Low kilovolt “prospective ECG-triggering” vs. “retrospective ECG-gating” coronary CTA: comparison of image quality and radiation dose

To compare image quality and radiation doses of low kilovolt (kV) “prospective ECG-triggering” (PT) and standard “retrospective ECG-gating” (RG) coronary computed tomography (CT) angiography. A total of 101 consecutive patients (76 males, 25 females; mean age: 55.44 ± 8.28 years) with low-to-intermediate risk status for coronary artery disease and with a body mass index (BMI) of <30 kg/m² were prospectively included in the study. The images were acquired with a 64-detector (128-slice) CT using the tube current modulation technique. The PT CT technique (100 kV, heart rate [HR]<70) was applied in 59 patients, while the RG CT technique (120 kV, HR≥70-90) was applied in 42 patients. The study was approved by the ethics committee. All patients provided informed written consent.  No significant difference was found between age, sex and BMI of both groups (p > 0.05). The mean image quality score was 2.87 ± 0.25 for the low kV PT CT technique and 2.73 ± 0.31 for the RG CT technique, which was statistically significant (p < 0.05). No statistically significant difference was found between groups for signal-noise and contrast-noise ratios (p > 0.05). The mean effective dose was 1.43 ± 0.3 mSv for low kV PT CT technique and 8.20±2.36 mSv for the RG CT technique (p < 0.001). In the low kV PT CT technique, the radiation dose is significantly reduced without loss of image quality. This technique can reliably be used in patients with BMI<30 kg/m² and HR less than 70 bpm.