Breast Cancer on the Run in October: (Day 28) Breast MRI


Cancer is clever. A cancer cell will emerge and then start to develop its own blood supply to sustain itself. The vessels that it develops are generally immature and don’t regulate blood flow in and out of a structure in the same way as normal vessels.

img_1650It is this principle that is exploited by breast MRI. A contrast agent is given through a vein and it passes through the vasculature of the breast. Watching this contrast agent as it traverses the breast will lead one to conclude if the vessels are normal or whether they are cancer related by looking at enhancement patterns.

Breast MRI will provide a picture in three dimensions of a mass or a nodule, revealing what is on the surface and what is inside. Mammography and sonography are generally two dimensional studies looking at three dimensional objects.

No radiation is involved with MRI, unlike mammography. The technique exploits magnet and radio waves and alters the natural alignment of hydrogen atoms. The physics of this is complicated, but the images show on a computer screen and can then be digitally manipulated for further viewing.

Breast MRI is a more elaborate and expensive test that is becoming more popular and is coming down in price. Like all radiological studies for the breast, it has it good points and its bad points. It is useful for women with dense breasts, implants, and cancer. It does not do well with calcifications which are so important in mammography.

Which brings us to the rationale for all the testing we do to detect breast cancer. Mammography and sonography are the main cornerstones, but each of these tests has weaknesses or gaps in their ability to detect breast problems. So they complement each other, trying to address and overcome the weaknesses of the other.

We can now add MRI to the mix, although it is not used as widely for screening. MRI will detect cancers at a higher rate, again covering for weaknesses in mammography and sonography.

This is all good, but is sometimes bewildering to patients. Why so many tests? Advances in technology add another layer of protection for selected patients.


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