Document Type : Original Article
Assistant Professor of Radiology,Tufts Medical Center
Digital breast tomosynthesis (DBT) has been introduced to the market in 2011 and is more and more affecting the practice. Like other new technologies there has been positive and negative speculations around it. Almost all major centers in the United States have started using this technology in diagnostic arena and less common for screenings.
In contrary to full field digital mammography (FFDM), which acquires one image from the compressed breast, DBT or 3D mammography obtains multiple images form the compressed breast tissue. Current machines either obtain FFDM subsequently to the 3D acquisition or create a synthetic 2D image (C-view, V-preview, Insight 2D) from 3D images.
In this session we are going to review the key features of DBT including technique, clinical implementation and performance, imaging findings and benefits of DBT in screening/ Diagnostic workup, as well as pro and cons of breast tomosynthesis:
The acquisition technique from patients’ stand point is not different.
Recall rate (BIRADS 0): 15% -37% decrease in recall rate based on different studies.
Short term follow up recommendations (BIRADS 3): decreased in number of BIRADS 3.
Increase in cancer detection rate / CDR.
CDR is number of cancers per 1000 screening studies: The cancer detection rate has increased by 1.2 -2.7 per 1000 screeners based on some studies. Two large studies demonstrated up to 40% increase in number of detected invasive cancers while detection rate of DCIS remained similar.
Dense Breasts: DBT does not overweight FFDM in dense breast based on some studies, but overall improves lesion conspicuity in dense breast. Ultrasound has increased yield of cancer detection by 2-4 per 1000 in patients with dense breasts who had negative mammography.
Radiologist comfort: decreased workflow by lower number of recalls or diagnostic studies.
Radiation dose: DBT followed by FFDM glandular radiation dose is twice the dose of FFDM alone, however, is still below the FDA safe margin of 3 mGy per view. By advent of synthetic C-view, now the FFDM and DBT glandular radiation dose is similar. The effective radiation dose from DBT and FFDM is less than 1- 2 months of background radiation we receive by living on planet earth. Background radiation in the United Stated is 3 mSv.
Challenges: Slow image transmission and and storage issue in long run, large or thick breasts, microcalcification detection, increased time of interpretation.
Cost effectiveness: 3D mammography is cost effective compared to 2D mammography in patients 40 years and older when counted for quality of life.