Imaging Methods for the Breast Cancer Diagnosis

Once women reach a certain age, around 40 years old, they should receive a breast cancer screening mammogram every year. A mammogram uses X-ray radiation to create films or digital pictures of the breast tissue so that a radiologist can determine if there are any abnormalities present. The use of screening mammograms has led to the improved early detection of breast cancer and has saved countless lives since it widespread use in the 1980s.

Unfortunately many women find the mammogram procedure very uncomfortable and some even find it to be painful, mainly because each breast is held and pressed firmly by the mammography device. Despite the direct and undeniable improvement in cancer detection and diagnosis, women often fall short of the yearly mammogram mark. Even though the technology has been successful, mammography is an imperfect means of detecting breast cancer. Because of compliance issues and technical imperfections, the National Cancer Institute and other federal and private agencies have funded numerous research projects both to improve the mammogram procedure and to find inexpensive screening methods that improve the accuracy (and comfort) of breast cancer screening.

 

 

One research effort has been to use ultrasound for breast cancer diagnosis. Ultrasound, similar to the technology used on pregnant women and their fetuses, uses sound waves to “visualize” the breast tissue based on how the sound waves are reflected. The main benefit of ultrasound is that it is painless. Breast ultrasound can be used to distinguish between solid tumors and fluid-filled cysts and can be used to guide a fine or core needle for tissue aspiration and biopsy. Unfortunately, ultrasound cannot detect microcalcifications as an X-ray or mammogram can, and the presence of clustered microcalcifications can indicate a young tumor. Therefore ultrasound is unlikely to become a routine breast cancer screening tool.

Magnetic resonance imaging or MRI is a newer imaging technology that has been applied to the diagnosis of breast cancer. Instead of X-rays or other radiation, an MRI uses a powerful magnet to investigate tissues within the body. In a breast MRI, the woman lies face down on the examination table with her breasts descending into a recessed portion of the table. She is then moved into the “tube” that is surrounded by an electromagnet. The technique may seem claustrophobic to some, but it is painless and uses no radiation. Currently breast MRI is not a general screening technique since, like ultrasound, it cannot detect microcalcifications. In some women that are at particularly high risk for certain breast cancers, breast MRI may be the screening tool of choice. Unfortunately MRI exams are still quite expensive, not always covered by health insurance and may lead to false positives (a test result that looks like cancer but actually is not).

 

PET, which stands for positron emission tomography, is a breast imaging technique that requires the injection of a small amount of radioactive substance attached to a sugar molecule. Cancers use more sugar than normal breast tissue thus when the breast is imaged with a detector, breast tumors appear as highly concentrated regions of radioactivity. The obvious drawback to PET imaging is the injection of a radioactive substance, albeit a very small amount. In addition the technique does not seem to be useful as screening tool. Where PET may be useful is in determining the stage and spread of breast cancer.

 

Perhaps the most promising tool for breast cancer screening is the breast CT scan. Since this technique uses X-rays, it can detect microcalcifications. It also provides radiologists with an excellent view of the breast anatomy. Patients report that breast CT is much more comfortable than traditional mammography. While there are certain technical and diagnostic features that need to be worked out, breast CT represents a promising breast cancer screening and diagnostic tool.