ECG-Gated Retrospective Coronary CT Angiography With Deep Learning Reconstruction on 8-cm Detector CT Scanners: Pushing Radiation Dose Towards Prospective Acquisition on 16-cm Wide-Detector Scanners.

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Abstract

Although 16-cm wide-detector CT scanners with prospective ECG-gating enable coronary artery imaging within a single cardiac cycle at a low radiation dose, many institutions still rely on scanners with detector widths <16 cm. These scanners typically use retrospective scanning, resulting in higher radiation exposure. This study tests the feasibility of lowering the radiation dose of ECG-gated retrospective CCTA on 8-cm detector scanners to the level of prospective acquisition on 16-cm ones, using deep learning reconstruction (DLR). This study involved 83 low-dose (group A) and 62 routine-dose (group B) retrospective CCTA cases on an 8-cm detector scanner, with the low-dose protocol targeting a radiation level comparable to prospective acquisitions on 16-cm scanners. Groups Ref1 and Ref2 were used as the dose and image quality benchmarks. They consisted of prospective CCTA cases acquired on 16-cm scanners from a shared vendor, and were extracted from published studies. Specific subsets (A1/B1 and A2/B2) were selected from group A/B based on weight (55 to 75 kg) and HR (<75 bpm) to match Ref1 and Ref2. DLR was used for group A. Image quality was evaluated using signal-to-noise ratio (SNR) and subjective scoring. No significant differences in demographics were noted among Ref1/A1/B1 or Ref2/A2/B2 (all P>0.05). CTDIvol for A1 was comparable to Ref1 (median: 13.6 mGy vs. 13.2 mGy, P>0.999), whereas A2 had lower CTDIvol than Ref2 (median: 13.3 mGy vs. 16.1 mGy, P=0.018). DLR improved SNRs in group A, with higher values than Ref and B (all P<0.05). With DLR, image quality scores were comparable between groups A and B (all P>0.05). DLR can lower the radiation dose in retrospective CCTA on 8-cm detector scanners to that of prospective CCTA on 16-cm ones, with non-inferior image quality.

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