Assessment of Cross-sectional Area and Diameter of Carotid Artery Using Time-of-flight MR Angiography and CT Angiography

PURPOSE: In carotid artery stenosis, precisely assessing the vessel cross-sectional area and diameter is important because this result determines the treatment strategy for patients. The purpose of our study was to evaluate the vessel sizes of normal and stenotic carotid arteries using time-of-flight magnetic resonance angiography (TOF-MRA) and X-ray CT angiography (CTA). METHOD AND MATERIALS: The TOF-MRA and the CTA data were obtained using 3D TOF-MRA on a 1.5-T MR scanner (1.0 mm slice thickness) and dynamic contrast-enhanced multi-detector row CT (0.5 mm slice thickness). In thirty-three normal patients (20 men, 13 women, mean age of 66.9±9.0 years) and eighteen patients with carotid artery stenosis (12 men, 6 women, mean age of 74.4±6.4 years), we measured the vessel cross-sectional areas and the diameters of the internal and common carotid arteries (ICAs and CCAs) using TOF-MRA and CTA and a vessel-analytic program of the workstation. RESULTS: The mean cross-sectional areas and diameters of normal ICAs and CCAs determined using TOF-MRA were significantly smaller than those determined using CTA. The percentages of area and diameter stenoses found using TOF-MRA were 7.7 and 14.3% higher than those found using CTA. In six cases in the stenotic group, the stenotic artery showed no signal using TOF-MRA, but the CTA depicted it. CONCLUSION: In both normal and stenotic carotid arteries, TOF-MRA underestimates vessel size more than CTA does.