Ballistic Injury Imaging: The Basics

Purpose As of 2007, there were estimated to be at least 750 million firearms in worldwide circulation, of which 650 million of them were owned by civilians (Weiss et al. in Severe lead toxicity attributed to bullet fragments retained in soft tissue. BMJ Case Reports, 2017 ). Of these, approximately 270 million are in the United States, equating to 84 guns per 100 Americans [based on 2016 population statistics (assuming the number of firearms remained stable over the intervening 9 years)] and resulting in 84 997 nonfatal injuries and 36 252 fatalities in the United States in 2015. With statistics like these, it stands to reason that victims of gunshot wounds (GSW) will be imaged by most radiologists at least once in their careers. This article seeks to increase radiologists’ knowledge of the pathophysiology of GSW and will review the mechanism of ballistic injury and relate these to commonly encountered imaging findings. Important Points Ballistic injuries are a combination of the direct injury caused by the bullet along its path through the tissues and the shockwave created around that path as the bullet expends its energy. CT is the gold standard in ballistic injury assessment. MRI is not contraindicated in patients with retained ballistic fragments, but should be used with caution. The number of entry/exit wound and the number of retained ballistic fragments should be an even number, or there is a missing surface wound or a missing bullet. Retained lead in joints can result in plumbism and arthropathy. Summary As most radiologists will encounter a ballistic injury in the course of their careers, an understanding of this unique mechanism of injury and its complications will aid in both imaging interpretation and patient care.