Routine two-dimensional digital mammogram
Figure 1. Routine two-dimensional digital mammogram interpreted as "normal."

Radiologists and breast imaging specialists at Penn Medicine are using digital breast tomosynthesis, or DBT, to perform three-dimensional mammography for breast cancer screening and diagnosis. DBT is an offering of the Breast Imaging Division at Penn Radiology.

The DBT system employs a digital X-ray that records a series of low-dose, high-resolution images of the breast while traversing a small (15°) arc around the compressed breast. As the projection angle changes, images are recorded at slightly different depths and thicknesses, from one surface of the breast to the other. The compression time of approximately four seconds needed for DBT is similar to that used for standard two-dimensional digital mammography.

Following the procedure, the images are reconstructed in a computer to produce a 3D rendering of the interior breast architecture. This rendering appears as a stack of images of the breast that, in total, represent the area from one skin surface to the other. Each DBT image can then be peeled apart, magnified or manipulated to better reveal minute detail.

In clinical studies and case reports, DBT has demonstrated improved specificity and sensitivity in breast cancer screening across all breast densities, subjective improvement in lesion conspicuity for benign and malignant lesions, and potential improvement in cancer detection, particularly the unmasking of obscured cancers. [1]

DBT offers a clarity and degree of detail sufficient to reduce many of the false-positives and false-negatives associated with conventional 2D mammography (particularly the superimposition of overlapping tissue shadows) to allow more accurate interpretation of breast changes. In a number of small series studies, researchers report reductions as high as 40% in the false-positive callback rate. In addition, 3D mammography has been shown to identify significantly more invasive, or potentially lethal, cancers than traditional mammography.

DBT is not yet the standard of care for breast mammography, and some minor concerns remain to be clarified in clinical studies. The approved indications fro DBT state that it must be used as an adjunct to standard digital mammography, which means that the radiation dose for women having DBT is slightly higher than it would be with standard 2D digital mammography alone. Even when added to 2D imaging, however, the dose with DBT remains lower than the maximum allowed with the analog mammography in use prior to the turn of the century.

Case Study

Ms. G, a 49-year-old woman, had a routine annual mammogram at her community hospital that was interpreted as “normal” (Figure 1). Concerned about a family history of breast cancer in women in her age group, Ms. G had a bilateral DBT study at Penn Medicine several months later.

Magnified tomosynthesis view of the right breast revealing an irregular, suspicious mass
Figure 2. Magnified tomosynthesis view of the right breast revealing an irregular, suspicious mass not seen on routine mammography (arrow).

In this study, the tomosynthesis view of her right breast revealed an irregular, suspicious mass that was not visible on the standard 2-D mammographic view. A magnified view provided further definition of the mass, which on biopsy was found to be an invasive ductal carcinoma (Figure 2, arrow). Ms. G was then referred to the Breast Cancer Program at the Abramson Cancer Center for further evaluation.

Access

Penn Radiology
Perelman Center for Advanced Medicine
Atrium, Ground Floor
3400 Civic Center Boulevard
Philadelphia, PA 19104

Published on: February 9, 2018

References

  1. Conant E F. Clinical Implementation of Digital Breast Tomosynthesis. Radiol Clin North Am 2014;52:499-518.

About Penn Radiology

The Department of Radiology at Penn Medicine is a highly specialized, full service department that strives to meet all patient and clinician needs in diagnostic imaging and image-guided therapies. The Breast Imaging Division, accredited by the American College of Radiology, provides screening and problem-solving mammography for outpatients at the Perelman Center for Advanced Medicine. The basic examination uses state-of-the art, low-dose, film screen equipment with the capability for supplemental clarification with magnification, spot-compression, and special projects.

Penn Faculty Team

Julia A. Birnbaum, MD

Clinical Assistant Professor of Radiology

Alice Chong, MD

Chief of Breast Imaging, Pennsylvania Hospital

Assistant Professor of Clinical Radiology

Emily F. Conant, MD

Division Chief, Breast Imaging

Vice Chair, Faculty Development, Radiology

Professor of Radiology at the Hospital of the University of Pennsylvania

Susan Roth, MD

Professor of Radiology at the Hospital of the University of Pennsylvania

Jennifer D. Tobey, MD

Clinical Assistant Professor of Radiology

Susan P. Weinstein, MD

Associate Professor of Radiology at the Hospital of the University of Pennsylvania

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