Diagnosing traumatic arterial injury in the extremities with CT angiography: pearls and pitfalls.

Computed tomographic (CT) angiography is a reliable and convenient imaging modality for diagnosing arterial injuries after blunt and penetrating trauma to the extremities. It is a noninvasive modality that could replace conventional arteriography as the initial diagnostic study for arterial injuries after trauma to the extremities. The technique requires scanning with multidetector helical CT after rapid intravenous injection of iodinated contrast material. The CT angiographic signs of arterial injuries in the extremities are active extravasation of contrast material, pseudoaneurysm formation, abrupt narrowing of an artery, loss of opacification of a segment of artery, and arteriovenous fistula formation. Metallic streak artifact, motion artifact, and inadequate arterial opacification may render a CT angiogram nondiagnostic. Studies have shown the sensitivity of CT angiography to be 90%-95.1% and its specificity 98.7%-100% for detecting arterial injury to the extremities after trauma.