Prospective, multireader evaluation of image quality and vascular delineation of multislice CT angiography of the brain.

The aim of this prospective, multireader trial was to investigate image quality and vascular delineation of cranial multislice CT angiography (MSCTA) to identify strengths and weaknesses of the method. Sixty consecutive patients underwent standardized cranial MSCTA. The mean estimated effective dose was 0.96+/-0.11 mSv. Three masked readers independently graded image quality parameters and vascular delineation on a 5-point scale. Vascular attenuation values and dose-length products were assessed quantitatively. Quantitative parameters were evaluated with a proportional odds regression model with bootstrapped standard errors to adjust the relevant standard errors for correlation within subjects and across readers. The non-parametric Wilcoxon sign-rank test was applied for quantitative measurements. Good to excellent ratings were observed regarding image quality parameters and vascular delineation. The delineation of veins was rated higher than that of arteries (OR 2.00). Smaller arterial segments were rated significantly less favorably than larger segments (OR up to 26.98). Moreover, the cavernous sinus, the C2 segment of the ICA and the communicating arteries demonstrated lower scores. Attenuation values were >240 HU and vessel-to-parenchyma ratios >7 in all vessels. Cranial MSCTA achieved high ratings regarding image quality and vascular delineation. Relative weaknesses were found in small arterial subsegments and in vessels in close topographical proximity to bone.