Ultra-high-pitch photon-counting computed tomography (PCCT) versus ultra-high-pitch dual-source computed tomography (DSCT) for coronary artery disease evaluation in transcatheter aortic valve implantation (TAVI) patients

Rationale and objectives To compare radiation dose and image quality of coronary artery reconstructions obtained from non–coronary-dedicated transcatheter aortic valve implantation (TAVI) planning CT scans using ultra-high-pitch photon-counting CT (PCCT) and ultra-high-pitch energy-integrating detector dual-source CT (EID-DSCT; hereafter referred to as DSCT), including assessment of the feasibility of coronary artery evaluation according to the Coronary Artery Disease Reporting and Data System (CAD-RADS). Materials and methods Retrospective study on consecutive patients with aortic valve stenosis (AS) undergoing contrast-enhanced TAVI planning CT, either PCCT or DSCT between August 2021 and June 2023. CT dose index (CTDI) and dose length product (DLP) were used to calculate the effective radiation dose (eRD). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated using standardized region-of-interest (ROI) analysis. Coronary arteries were evaluated by three independent radiologists using 5-point Likert scales followed by a classification according to the CAD-RADS system. Results 187 patients (83 female, median age 82, IQR: 76–84) underwent 190 CT-examinations, 103 PCCT (54.2%) and 87 (45.8%) DSCT. Three patients underwent both PCCT and DSCT for clinical reasons. Mean CTDI and DLP were significantly lower in PCCT compared to DSCT (21.9 vs. 52.8 and 607.9 vs. 906.8, respectively; both p < 0.001), with a correspondingly lower mean effective radiation dose (eRD) in PCCT compared to DSCT (10.3 ± 5.4 mSv vs. 15.4 ± 5.6 mSv, p < 0.001). While both SNR and CNR were lower in PCCT than in DSCT (SNR: 35.28 ± 11.63 in PCCT vs. 45.6 ± 16.3 in DSCT, p < 0.001; CNR: 49.25 ± 13.31 in PCCT vs. 57.42 v ± 22.55 in DSCT, p = 0.004), PCCT outperformed DSCT in every one of the eleven visual image categories. Overall image quality was rated as good or excellent in 71.8% (74/103) of PCCT vs. 19.5% (17/87) of DSCT scans. Coronary reconstructions were rated as good or excellent in 72.8% (75/103) of PCCT vs. 20.7% of DSCT datasets. CAD-RADS [1–5] rating was possible in 68.9% (71/103) of PCCT vs. 39.1% (34/87) of DSCT datasets. Conclusion Photon-counting computed tomography (PCCT) allows for significantly improved assessability of the coronary arteries in TAVI planning CT compared with dual-source CT (DSCT), while achieving a substantially lower radiation dose.