Digital breast tomosynthesis seems like a great idea for breast imaging because it eliminates the difficulties inherent in rendering a three dimensional object on a two dimensional image. I spend a lot of time trying to decide if a finding is real or just overlapping structures.
The women return for additional views, worried that a breast cancer has been detected. They do not realize that questions about the breast can remain after a screening mammogram. The women think the screening mammogram is perfect in detecting cancer. If they are asked to return to the imaging facility for additional views, they have breast cancer. They are scared when they return for the workup.
According to Dr. Edward Sickles in a July Society of Breast Imaging forum post, “The largest published consecutive case series of such findings reports that over 80 percent represent summation artifact, so it makes sense to approach the diagnostic evaluation with the goal of establishing or excluding the diagnosis of summation artifact.” A Yale study presented at the ARRS meeting in May 2012 showed a 40 percent reduction in recalls using digital breast tomosynthesis. The largest decrease in recalls was in evaluation of asymmetries and calcifications. The recall rate for asymmetries dropped from 7.1 percent with conventional screening mammography to 2.8 percent with digital breast tomosynthesis and 2D digital mammography.
Clinical trials are underway to compare digital breast tomosynthesis to conventional digital mammography in detection of breast cancers. The Oslo study of tomosynthesis in the Oslo Breast Cancer Screening Program will compare several combinations of mammographic examinations including conventional digital 2D mammograms, 2D plus computer-aided detection, 2D plus digital breast tomosynthesis and synthetic 2D plus digital breast tomosynthesis. Other clinical trials compare the ability to detect breast cancer with digital mammography or digital breast tomosynthesis.
Digital breast tomosynthesis has been enthusiastically adopted by some practices, while others take a wait and see position. Those waiting are concerned about decisions concerning which women are offered digital breast tomosynthesis, radiation dose to the breast (similar to analogy mammography) and lack of reimbursement by insurance companies.
Earlier this year, I attended the eight-hour digital breast tomosynthesis class taught by Drs. Betty Rafferty and Phoebe Freer. The case material was convincing particularly in the lesions that are difficult to see on regular digital mammogram, like the subtle architectural distortions. I became a proponent of the technology at that point.
But, I will say, the results of the clinical trials are scientific evidence of the benefits of an additional technology for the detection of breast cancer. I may have to wait with bated breath. If the teaching cases are representative, digital breast tomosynthesis is a great addition to the tools of diagnosis of breast cancer.
