Metallic clip deployment during stereotactic breast biopsy: Retrospective analysis

PURPOSE: To determine the visibility of presumably excised lesions on screen-film mammograms obtained after biopsy and to determine the accuracy of clip deployment on the basis of measurements obtained on routine pre- and postbiopsy mammograms. MATERIALS AND METHODS: One hundred eleven cases of core-needle biopsy with clip deployment were reviewed. In each, the type of lesion, lesion location, and biopsy approach were recorded. Pre- and postbiopsy images were reviewed, and the distance between the clip and biopsy site was measured. Postbiopsy images were reviewed to determine whether the targeted lesion remained visible. RESULTS: In 62 (56%) cases, the clip was located within 5 mm of the target on postbiopsy images (craniocaudal and mediolateral), while in 18 (16%), the clip was within 6-10 mm on one projection. However, 31 (28%) clips were more than 1 cm from the target on at least one postbiopsy image. Of the 111 cases, 39 (35%) were malignant or atypical and required excision. Of these, 18 (46%) had clips at least 7 cm from the targeted lesion on at least one projection. CONCLUSION: Metallic clips placed during core-needle breast biopsy are intended to mark the biopsy site when the visible lesion is excised, in case additional biopsy is required. The data suggest that the position of metallic clips placed during stereotactic core-needle biopsy may differ substantially from the location of the biopsy site. Postbiopsy mammography should be performed in two orthogonal planes to document clip position relative to the biopsy site.