Acquisition time, radiation dose, subjective and objective image quality of dual-source CT scanners in acute pulmonary embolism: a comparative study

Objectives To compare the scan acquisition time, radiation dose, subjective and objective image quality of two dual-source CT scanners (DSCT) for detection of acute pulmonary embolism. Methods Two hundred twenty-one scans performed on the 2nd-generation DSCT and 354 scans on the 3rd-generation DSCT were included in this large retrospective study. In a randomized blinded design, two radiologists independently reviewed the scans using a 5-point Likert scale. Radiation dose and objective image quality parameters were calculated. Results Mean acquisition time was significantly lower in the 3rd-generation DSCT (2.81 s +/- 0.1 in comparison with 9.7 s +/- 0.15 [mean +/- SD] respectively; p < 0.0001) with the 3rd generation 3.4 times faster. The mean subjective image quality score was 4.33/5 and 4/5 for the 3rd- and 2nd-generation DSCT respectively (p < 0.0001) with strong interobserver reliability agreement. DLP, CTDIvol, and ED were significantly lower in the 3rd than the 2nd generation (175.6 +/- 63.7 mGy cm; 5.3 +/- 1.9 mGy and 2.8 +/- 1.2 mSv in comparison with 266 +/- 255 mGy.cm; 7.8 +/- 2.2 mGy and 3.8 +/- 4.3 mSv). Noise was significantly lower in the 3rd generation (p < 0.01). Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM), a dose-insensitive index for CNR, were significantly higher in the 3rd-generation DSCT (33.5 +/- 23.4; 29.0 +/- 21.3 and 543.7 +/- 1037 in comparison with 23.4 +/- 17.7; 19.4 +/- 16.0 and 170.5 +/- 284.3). Conclusion Objective and subjective image quality are significantly higher on the 3rd-generation DSCT with significantly lower mean acquisition time and radiation dose.