Coronary Computed Tomographic Angiography at 80 kVp and Knowledge-Based Iterative Model Reconstruction Is Non-Inferior to that at 100 kVp with Iterative Reconstruction

Abstract

The aims of this study were to compare the image noise and quality of coronary computed tomographic angiography (CCTA) at 80 kVp with knowledge-based iterative model reconstruction (IMR) to those of CCTA at 100 kVp with hybrid iterative reconstruction (IR), and to evaluate the feasibility of a low-dose radiation protocol with IMR. Thirty subjects who underwent prospective electrocardiogram-gating CCTA at 80 kVp, 150 mAs, and IMR (Group A), and 30 subjects with 100 kVp, 150 mAs, and hybrid IR (Group B) were retrospectively enrolled after sample-size calculation. A BMI of less than 25 kg/m2 was required for inclusion. The attenuation value and image noise of CCTA were measured and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated at the proximal right coronary artery and left main coronary artery. The image noise was analyzed using a non-inferiority test. The CCTA images were qualitatively evaluated using a four-point scale. The radiation dose was significantly lower in Group A than Group B (0.69 ± 0.08 mSv vs. 1.39 ± 0.15 mSv, p < 0.001). The attenuation values were higher in Group A than Group B (p < 0.001). The SNR and CNR in Group A were higher than those of Group B. The image noise of Group A was non-inferior to that of Group B. Qualitative image quality of Group A was better than that of Group B (3.6 vs. 3.4, p = 0.017). CCTA at 80 kVp with IMR could reduce the radiation dose by about 50%, with non-inferior image noise and image quality than those of CCTA at 100 kVp with hybrid IR.

Comparing feasibility of low-tube-voltage protocol with low-iodine-concentration contrast and high-tube-voltage protocol with high-iodine-concentration contrast in coronary computed tomography angiography

“…Additionally, the low tube voltage CCTA protocol with low-iodine-concentration CM showed non-inferiority in subjective IQ. These results are in concordance with previous studies showing the feasibility of 80 kVp CCTA with iterative reconstruction [ 20 – 22 ]. We suggest that both the amount of iodine administered and radiation dose could be reduced with appropriate IQ, thereby reducing the adverse effects of CM and radiation exposure.…”

Non-inferior low-dose coronary computed tomography angiography image quality with knowledge-based iterative model reconstruction for overweight patients

“…In this study, the mean noise of CCTA differed between low and high BMI groups; however, the absolute difference was 3.2. The mean noise levels were less than 30, and the SNRs or CNRs of RCA or LM were higher than 15 in both groups, which was not lower than those reported in previous studies [11, 15]. On visual assessment, the qualitative image quality of CCTA with a fixed tube current was not significantly compromised in overweight patients as compared with non-overweight patients.…”

“…Last, we did not perform a phantom study for spatial resolution assessment of our CT system. We focused on clinically evaluating the quantitative and qualitative image quality of CCTA with low radiation dose, based on previous reports [12, 15]. Future studies should include such a phantom study to validate our findings.…”

“…In previous studies, we evaluated the feasibility of lowering tube voltage for CCTA in non-overweight patients, with BMI < 25 kg/m 2 , and showed that IMR reduced image noise in CCTA to 56–67%, as compared with FBP techniques [12, 15]. Oda et al [13] reported that CCTA with 100 kVp and model-based type IR could improve qualitative and quantitative image quality; however, they used 100–300 mAs and the range of final radiation dosage varied from 0.9 mSv to 2.6 mSv, although they used the same tube voltage.…”

“…Two radiologists with 10 and more than 20 years of experience in cardiac CT, who were blinded to the patient’s medical records, independently performed qualitative assessment of the image quality of CCTA reconstructed with IMR in both groups A and B. They used a 4-point grading system at the four main coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery) as follows [2,15].…”