Image quality in coronary computed tomography angiography: influence of adaptive statistical iterative reconstruction at various radiation dose levels

Abstract

Background Computed tomography (CT) technology is rapidly evolving and software solution developed to optimize image quality and/or lower radiation dose. Purpose To investigate the influence of adaptive statistical iterative reconstruction (ASIR) at different radiation doses in coronary CT angiography (CCTA) in detailed image quality. Material and Methods A total of 160 CCTA were reconstructed as follows: 55 scans with filtered back projection (FBP) (650 mA), 51 scans (455 mA) with 30% ASIR (ASIR30), and 54 scans (295 mA) with 60% ASIR (ASIR60). For each reconstruction, subjective image quality was assessed by five independent certified cardiologists using a visual grading analysis (VGA) with five predefined image quality criteria consisting of a 5-point scale. Objective measures were contrast, noise, and contrast-to-noise ratio (CNR). Results The CTDI resulted in 10.3 mGy, 7.4 mGy, and 4.6 mGy for FBP, ASIR30, and ASIR60, respectively. Homogeneity of the left ventricular lumen was the sole aspect in which reconstruction algorithms differed with a decreasing effect for ASIR60 compared to FBP (estimated odds ratio [OR] = 0.49 [95% confidence interval (CI) = 0.32-0.76; P = 0.001]). Decreased sharpness and spatial- and low-contrast resolutions were observed when using ASIR instead of FBP, but differences were not statistically significant. Concerning objective measurements, noise increased significantly for ASIR30 (OR = 1.08; 95% CI = 1.02-1.14; P = 0.006) and ASIR60 (OR = 1.06; 95% CI = 1.01-1.12; P = 0.034) compared to FBP. Conclusion ASIR significantly decreased the subjectively assessed homogeneity of the left ventricular lumen and increased the objectively measured noise compared to FBP. Considering these results, ASIR at a reduced radiation dose should be implemented with caution.

Potential increase in radiation‐induced DNA double‐strand breaks with higher doses of iodine contrast during coronary CT angiography

“…Not only the delivered radiation‐ and iodine dose but also the irradiated blood volume has an impact on the number of γH2AX foci in a blood sample. The mean CTDI vol (10.6 ± 5.6 mGy) and iodine dose (24.7 ± 4.9 gI) of this study were comparable to recently published radiation doses (4.6–10.3 mGy) and iodine doses (25.3 gI) in CCTA 29 . The mean exposed blood volume, measured in the CT images, was 683.0 ± 118.3 ml, which is approximately 13.7% of the average adult blood volume of 5000 ml 29 .…”

“…The mean CTDI vol (10.6 ± 5.6 mGy) and iodine dose (24.7 ± 4.9 gI) of this study were comparable to recently published radiation doses (4.6–10.3 mGy) and iodine doses (25.3 gI) in CCTA 29 . The mean exposed blood volume, measured in the CT images, was 683.0 ± 118.3 ml, which is approximately 13.7% of the average adult blood volume of 5000 ml 29 . In the blood circulation, the irradiated blood volume is mixed with non‐irradiated blood, "diluting" the observable number of γH2AX foci.…”

“… 29 The mean exposed blood volume, measured in the CT images, was 683.0 ± 118.3 ml, which is approximately 13.7% of the average adult blood volume of 5000 ml. 29 In the blood circulation, the irradiated blood volume is mixed with non‐irradiated blood, "diluting" the observable number of γH2AX foci.…”

Incremental Image Noise Reduction in Coronary CT Angiography Using a Deep Learning-Based Technique with Iterative Reconstruction

“…As with our deep learning based denoising software, iterative reconstruction algorithms, which are an alternative to traditional FBP reconstructions, have been proven by various studies to improve objective and subjective image quality. However, few techniques have been shown to improve the diagnostic accuracy more than FBP, at the same radiation dose (34)(35)(36)(37)(38).…”

“…As with our deep learning based denoising software, iterative reconstruction algorithms, which are an alternative to traditional FBP reconstructions, have been proven by various studies to improve objective and subjective image quality. However, few techniques have been shown to improve the diagnostic accuracy more than FBP, at the same radiation dose ( 34 35 36 37 38 ). Instead, most studies have demonstrated that low radiation dose techniques enabled by an iterative reconstruction algorithm while maintaining diagnostic accuracy ( 39 40 41 ).…”