| Summary: | Coronary computed tomography angiography (CTA) is increasingly being used for evaluation of coronary artery disease (CAD), but Radiation exposure still a major limitation of its use.We hypothesized that the high pitch spiral (FLASH) is superior to prospective (step and shoot (SAS)) ECG gating scan protocol, and associated with a low radiation exposure. The purpose of our study is to compare image quality and radiation exposure in a two group of patients undergoing CTA using a 256-slice dual source helical CT scanner with FLASH or SAS protocols.We randomized 162 patients referred for coronary CTA for either FLASH or SAS scanning protocols, subjective Image quality was graded based on a 4-point grading system (1: non diagnostic, 2: adequate, 3: good, 4: excellent). While Objective image quality was assessed using image signal, noise, and signal-to-noise ratio (SNR). The effective radiation dose was also estimated.The clinical and demographic characteristics of the patients in both groups were similar. We found that subjective image quality obtained with FLASH was superior to SAS (3.35 ± 0.6 vs. 2.82 ± 0.61 mSv; p < 0.001), image noise was not statistically different (25.0 ± 6.13 24.0 ± 6.8, p = 0.10), while the signal and SNR was significantly higher with FLASH Compared to SAS (469 ± 116 vs. 397 ± 106. P = < 0.001) and (21.9 ± 8.7 vs. 16.6 ± 7.7 mSv; p < 0.001) respectively. Radiation exposure was 62% lower in FLASH compared to SAS protocol, (1.9 ± 0.4 mSv vs. 5.12 ± 1.8 mSv; p < 0.001). Use of 256-slice CTA performed with FLASH protocol has better objective and subjective image quality, lower radiation exposure when compared with the use of prospective ECG gating.
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