Society of Breast Imaging (SBI) President John Lewin, MD, associate professor of radiology and biomedical imaging, and division chief, breast imaging, at the Yale School of Medicine, discusses the types of supplemental breast imaging used to aid in cancer detection in women with dense breast tissue.

Dense breast tissue can hinder the ability to read mammograms, because dense tissue is similar in appearance to breast cancer. For this reason, supplemental breast imaging is often used to determine if suspicious areas are cancer or not. These supplemental imaging modalities include contrast enhanced breast magnetic resonance imaging (MRI), contrast enhanced mammography, breast ultrasound and molecular breast imaging, also called nuclear breast imaging.  

"MRI dominates the contrast enhanced imaging area because it was there first and because there are MRI machines available at most hospitals and there is no big purchase that needs to be made," Lewin said. "There are other competitors. They have not gained widespread adoption yet, but they will."

He said the most likely competitor to breast MRI is contrast enhanced mammography, which has performance very similar to MRI, but does not require an MRI machine, just a regular mammography machine and IV contrast. He said the biggest barrier holding back this technology is that reimbursement is higher for MRI for basically the same exam. This has driven most centers to continue using MRI, even though it would be easier and less time consuming to use contrast enhanced mammography.

"Until that changes, the adoption of contrast enhanced mammography will continue to be slow," Lewin said. 

Molecular breast imaging is another option, which uses the injection of a radioactive tracer and areas of high metabolism and blood flow light up in the image, indicating a cancer.

"This technology also has been slow to gain widespread adoption, but for other reasons," Lewin said. "It actually does have a billing code, but it requires purchasing a specialized piece of imaging equipment, which is a barrier."

He said breast ultrasound can be used for screening, but Lewin said it is usually considered best to get a mammogram first and then an ultrasound. Often, insurance will reimburse for an ultrasound if required because of the diagnosis quality of a dense breast mammogram, and usually the ultrasound can be done during the same visit as the mammogram. But, the diagnostic value of a mammogram and ultrasound are about equal, so he will not argue with a patient who just wants the ultrasound. 

Another supplemental imaging system used is automated breast ultrasound (ABUS). This system uses an automated sweep of the breast to improve consistency between exams and monographers, as some breast imaging centers may not have an experienced breast ultrasound imager one staff. The technology also allows for better consistency in comparisons between views and measurements on prior ABUS exams, which can be important for tracking tumors or suspicious areas.