Sunday, June 6, 2010

Breast thermography?

Isn't technology incredible? Especially when it works. My most recent remarkable medical technology moment occurred the other day when I had a digital infrared thermal imaging (DITI) test. DITI, or thermography, is a no contact, non-invasive screening tool. When I took the test all I had to do was stand in front of the scanner. There is no risk of radiation, no needles and no nuclear dyes.  Ladies, imagine no cold, glass plates clamping down on your sensitive body parts! A screening test with NO side effects.  Like I said, remarkable.

No side effects sounded great, but I wondered how does thermography work? From what I understand, we all radiate infra-red heat (think night vision goggles). Each of us has our own unique heat signature and usually these are fairly symmetrical. Symmetry is important in heat signatures, but more on that later.

Anyway, the thermography technician explained to me that as I stand in front of the scanner it converts the infrared heat radiating from my body into electrical impulses. As the image from Meditherm shows, these impulses are then computer mapped using different colors. A photo is taken of these colored heat patterns. This is called a thermogram. Each color on the thermogram indicates more or less heat coming off the body.

Of course, being the wondering type of person I am,  I questioned why I needed a thermogram when I've already had digital mammograms, a contrast MRI and a sonogram of my breasts. My doctor explained that a thermogram is about looking at physiology, which is the study of the function of the body's systems.  Whereas, a mammogram, MRI and sonogram are all about anatomy, which is the study of the body's physical structures. He went on to say that because of this they can be complementary tests. 

So what is significant about temperature imbalances in the body showing up on a thermogram?  Well, remember I mentioned that symmetry or balance of heat signatures in the body is important. My doctor explained that he compares the heat signatures from one breast with the other.  If an imbalance between them is noted he considers it a "thermal signal." A thermal signal may be the result of "increased vascularity". What's that? Well, it may indicate disease and in some cases cancer. According to the American Cancer Society (ACS), when cancer cells begin to grow they start out by using nearby blood vessels. But the tumor soon outgrows this blood supply and it begins angiogenesis - the growth of new blood vessels.  As a result, increased vascularity, or blood flow, occurs in the area of the tumor. This additional blood supply increases metabolic heat which shows up as a thermal signal on the thermogram.
Interestingly, "without new blood vessels, a tumor can't grow larger than about the size of a pin head (about 1 to 2 cubic millimeters)(ACS)." Cancerquest states that "a mammogram can detect tumors at very early stages, when they are around the size of a pencil eraser." So what about the period of growth between pin head and pencil eraser stage? This is where breast thermography is particularly useful. It has the potential to detect problems earlier than mammography and this allows for earlier intervention and treatment.

So you may be wondering, like I was, why thermography isn't offered as a standard screening tool for breast cancer? Why isn't it used in conjunction with mammography? Why doesn't my insurance company cover this test? I'll get into this in my next post.  


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