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Scientific Session 21 — SS21: Breast - Screening and Interventional

Thursday, April 26, 2018

Abstracts 1094-3260

3260. Evaluation of a Novel Nonradioactive Magnetic Seed Wireless Localization Program

Lamb L*,  Bahl M,  Specht M,  D'Alessandro H,  Lehman C. Massachusetts General Hospital/Harvard Medical School, Boston, MA

Address correspondence to M. Bahl (

Objective: Conventional techniques for preoperative localization of nonpalpable and percutaneously biopsied breast lesions include needle-wire assemblies and radioactive seeds. A novel localization technique with the use of nonradioactive magnetic seeds has not previously been studied. The purpose of this study is to evaluate the feasibility and effectiveness of magnetic seed localization.

Materials and Methods: A retrospective review was performed of consecutive women who underwent image-guided needle localization with magnetic seeds and subsequent surgical excision from March to August 2017. Patient age, lesion type, pathology results from image-guided core needle biopsy, number of localization markers placed, type of imaging guidance used for marker placement, operative reports, and surgical margin status were reviewed.

Results: Over the study period, 188 patients (mean age, 58.8 years; range, 22–89 years) underwent image-guided localization with magnetic seeds and subsequent surgical excision. In all, 164 patients had a single localization marker placed, and 24 patients underwent bracketing or had more than one lesion localized, for a total of 213 localization marker placements. Indications for marker placement included invasive carcinoma (96, 45.1%), ductal carcinoma in situ (41, 19.2%), high-risk lesions (71, 33.3%), and lesions that were benign but discordant at core needle biopsy (5, 2.3%). Localization markers were most commonly placed for masses (96, 45.1 %) and calcifications (68, 31.9%) and were placed either under mammographic guidance (162, 76.1%) or sonographic guidance (51, 23.9%). Technical success, defined as placement of the magnetic seed within 1 cm of the target, was achieved for 206 of 213 markers (96.7%). Seven (3.3%) markers were displaced more than 1 cm from the target, all of which were deployed using an upright digital breast tomosynthesis system during our institution’s initial experience with tomosynthesis-guided needle localization procedures. All 213 markers were successfully retrieved at surgery. Of 137 cases of in situ or invasive carcinoma, 30 (21.9%) had tumor-positive surgical margins requiring reexcision. No major or minor complications were observed during marker placement or intraoperatively.

Conclusion: Image-guided needle localization with magnetic seeds is a safe, feasible, and effective method for localizing nonpalpable and percutaneously biopsied breast lesions. Magnetic seed localization has the potential to replace conventional wire needle localization and radioactive seed needle localization for lesions that require surgical excision.