Dose performance and image quality: dual source CT versus single source CT in cardiac CT angiography

To evaluate dose performance and image quality of 64-slice dual source CT (DSCT) in comparison to 64-slice single source CT (SSCT) in cardiac CT angiography (CTA).

100 patients examined by DSCT and 60 patients scanned by SSCT were included in this study. Objective indices such as image noise, contrast-to-noise ratio and signal-to-noise ratio were analyzed. Subjective image quality was assessed by two cardiovascular radiologists in consensus using a four-point scale (1=excellent to 4=not acceptable). Estimation of effective dose was performed on the basis of dose length product (DLP).

At low heart rates (<70 bpm), image quality of SSCT was equivalent to that of DSCT (P>0.05), but, at high heart rates (>70 bpm), DSCT provided robust image quality (P<0.05). The average effective dose of SSCT was 9.3+/-0.9 mSv at low heart rates (<70 bpm) while, the average estimated effective doses of DSCT were 9.1+/-1.3 mSv, 8.3+/-1.1 mSv, 7.9+/-1.1 mSv, 6.9+/-0.7 mSv, and 5.9+/-1.3 mSv, corresponding to heart rates of 50-59 bpm, 60-69 bpm, 70-79 bpm, 80-89 bpm, and 90-100 bpm.

For cardiac CTA, both DSCT and SSCT can get good image quality at low heart rates (<70 bpm) with a similar radiation dose, but, at high heart rates (>70 bpm), DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT.