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+++++++++++++++++++++++++++++++++++++ + + +++++++++++++++++++++++++++++++++++++ SPECIAL SECTION: TECHNOLOGY +++ +++ Breast Digital Tomosynthesis By Young C. Kim, MD D IGITAL TOMOSYNTHESIS CREATES a 3-dimensional picture of the breast using x-ray. Digital tomosynthesis of the breast is different from a standard mammogram in the same way a CT scan of the chest is different from a standard chest X-ray. Digital tomosynthesis is analogous to geometric tomography. The difference is that in digital tomosynthesis, the X-ray tube makes one sweep and produces many slices, while with geometric tomography, each sweep produces one slice. This is enabled by the rapid readout capabilities of flat panel digital detectors. A series of low-dose exposures is made during the sweep, and the exposures are reconstructed to produce slices at different planes within the patient.1,2 Mammography usually takes two X-rays of each breast from different angles: top to bottom and side to side. The breast is pulled away from the body, compressed, and held between two glass plates to ensure that the whole breast is viewed. Regular mammography records the pictures on film, and digital mam- mography records the pictures on the computer. The images are then read by a radiologist. Breast cancer, which is denser than most healthy nearby breast tissue, appears as irregular white areas — sometimes called shadows. Mammograms Are Very Good, But They Have Some Significant Limitations: + The compression of the breast that is required for a mam- mogram can be uncomfortable. Some patients hate it, and it could deter them from getting the test. + Breast compression also causes overlapping of the breast tissue. A breast cancer can be hidden in the overlapping tissue and not show up on the mammogram. + Mammograms take only one picture, across the entire breast, in two directions: top to bottom and side to side. Tomosynthesis Has Several Benefits: + Digital tomosynthesis takes multiple X-ray pictures of each breast from many angles. The breast is positioned the same 22 | Cleveland-Akron-Canton MD NEWS ■ MDNEWS.COM ■ SEPTEMBER-OCTOBER 2012 way it is in a conventional mammogram, but only a little pressure is applied — just enough to keep the breast in a stable position during the procedure. + By minimizing the impact of overlapping breast tissue, tomosynthesis can make a tumor easier to see and can help detect small cancers earlier than standard mammography. + Tomosynthesis can help radiologists reduce false alarms. For example, a 3-D view can prove that a spot that looked questionable in 2-D view is really no cause for concern. This leads to fewer callbacks, fewer additional scans and biopsies and less anxiety for patients.3 Limitations of Tomosynthesis Include: + Breast digital tomosynthesis is currently not widely avail- able other than at academic university hospitals and large metropolitan hospitals. + The cost of the tomosynthesis is not paid by most health insurance companies yet and needs to be paid by the patients. + It takes more time to read tomosynthesis, as the images are anywhere between 40 to 75 for each view, total being 4 views, depending on how large the breasts are. References 1. Bushberg JT, Siebert JA, Leidholt EM, Boone JM. The Essential Physics of Medical Imaging. 2nd ed. New York, NY. Lippincott Williams & Wilkins; 2002 2. Brice J. Will New DR Technologies Offer Alternative to CT? Part 2. http:/www.auntminnie.com/index.aspx?Sec=sup&Sub 3. Digital Tomosynthesis-Breastcancer.org Dr. Young C. Kim is a board-certified radiologist and co-medical director of the Breast Center at Southwest General Health Center. ■