Preliminary examination to determine the suitable contrast material injection protocol for CT angiography of the pelvis and lower extremities with a multidetector row helical scanner

Abstract

The aim of this study was to determine the best of three protocols for the depiction of arteries in the pelvis and lower extremities by computed tomographic angiography (CTA) with a multidetector row helical scanner. CTA was performed in five asymptomatic volunteers using a four-channel multidetector row helical scanner. Low-osmolar iodinated contrast material was injected at the flow rate of 3 ml/s using three protocols: 100 ml of 300 mg I/ml, 150 ml of 300 mg I/ml, and 100 ml of 350 mg I/ml. The CT number of opacified blood was measured at six levels. Three doctors independently assessed the degree of depiction of arteries on CTA images without knowing the protocol using a 3-point scale. CT numbers at the level of the popliteal artery on the protocol of 150 ml of 300 mg I/ml were significantly greater than the others. The mean score for the depiction of trifurcation on the protocol of 150 ml of 300 mg I/ml was significantly greater than those in the others. The protocol of 150 ml of 300 mg I/ml was the best for depicting arteries in the pelvis and lower extremities by CTA.