Radiology: Integrated lower extremity CTA feasible, effective in trauma cases

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Posterior volume-rendered image shows pseudoaneurysm (arrow) adjacent to fractures and bone fragment (arrowhead). Source: Radiology.

Integrating lower extremity CT angiography (CTA) into a multiphasic whole-body CT can help detect clinically relevant vascular injuries, decrease time to diagnosis and reduce the contrast load, according to a study published online Sept. 20 in Radiology.

CTA applications have soared in recent years, particularly in the trauma setting, with many multitrauma patients requiring multiple imaging studies, according to Bryan. R. Foster, MD, assistant professor of radiology, Oregon Health & Science University in Portland, Ore., and colleagues. Many hospitals have combined torso CT and extremity CTA into a single study with one contrast bolus. However, the image quality and diagnostic accuracy of the protocol have not been verified, wrote the authors.

The researchers completed a retrospective study to assess the image quality and clinical utility of a polytrauma protocol with integrated lower extremity CTA using a 64-slice CT system and single contrast bolus.

The study focused on 284 trauma patients who underwent CTA of the lower extremities between May 2005 and September 2009. CTA results were compared with the clinical outcome and, when available, repeat CTA studies, conventional angiographic or surgical findings.

The researchers reported injuries in 15.5 percent of patients, with a total of 63 arterial injuries observed. Diagnoses included: occlusion, narrowing, active extravasation, pseudoaneurysm and occlusion with arteriovenous fistula. Seven of these patients underwent surgeries, and CTA-detected injuries were confirmed in six of the seven patients.

Foster et al also noted that all of the 218 patients with no CTA evidence of arterial injury were successfully treated conservatively. A follow-up chart review indicated no evidence of missed injury.

Twenty-two patients had non-diagnostic CTA studies, which were attributed to either poor timing or an outrun bolus. The authors offered several factors that may have contributed to suboptimal arterial opacification, including native inflow disease, hypotension, hypoperfusion and elevated systemic vascular resistance.

“The protocols described combine the necessary lower extremity CT angiography and torso CT into a single examination, saving precious time in this population and at the same time avoiding dual injections of contrast material,” wrote Foster et al.  They emphasized that the protocol identified vascular injuries requiring surgical management and provided adequate image quality in most cases.