MRI: Better Than Mammography for Diagnosing Breast Cancer?
In the fight against breast cancer, there's a new method of early detection that may be more accurate that the mammogram.
Mammography is currently the most common method used to detect breast cancer, but it is only effective in women older than age 40 and often is not an option for women with very dense breasts.
Throughout the month of October — National Breast Cancer Awareness month — the idea that magnetic resonance imaging (MRI) may some day replace the mammogram has been much talked about.
The method has been hailed by experts as more effective in detecting early breast cancer than mammography. The only problem? It's an expensive method — the test can run about $1,000 compared to $100 for a mammography — and some insurance companies won't cover the procedure.
Some recent studies, conducted by the National Cancer Institute (NCI), found that MRI was not only more effective than mammography, but also better than ultrasound or other clinical breast exams in finding breast cancer in woman who had the screening.
A study conducted by the NCI between 1998 and 2002 found that MRIs were accurate in detecting breast cancer in 83 percent of the 54 women who participated in the study. The MRI returned a false positive in 17 percent of its diagnoses.
Still, more research is needed to support the fact that it is the better option in detecting breast cancer. Dr. Mitchell Schnall, professor of radiology at the University of Pennsylvania and the principal investigator for the NCI-funded group of researchers at the American College of Radiology Imaging Network (ACRIN) studying the benefits of MRI, believes mammograms should not be replaced by MRI.
“Mammography is the traditional way of finding breast cancer,” said Schnall. “In mammogram imaging, you can feel it.
“An MRI finds breast cancer by highlighting areas that have high blood flow which can signal possible cancer," continued Schnall. "It’s something that adds more contrast to images of blood flow."
Mammography is also better at detecting breast cancer calcifications, tiny calcium deposits within the breast tissue that appear as white spots on a mammogram, said Schnall. These calcifications are common, and most women have at least one, but tighter clusters of calcifications in irregular shapes may indicate breast cancer. Schnall said MRI may or may not pick up on calcifications.
Schnall added that women should consider having an MRI if they feel they are at risk of acquiring breast cancer. However, the extra cost of an MRI can be an impediment for some so they should only get one if they have had breast cancer in their family or feel they are in the high risk category.
“I don’t recommend doing all women, but I recommend women who are at (high) risk," he said. "Studies show that an MRI can pick up more cancer. Right now, it’s too costly to do study on the benefits on the general population, but it has proven good at detecting cancer.”
There can also be some hit or miss with mammography as well, according to one radiologist. “It is well known that mammography is not 100 percent sensitive in detecting all breast lesions,” said Dr. Michal Schneider-Kolsky, PhD, a senior lecturer at the School of Biomedical Sciences at Monash University in Victoria, British Columbia. “Miss rates vary on average by 10 to 20 percent depending on each clinic. Many clinics perform double reporting in order to reduce the miss rate. Ultrasound is the second line of investigation if there is a suspicion. Again, ultrasound can miss some lesions and patients may then be referred to MRI. At this stage, only a small number of patients will have an MRI since most clinics do not have the specific set up to perform breast MRI and because of the costs involved.”
Schnall and his colleagues will continue to focus on MRI and other screenings and their efficiency in detecting breast and other cancers — breast cancer being their largest area of research. So far, the group has 20 different trials, which are in various stages, and are tracking various aspects of imaging in detecting different cancer.
In addition to detecting cancer, they are also looking to MRI as an indicator in the effectiveness of cancer treatments. “We’re looking at MRI as a response marker in chemotherapy, so we can tell if chemotherapy is working early on, or if it is not working,” added Schnall.
Schneider-Kolsky and his colleagues are currently conducting a preliminary study of the usefulness of a targeted ultrasound after MRI in detecting breast lesions. He added that MRI can be the better option, but agrees that more research needs to be done to evaluate its effectiveness for screening the general population. Costs also need to be adjusted, so more women will not feel deterred by having an MRI if needed.
“MRI has, over the last 10 years or so, found a role in breast lesion evaluation," said Schneider-Kolsky, "specifically for preoperative planning for conserving surgery in infiltrating and in situ cancers, assessment of other lesions in the breast (same breast or other side), evaluation of lesion recurrence after lumpectomy or chemotherapy, screening in women at high risk for breast cancer, and also in the evaluation of suspicion of breast cancer when other imaging modalities (mammography/x-ray and ultrasound) were negative or equivocal.”