What is Digital Infrared Imaging?

History of Thermography
Thermography, in medicine, is the graphic measurement of temperature patterns (or infrared radiation) from the human body, for the purpose of analysis. Our skin breathes via a constant exchange of gasses and heat form our environment. Infrared radiation, thus, refers to the emitting of heat away from the skin. This unconscious process of letting heat in and out through the opening and closing of the blood vessels is called of thermoregulation, and is controlled by the sympathetic division of our autonomic nervous system. 

Thermography's first use in medicine was rendered by Hippocrates, in about 480 B.C. He was able to gain information about disease by covering regions of the body in question with a mud slurry. The hotter areas dried first, therefore indicating pathology of the underlying organs.

	Hippocrates wrote, "In whatever part of the body excess of heat or cold is felt, disease is there to be discovered (1)."

DII or thermography was first used to investigate breast cancer in 1957 by Raymond Lawson, M.D., a surgeon and tumor metabolism researcher. Since then, there have been over 800 peer-reviewed studies in medical literature, studying over 300,000 women. In 1982, the FDA approved thermography as a breast screening procedure. Over the past thirty years, there have been large scale studies supporting its effectiveness, as well as the development of strict, standardized interpretation protocols, and great technological advancements in imaging hardware and computer processing.

Thermography Applications
DII requires the use of a highly sensitive camera to accurately measure heat from the surfaces of the breasts,  detecting temperature differences of .05 degree centigrade. DII is non-invasive, does not require radiation, breast compression, or intravenous injection, and is in no way harmful to the patient. In a carefully monitored temperature controlled room (between 18 and 23 degrees centigrade), blood vessels of normal tissue constrict to conserve heat. Thus,  DII can detect benign tumors, simple cysts, fibrocysts, infections, and other benign conditions.

	DII produces high resolution, diagnostic images of these minute temperature variations, which may signal a pre-cancerous state and/or the early signs of breast cancer, not able to be detected by physical examination or mammography (2,3,4,5,8).

DII can also be the first indicator that a cancerous situation  is developing (5). This is especially important since it takes approximately 8 to 10 years for a tumor to grow to be the size of a dime. In the early stages of tumor formation, the dilation of existing blood vessels and the formation of new blood vessels, or neoangiogenesis, along with chemical changes,  almost always increase the temperature of the surrounding breast tissue. Blood vessels supplying malignant tissue do not constrict,  due to fact that these vessels do not have walls of smooth muscle and their own sympathetic nervous system. In other words, tumor vasculature can not regulate its own heat loss; thus the vessels remain dilated in a constant temperature environment. The infrared camera  measures the heat patterns caused by this abnormal activity.  

When digitally produced and interpreted by qualified doctors, these abnormalities or changes in subsequent infrared images provide invaluable information. This is particularly true in patients with dense breasts, non-specific physical or mammographic findings, or women with a previous history of breast surgery or radiation. Interpretation of DII is not hindered by situations in which women are on hormone replacement therapy, pregnant, nursing, have fibrocystic, large, dense, or enhanced breasts.  Infrared imaging can therefore focus on areas that require further evaluation or close monitoring. 

	Studies show up to a 61% increase in survival rate when breast thermography and mammography are used together (5).

This information can then be used to direct further examinations and tests such as mammography, ultrasound, and/or MRI. Since DII is not an anatomical test,  it does not have the ability to pinpoint the location of the tumor. Thus, DII and mammography, do not replace, but compliment each other. The combined use of thermography, as well as mammography, physical exams, and properly executed self-exams, provide us with the earliest detection to date (2,3,5,8).

	Each patient has a unique infrared map of their breasts, that remains constant over years, unless there is a change in an underlying condition.

Any alteration of this thermal map can reflect an early sign of an abnormality. In patients without cancer, the imaging results are used to indicate the level of possible future cancer risk (6,7). As mentioned previously, an abnormal infrared image is the single most important marker for developing breast cancer, 10 times more significant than a family history of the disease (7). Depending upon the level of risk, re-examinations are performed at appropriate intervals to monitor the health of the breasts. This gives a woman time to decrease as many known risk factors as possible and initiate anti-carcinogenic lifestyle modifications. 

	Recent data suggests that DII may also help monitor the effects of some of the currently proposed anti-angiogenic treatments - currently recognized as a promising treatment strategy (2,4).

As with other types of imaging, sophisticated technology and expertise in obtaining the images are vital to interpret the findings. Although DII has an 90% accuracy rate, not all tumors are associated with a high degree of blood vessel activity, thus escaping detection. Tumors of this type tend to grow at a much slower rate and are less aggressive.  In these select cases, DII can be used as a prognostic indicator, suggesting a much better overall prognosis.

Since both physical and mammographic examination cannot detect all cancers, particularly smaller tumors in younger patients and those with dense breast tissue, efforts are currently directed at adjunctive screening procedures. Techniques such as MRI, doppler ultrasound, and scintimammography, are designed to be used in selected cases where physical and mammographic examinations have already picked up an abnormality. These tests also do not address the limitations of combined physical examination and mammography as frontline detection. Consequently,  too many patients who have undergone both screening tests have undetected breast cancer. Therefore, experts have concluded that no one procedure or method of imaging is solely adequate for breast cancer screening (1,4,9).

1. Adams, F. The Genuine Works Of Hippocrates. Baltimore: Williams and Wilkins, 1939.
2. Ahlgren P., M.D. et al." Is it Time to Reassess the Value of Infrared Breast Imaging?" Primary Care & Cancer (NCI) 18.2 (1998).
3. Belliveau N., M.D., et al. "Infrared Imaging of the Breast: Initial Reappraisal Using High-Resolution Digital Technology in 100 Successive Cases of Stage I  and II Breast Cancer." The Breast Journal 4. 4 (1998).
4. Gamigami P., M.D. Atlas of Mammography: New Early Signs in Breast Cancer. Blackwell Science, 1996.
5. Gautherie M., Ph.D. "Thermobiological Assessment of Benign and Malignant Breast Diseases." Am. J. Obstet. Gynecol. 147.8 (1983): 861-869.
6. Gros C., M.D., M. Gautherie, Ph.D. "Breast Thermography and Cancer Risk Prediction." Cancer 45.1 (1980): 51-56.
7. Haehnel P., M.D., et al. "Long-Term Assessment of Breast Cancer Risk by Thermal Imaging." Biomedical Thermology (1980): 279-301.
8. Keyserlingk J., M.D. "Time to Reassess the Value of Infrared Breast Imaging?" Oncology News Int. 6.9 (1997).
9. Nyirjesy I., M.D. et al. "Clinical Evaluation, Mammography and Thermography in the Diagnosis of Breast Carcinoma." Thermology 1 (1986): 170-173.