Beyond the Needle: Understanding Tissue Marker Migration in Breast MRI-Guided Biopsies.

Objective: To evaluate the frequency and factors associated with clip migration in MRI-guided breast biopsies.

Methods: This study was approved by our Institutional Review Board and was compliant with HIPAA. We retrospectively evaluated all MRI-guided biopsies performed between January 2013 and December 2020 in our institution for clip migration. Only patients with follow-up breast MRI showing the clip were included in the study. Migration was defined as movement of the clip of 10 mm or more from the target lesion. Migration frequency and directions were recorded. Factors associated with clip migration were analyzed using statistical tests as appropriate.

Results: A total of 291 biopsies in 268 women were included in the study with 31 migration events recorded (11%; 95% CI, 7%-15%). All migrations occurred along the biopsy tract; 97% (30/31) of them displaced distal to the needle entry site. More than 50% regional fat (around the target lesion) was the strongest factor associated with migration, seen in 21/141 women (15%), compared to 10/150 (7%) with 50% or less local fat (P = .023). Global fatty breast was more loosely associated with migration, showing borderline significance (P = .06). Other factors did not correlate with clip migration, including lesion size, depth, or location; pathology result; breast thickness; or biopsy approach.

Conclusion: Although clip migration after breast MRI-guided biopsy is an uncommon event, it occurs more often when the target lesion is surrounded by fat, with the clip usually displaced away from the needle entry site.