Triple rule-out acute chest pain evaluation using a 320-row-detector volume CT: a comparison of the wide-volume and helical modes.

The purpose of this study was to investigate the image quality and radiation dose of triple rule-out computed tomography (TROCT) using a 320-row-detector volume CT system to compare the wide-volume and helical modes of this CT system. Sixty-four patients with noncritical chest pain were allocated to one of 2 groups according to the type of CT examination mode used. Group 1 patients were examined using the wide-volume (non-spiral) mode and group 2 patients were examined using the 160-detector row helical mode, with the same contrast injection protocol in both methods [biphasic injection protocol; injection rate of 4 ml/s, median volume, 70 ml (range 65-100 ml)]. Attenuations of the pulmonary trunk, ascending aorta, and coronary arteries were measured in Hounsfield units; a subjective overall patient-based image quality score of 1-3 was awarded to each study. Effective doses, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Average effective dose was significantly lower in group 1 than group 2 (9.7 ± 5.1 vs. 16 ± 5.9 mSv, P < 0.001). The mean attenuation of the main pulmonary trunk was significantly higher in group 1 than group 2 (P = 0.04) and mean attenuations in other vessels were not significant different. SNR and CNR were not significantly different between the groups. The proportion of diagnostic image qualities for chest CT angiography (CTA) was similar between the groups (93.5 vs. 93.9 %). In coronary CTA, group 1 showed a higher proportion of diagnostic image qualities than group 2 (100 vs. 87.9 %). The use of wide-volume mode of 320-detector CT reduces the overall effective radiation dose and results in similar attenuation and image quality for TROCT as compared with the helical mode.