete lack of vascular smooth muscle. This meant neo-angiogenic vessels could not respond to the physiologic modulation by the autonomic nerve system, vasodilators or constrictors. The thermal energy manifest in infrared imagery of the body is a direct manifestation of the inherent inefficiencies of metabolism and the effect of circulating blood. Certainly, infrared energy is emitted superficially and certainly is strongly affected by skin perfusion but the characteristic high-energy vascular-like features associated with breast oncology are not frequently superficial. The question arises as to the mechanism responsible for the infrared vascular-like 'signatures' associated with breast oncology. An answer to this question came from the ability of infrared imagers in planetary orbit to assess subterranean features. Plainly put, if there is a suitable gradient to dissipate the superficial thermal energy, such as cool ambient air; high-energy thermal features from deep will 'float' to the surface by conduction. A higher gradient will facilitate the infrared 'signatures' of deeper high thermal energy especially through a relatively homogenous media. In medicine this effect is limited by ambient air sufficiently cold to causing shivering and the paradoxical hunting phenomenon of Lewis. Further, non-homogenous tissue will dissipate emerging thermal energy and obscure its detail. Fortuitously, human skin, irrespective of its pigmentation, emits infrared energy in essentially perfect proportion to its temperature and the human female breast is relatively homogenous tissue. Conversely, infrared imagery has found little use in the study of deep visceral organs that may be encapsulated, surrounded by heterogeneous tissues and approximated by large-caliber blood vessels.
To date, the development of thermal imaging technology has been directed to its industrial and engineering applications. Infrared imaging has applications that range from dynamic evaluation of tire stress-related failure to astronomy and its practical value has given impetus to a rapid succession of powerful features. The instruments of the 1950's were as stone knives and bear claws to the instruments available today. The first to the fourth generation thermographs were bulky, slow, cranky complex mechanical-optical analog scanning instruments with poor spatial resolute that recorded to photographic film or videotape. These early thermographs did not lend themselves to a quantitative means of analysis and were often little more than extensions of human vision. However, the fifth generation instruments originated in the mid-1990's and feature a dynamic interfaced with a modern digital computer. These instruments are frequently indium antimony focal plane or standing arrays with approximately seventy-five thousand individual detectors and few or no moving parts. The best of the current generation thermographs are twelve (12) to twenty-four (24) bit digital radiometric live images with an instantaneous field of view of better than sixty (60) micro-radians and a spatial resolution better than twenty 20 milliKelvin (20 mK). These images are recorded by a modern microcomputer (PC) as digital data, preserving the radiometric values of each detector pixel.
Medicine has been a qualitative sanctuary in an increasing quantitative world. Despite the perceptions of voluminous numbers as measures in units of millimeters of mercury or milligrams per deciliter, Medicine rarely integrates this data in any quantitative means of analysis for diagnosis or treatment. Perhaps it is that students with a predilection for number concepts gravitate towards computer science, engineering or mathematics rather than Medicine. It is an irony of our age that the marketing of corn flakes incorporates more quantitative and statistical analysis than the diagnosis or treatment of heart disease. This is not to denigrate the accomplishments of physicians as often they develop remarkable judgments. However, this is frequently due to detailed training and vast experiences that program their personal organic albeit qualitative reasoning devices. Harold Issard was able to achieve a consistent eighty-eight (88%) percent sensitivity in diagnosing early breast malignancy using simple infrared images with only the use of his experienced eye; educated by the integrated results of forty years of clinical experience. Currently in the World there are but a handful of thermologists with sufficient training and vast experience to qualify as 'expert readers' of breast infrared images. A majority of them do not employ any quantitative means of analysis. Instead they rely on pattern recognition alone to judge an abnormal patient study. There is a general agreement among the 'expert readers' on diagnostic indicators from breast infrared images and a reporting method based upon the Marseilles system. Some of them have objective criteria they employ while others rely strictly on subjective albeit experienced judgment.