Conventional 2D mammography images the whole breast in one exposure. Two images of each breast at orthogonal angles to one another are then acquired in order to aid the physician in creating a mental 3D picture of the breast. This is to ensure that the doctor is able to extrapolate information from 2D pictures and then subsequently find them in 3D space, in this case, the breast. The Achilles heel of conventional 2D mammography is the ability to find cancer in women with mammographically dense breasts. While it is fairly straightforward to visually detect cancer in a fatty breast, only about 50 percent of cancers will be visible in extremely dense breasts.
There are several new technologies today to help the radiologist overcome this fundamental weakness in imaging. One of the most promising techniques is called digital tomosynthesis. Digital tomosynthesis produces a 3D view of breast tissue. The x-ray tube is moved through a limited arc angle while the breast is compressed and a series of images are acquired. The series, usually about 16 images, are then reconstructed to form a three-dimensional image set.
3D Imaging Benefits
The potential benefits include greater conspicuity of abnormalities by elimination of overlapping fibroglandular structures, fewer callbacks for additional imaging thereby reducing patient anxiety, better visualization leading to improved categorization of size, shape and location of tumor, fewer false positive findings requiring biopsy, and finally, better visualization of potential multifocal sites of tumor.
The radiation dose for digital tomosynthesis is under the FDA regulated limit for mammography. Adding tomosynthesis does involve a minimal amount of additional radiation compared with a standard mammogram.
Future Use of Tomosynthesis
While preliminary clinical studies have shown efficacy, more rigorous studies are currently underway to establish the potential applications of tomosynthesis.
What are the future applications of tomosynthesis?