3D mammography or digital breast tomosynthesis is a new imaging technology that can identify small cancers not visible on traditional 2D mammography. If cancers are found when they are small, treatment options are generally less traumatic and the chance for a cure is greater.
The test is performed with dedicated tomosynthesis equipment that takes a series of low-dose pictures prior to each mammographic view. The computer in the unit then takes all those pictures and combines them into a 3-dimensional representation of the breast. This allows the radiologist to view the breast in layers without having to look through dense breast tissue above or below each layer. For the time being, the Food and Drug Adminstration requires that 3D mammography be performed in conjunction with standard 2D mammography. Efforts are under way to have the FDA approve 3D mammography without the need for a 2D mammogram.
Another benefit of 3D mammography is its ability to reduce stress-inducing additional studies. As many as 10% of women who have a routine screening mammogram will be asked to have additional mammographic views and possibly an ultrasound. The majority of these women - up to 80 percent - will experience what’s called a “false-positive” which means that an area that looked suspicious on their screening mammogram turned out, upon further testing, to be normal.
Since current mammography relies on a 2D image, it has limitations because the breast is a 3-dimensional organ composed of different structures, such as blood vessels, milk ducts, fat, and ligaments. All of these structures can overlap and cause confusion when viewed as a 2-dimensional, flat image which is the leading reason why small breast cancers may be missed and normal tissue may appear abnormal.
Breast cancer is seen clearly on 3D, but is difficult to see on2D mammography
Although patients will notice little difference between 2D and 3D mammograms, the 3D technology gives the radiologist a clearer view through the overlapping structures of breast tissue. Reading a breast tomosynthesis exam is like flipping through the pages of a book to view one page at a time instead of seeing the whole breast reduced to a single frame, as is the case with conventional 2D mammography. The ability to look at each layer of breast tissue millimeter by millimeter allows doctors to identify individual structures in the breast free from the confusion of overlying tissue.
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