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Digital breast tomosynthesis uses modified digital mammography equipment to obtain additional radiographic data that are used to reconstruct cross-sectional “slices” of breast tissue. Tomosynthesis may improve the accuracy of digital mammography by reducing problems caused by overlapping tissue. Tomosynthesis typically involves additional imaging time and radiation exposure, although recent improvements may change this.
Conventional mammography produces two-dimensional (2D) images of the breast. Overlapping tissue on a 2D image can mask suspicious lesions or make benign tissue appear suspicious, particularly in women with dense breast tissue. As a result, women may be recalled for additional mammographic spot views. Inaccurate results may lead to unnecessary biopsies and emotional stress, or to a potential delay in diagnosis. Spot views often are used to evaluate microcalcifications, opacities, or architectural distortions; to distinguish masses from overlapping tissue; and to view possible findings close to the chest wall or in the retro-areolar area behind the nipple. The National Cancer Institute reports that approximately 20% of cancers are missed at mammography screening. Average recall rates are approximately 10%, with an average cancer detection rate of 4.7 per 1000 screening mammography examinations. The Mammography Quality Standards Act audit guidelines anticipate 2 to 10 cancers detected per 1000 screening mammograms. Interval cancers, which are detected between screenings, tend to have poorer prognoses.
Digital breast tomosynthesis was developed to improve the accuracy of mammography by capturing 3-dimensional (3D) images of the breast, further clarifying areas of overlapping tissue. Developers proposed that its use would result in increased sensitivity and specificity, as well as fewer recalls due to inconclusive results. Digital breast tomosynthesis produces a 3D image by taking multiple low-dose images per view along an arc over the breast. During breast tomosynthesis, the compressed breast remains stationary while the x-ray tube moves approximately 1° for each image in a 15° to 50° arc, acquiring 11 to 49 images. These images are projected as cross-sectional “slices” of the breast, with each slice typically 1-mm thick. Adding breast tomosynthesis takes about 10 seconds per view. In one study in a research setting, mean time for interpretation of results was 1.22 (1.15) minutes for digital mammography and 2.39 (1.65) minutes for combined digital mammography and breast tomosynthesis.
With conventional 2D mammography, breast compression helps decrease tissue overlap and improve visibility. By reducing problems with overlapping tissue, compression with breast tomosynthesis may be reduced by up to 50%. This change could result in improved patient satisfaction.
A machine equipped with breast tomosynthesis can perform 2D digital mammography, 3D digital mammography, or a combination of both 2D and 3D mammography during a single compression. Radiation exposure from tomosynthesis is roughly equivalent to mammography. Therefore, adding tomosynthesis to mammography doubles the radiation dose, although it still is below the maximum allowable dose established in the U.S. Mammography Quality Standards Act.
Studies typically compare 1-view (ie, mediolateral oblique [MLO] view), or more commonly, 2-view (MLO plus craniocaudal view) breast tomosynthesis alone or combined with standard 2D mammography to standard 2D mammography alone. A 2014 TEC Assessment focused on 2-view tomosynthesis. The FDA Radiological Devices Panel, which reviewed this new modality in 2011, recommended that 2- view breast tomosynthesis is preferable to 1-view tomosynthesis (both used in combination with full-field digital mammography).
In May 2013, the U.S. Food and Drug Administration (FDA) approved new tomosynthesis software that permits creation of 2D images (called C view) from images obtained during tomosynthesis. As a result, 2D mammography may become unnecessary, thereby lowering radiation dose. In other words, only the tomosynthesis procedure will be needed, and both 2D and 3D images will be created. It is too early to gauge how traditional mammography plus tomosynthesis compares with C view plus tomosynthesis.
The Selenia® Dimensions® 3D System manufactured by Hologic Inc. (Bedford, MA), received FDA approval on February 11, 2011, through the premarket application (PMA) approval process (PMA P080003). Currently, it is the only commercially available tomosynthesis system with FDA approval. This system is a software and hardware upgrade of the Selenia® Dimensions 2D full-field digital mammography system, which FDA approved in 2008. Facilities using a digital breast tomosynthesis system must apply to FDA for a certificate extension covering use of the breast tomosynthesis portion of the unit. The Mammography Quality Standards Act requires interpreting physicians, radiologic technologists, and medical physicists to complete 8 hours of digital breast tomosynthesis training, and mandates a detailed mammography equipment evaluation before use. In May 2013, FDA also approved Hologic's C-View 2D imaging software. This software is used to create 2D images from the tomosynthesis results, rather than perform a separate mammogram.
Several other manufacturers are working toward FDA approval of their digital breast tomosynthesis systems. GE Healthcare is seeking FDA approval for breast tomosynthesis, specifically as an add-on option for the Senographe™ Essential mammography device. FDA has agreed to a modular PMA submission, which means that GE Healthcare will submit the request in different sections. The first of 4 sections was submitted in November 2011. Three completed trials sponsored by GE are listed at online site ClinicalTrials.gov. They focus on the use of breast tomosynthesis in routine screening (NCT00535678), in diagnostic mammography (NCT00535327), and for breast biopsy (NCT00535184). Results do not appear to have been published to date.
POLICYDigital breast tomosynthesis is considered investigational in the screening or diagnosis of breast cancer.
POLICY EXCEPTIONSFederal Employee Program (FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
POLICY GUIDELINESInvestigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY07/21/2011: Approved by Medical Policy Advisory Committee.
09/25/2012: Policy reviewed; no changes.
11/06/2013: Policy reviewed; no changes.
09/23/2014: Policy reviewed; description revised. Policy statement unchanged.
SOURCE(S)Blue Cross Blue Shield Association policy # 6.01.53
This may not be a comprehensive list of procedure codes applicable to this policy.