Also called: Infrared Thermography
Mark Oren, M.D., FACP
Thermography is a test that measures the heat coming from the body. It has been approved by the U.S. Food and Drug Administration (FDA) to help detect breast cancer and other diseases, although its effectiveness has been the subject of debate.
Thermography is typically performed in an outpatient clinic by a board certified clinical thermographer who received specialized training and licensure in the practice.
Thermography typically uses two technologies: a highly sensitive infrared camera and a computer. The camera detects changes in the surface temperature of the breast. These changes may indicate the presence of precancerous cells or cancerous cells in their early stages of development. Information about temperature changes in the breast is relayed to a computer, which analyzes the information and creates an image (called a thermogram) that shows warmer areas in red and cooler areas (indicating normal breast tissue) in blue.
Proponents of thermography contend that it can detect cancers of the breast months or years earlier than traditional techniques such as mammography or physical examination. In addition, thermography usually does not involve physical contact with the breast and does not expose the patient to potentially harmful radiation.
However, many experts – including the American Cancer Society (ACS) – have expressed reservations about the effectiveness of thermography as a diagnostic tool for breast cancer. For now, most experts agree that thermography should only be used as an adjunct to other traditional techniques used to diagnose breast cancer.
Thermography is a tool for identifying breast cancer that uses super-sensitive infrared cameras and computer technology to detect heat on the surface of a patient’s breast. The presence of such heat is sometimes the result of intensive chemical and blood vessel activity that is characteristic of precancerous or cancerous tissue.
Although some health professionals support the use of thermography (also known as digital infrared imaging), organizations such as the American Cancer Society (ACS) maintain that there is no proof that this procedure is effective in detecting breast cancer in its early stages. In addition, it may not detect small cancers or tumors deeper in the breast and it cannot pinpoint the location of a tumor.
Two factors cause cancerous cells to generate heat that theoretically can be detected during thermography:
- Higher metabolic activity of cancer tissue compared to normal tissue. Cancer cells have higher rates of metabolism (physical and chemical processes in the body) than normal tissues. This higher metabolism registers as an increase in the surface temperature of the breast near the cancerous tissue. This is detected by the infrared camera.
- Angiogenesis. A cancerous tumor produces a chemical that promotes the development of blood vessels that supply the tumor with the nutrients it needs to keep growing. In addition, the cancer causes normal blood vessels to dilate (open) to provide even more blood to the forming tumor. Both of these activities produce additional heat which may be detected by the infrared camera.
The infrared camera used during thermography converts infrared radiation emitted from the skin into electrical impulses and feeds the information into a computer. The computer analyzes the temperature and vascular (blood vessel) changes and produces high-resolution images known as thermograms. These images can be displayed on a monitor for analysis, with areas of raised temperature appearing red and areas of normal temperature appearing blue. They can also be printed or sent to another physician electronically.
Thermography has been tested and researched since the 1950s. It originally involved the use of contact plates that measured the heat emitting from the breasts, although thermograms are now produced digitally. In 1982, the U.S. Food and Drug Administration (FDA) approved the use of thermography to help detect breast cancer and some circulation disorders, such as deep vein thrombosis and conditions relating to blood flow in the head and neck.
Proponents of thermography claim that the technique can detect signs of precancerous or cancerous cells far earlier than other imaging techniques. For example, mammography technology cannot detect cancer until a tumor has actually begun to form, which may take several years. Thermography is designed to detect the formation of new blood vessels and chemical changes that occur very early in a tumor’s development. Some experts contend that thermography can identify signs of the formation of breast cancer up to 10 years before any other technique can detect them.
In addition, thermography is touted as having certain advantages over traditional mammography procedures. During thermography, the machine does not touch the breast, in contrast to the squeezing of the breast that occurs during mammography. In addition, patients are not exposed to the potentially harmful radiation used in mammography.
However, many experts have expressed doubts about the effectiveness of thermography in diagnosing breast cancer. For example, the American Cancer Society (ACS) maintains that thermography is not a reliable diagnostic tool because it misses some cancers and has a high rate of false positives. The ACS warns that thermography should never be used as a replacement for mammograms.
Other experts have also criticized thermography for producing too many false results, and have argued that the technique cannot detect the heat of cancers located deep in the breast or under fatty areas. It has also been noted that not all cancers emit heat, and thus would not be revealed by a thermogram.
Still, some experts support thermography as a valuable tool in detecting breast cancers. Experts generally agree that thermography should not be used as a stand-alone diagnostic tool, but rather should be used with other diagnostic tools, such as mammograms, ultrasounds and physical examinations.
At present, new versions of thermography are being developed that may be more sensitive in detecting small temperature changes. These new forms of thermography may be more accurate than the versions used today.
The FDA has also approved the use of thermography to detect the following:
- Extracranial vessel disease (affecting the blood vessels in the head and neck)
- Neuromusculoskeletal disorders
- Vascular disease of the lower extremities