Integration of 64-detector lower extremity CT angiography into whole-body trauma imaging: feasibility and early experience.

PURPOSE: To evaluate the image quality and clinical utility of a polytrauma computed tomographic (CT) protocol that integrates lower extremity CT angiography into multiphasic whole-body trauma CT by utilizing 64-detector CT and a single contrast material bolus.

MATERIALS AND METHODS: This retrospective study was institutional review board approved and HIPAA compliant. Informed consent was waived. All patients who underwent CT angiography of the lower extremities integrated with multiphasic torso CT for trauma between May 2005 and September 2009 were included. Two hundred eighty-four patients met the inclusion criteria. The mechanism of trauma was blunt injury in 228 (80.3%) of 284 patients and penetrating in 56 (19.7%) of 284 patients. CT angiography encompassed the joints proximal and distal to the injured region, with scan delay fixed at 25 seconds. Two radiologists retrospectively reviewed all the extremity CT angiograms, noting the presence of vascular injury, and measured the attenuation in the lower extremity arteries. Arterial attenuation, in Hounsfield units, was measured at multiple vascular divisions, and CT angiographic results were compared with clinical outcome, and if available, repeat lower extremity CT angiographic, conventional angiographic, or surgical findings. Sensitivity and specificity with 95% confidence intervals were calculated.

RESULTS: Sixty-three arterial injuries were identified in 44 (15.5%) of 284 patients as follows: occlusion (n = 37), narrowing (n = 9), active extravasation (n = 14), pseudoaneurysm (n= 2), and arteriovenous fistula (n = 1). Three patients underwent conventional angiography after CT angiography. Seven patients underwent surgical therapy with all CT angiographic findings confirmed. There were no injuries subsequently identified in the subgroup with a negative result at CT angiography. Of the 864 vascular divisions in which attenuation was measured, 69 (8%) of 864 had a mean attenuation less than 150 HU.

CONCLUSION: Integration of lower extremity CT angiography into multiphasic whole-body trauma imaging is feasible, helps detect clinically relevant vascular injuries, and results in diagnostic image quality in the majority of patients.