Spectral Photon-Counting Detector Coronary CTA With Reduced Radiation and Contrast Medium Dose in Inflammation-Associated Coronary Artery Disease: A Prospective Study

<b>BACKGROUND</b>. Patients with inflammation-associated coronary artery disease (CAD) may exhibit rapid progression and require regular coronary imaging. <b>OBJECTIVE</b>. The purpose of this article was to evaluate the diagnostic performance of spectral photon-counting detector (PCD) coronary CTA with reduced radiation and contrast medium dose for detecting coronary stenosis and in-stent restenosis in patients with inflammation-associated CAD. <b>METHODS</b>. This prospective study enrolled patients with inflammation-associated CAD from January 2022 to March 2024. Participants underwent spectral PCD coronary CTA using prospectively ECG-triggered sequential acquisition and an individualized low-dose contrast medium protocol. Images were reconstructed with virtual monoenergetic imaging (VMI) at 55 keV and polychromatic (T3D) imaging using matching parameters, including 0.4-mm slice thickness. Two readers independently assessed subjective (5-point Likert scales) and objective image quality measures; readers also assessed images for obstructive stenosis and in-stent restenosis (both ≥ 50%) in patients with invasive coronary angiography (ICA) available as a reference. <b>RESULTS</b>. The analysis included 63 patients (mean age, 50.4 ± 11.5 [SD] years; 45 women, 18 men). Median contrast medium volume was 28.0 mL. Median DLP was 165.0 mGy ∙ cm. Images from 55-keV VMI, compared with those from T3D imaging, showed better (<i>p</i> < .05) overall image quality, diagnostic confidence, SNR, and CNR in all three assessed vessels (e.g., right coronary artery for reader 1: overall image quality of 4.5 vs 4.1 and CNR of 12.1 vs 9.9). Diagnostic performance using ICA as the reference was evaluated in 40 patients with 132 lesions and 75 stents. Images from 55-keV VMI, compared with those from T3D imaging, showed higher (<i>p</i> < .05) per-lesion accuracy for obstructive stenosis (reader 1: 96.2% vs 84.1%; reader 2: 97.0% vs 86.4%); these differences in accuracy were also observed for both readers for noncalcified and partly calcified plaques, lesions in mid and distal segments, and patients with a BMI of 24 and greater. Images from 55-keV VMI and T3D imaging showed no significant difference (<i>p</i> > .05) in accuracy for in-stent restenosis (reader 1: 97.3% vs 96.0%; reader 2: 96.0% vs 94.7%). <b>CONCLUSION</b>. Spectral PCD coronary CTA, performed using low radiation and contrast medium dose and reconstructed using 55-keV VMI, showed excellent diagnostic accuracy in detecting obstructive stenosis and in-stent restenosis in patients with inflammation-associated CAD. <b>CLINICAL IMPACT</b>. The proposed protocol could be used to guide clinical decision-making in inflammation-associated CAD.