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

Background: 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. Materials and Methods: 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.  Results: 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). Conclusion: 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.