• Diana M Lanners, Kimberly K Amrami, Renee S Jonsgaard, John J Gisvold, and Joel P Felmlee.
• Department of Radiology, Mayo Clinic, 201 1st St. SW, Rochester, MN 55905, USA.
• AJR Am J Roentgenol. 2004 Sep 1; 183 (3): 825-9.

ObjectiveThe purpose of our study was to assess the MRI risk factors for the patient after an unusual case of inadvertent deployment of the mounting sheath of a metallic clip used at stereotactic breast biopsy.Materials And MethodsWe evaluated the materials for ferromagnetic properties, heating, and artifacts.ResultsOur analysis showed significant deflection and prominent susceptibility artifacts of the sheath at 1.5 T, although the clip itself showed no deflection and only minimal artifact. Our study shows that a device and its delivery apparatus may have significantly different ferromagnetic properties.ConclusionIn case of inadvertent deployment of the sheath, a delay of 6-8 weeks before MRI is recommended as a conservative approach to ensure tissue ingrowth and to minimize the chance of harm to the patient. In the case of metallic clips used for breast biopsy, caution is warranted when a portion of the device unintended for placement is introduced into the breast.

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