Tissue marker migration after MRI-guided breast biopsy: Migration frequency and associated factors.

The purpose of this study was to determine the frequency and associated risk factors contributing to immediate tissue marker migration in patients undergoing MRI-guided breast biopsy and to evaluate how often tissue marker migration altered clinical management. Between July 2010 and May 2015, we retrospectively reviewed all MRI-guided breast biopsies at our institution for tissue marker migration. Migration was defined as final position of the tissue marker >10 mm from the target site based on the expected location of the MRI finding on postprocedure mammogram. Factors associated with migration were analyzed using Fisher's exact test and Chi-squared test, with P < .05 considered statistically significant. A total of 278 patients underwent 298 MRI-guided biopsies. Migration occurred in 42/298 biopsies (14%). Almost entirely fat fibroglandular tissue was identified as an independent risk factor for tissue marker migration, occurring in 6/16 (38%), compared to 36/262 (14%) for the other fibroglandular tissue categories (P = .03). Biopsy target size was significantly associated with clip migration, occurring in 25/114 (22%) lesions <10 mm in size vs 17/184 (9%) for larger lesions (P = .003). Clinical management was affected by clip migration in 6/42 cases (14%) with one requiring ultrasound-guided biopsy cavity marker placement and five requiring biopsy cavity wire localization. Radiologists must be vigilant in assessing for clip migration as it is not an infrequent complication. Given migration may change clinical management and require altered procedures for localization of the biopsy cavity, the possibility of clip migration should be included in informed consent.