Stereotactic core biopsy of breast microcalcifications: Comparison of film versus digital mammography, both using an add-on unit

OBJECTIVE. The goal of this study was to assess the accuracy of an add-on stereotactic unit for core biopsy of indeterminate breast microcalcifications and to compare digital with conventional stereotactic guidance. MATERIALS AND METHODS. We conducted a retrospective review of 232 lesions with indeterminate microcalcifications in 218 women who underwent stereotactically guided breast biopsies. All biopsies were performed using a standard mammography machine with an add-on unit, 121 with conventional and 111 with digital stereotactic guidance. Successful sampling of the lesion was determined by the detection of microcalcifications on specimen radiography or at pathology. RESULTS. Using the add-on unit, 219 (94.4%) of the 232 targeted lesions were successfully sampled. The size, location, number of cores per lesion, and histology of the lesions were not different between the conventional and digital stereotactic biopsy groups (p > 0.1). Indeterminate microcalcifications were missed on biopsy in nine (7.4%) of 121 cases using conventional radiography and in only four (3.6%) of 111 cases using digital imaging. Digital stereotactic guidance allowed sampling of lesions with fewer calcifications per square centimeter (p < 0.001). CONCLUSION. Sampling of indeterminate microcalcifications using a standard mammography machine and an add-on unit has a high accuracy, similar to rates reported for dedicated prone biopsy tables. An add-on unit offers the advantage of considerable cost and space savings. Relative to conventional radiography, digital stereotactic guidance allows lesions with fewer calcifications to be sampled and achieves a greater biopsy success rate. Immediate digital images in the biopsy room also permit rapid adjustment of alignment and minimize patient movement.