Incidence of Adverse Events Related to Ballistic Fragments in Patients Undergoing MRI at a Large Urban Health System: Implications for MR Safety Screening.

Background: Patients with retained ballistic fragments commonly require MRI. Very few studies have reported MRI-related adverse events in patients with retained bullet or shrapnel fragments. Current ACR recommendations suggest caution when scanning patients with retained fragments but offer limited concrete guidance to assist MRI personnel with safety determinations.

Purpose: To assess the incidence of retained bullet or shrapnel fragments in patients undergoing MRI and of associated adverse events, in the context of an existing screening policy.

Material and methods: The Montage search feature of the PS360 reporting system for radiological examinations was used to identify, for the years 2010-2023, all patients who underwent radiographic examinations demonstrating retained bullet or shrapnel fragments, who underwent a subsequent MRI examination. Medical record review was used to assess the occurrence of adverse events related to the MRI examination.

Results: In all, 220 patients with evidence of a retained bullet or shrapnel fragment who underwent subsequent MRI were identified from 6,143 positive radiographs. Four of 220 patients (1.8%) reported transient localized burning or discomfort during the MRI examination. In each of the four patients, the retained bullet or shrapnel fragments were in the superficial soft tissues. No medical treatment was required, and no serious adverse events or persistent symptoms were reported.

Conclusion: There is a low incidence of adverse events in patients with known bullet or shrapnel fragments undergoing MRI in the context of the local screening policy. An effective screening paradigm likely plays a role in minimizing adverse events.