Impact of Photon-Counting CT Acquisition Modes on Coronary Stenosis Assessment and Radiation Dose: A Phantom and Clinical Evaluation.

INTRODUCTION Photon-counting detector computed tomography (PCD-CT) offers high spatial resolution and dose-efficient coronary CT angiography (cCTA), but protocol selection, especially optimal acquisition mode, requires balancing spacial resolution, temporal robustness and radiation exposure. This study evaluated various PCD-CT acquisition modes in terms of image quality, blooming, stenosis grading, diagnostic accuracy, and radiation dose using phantom and clinical cCTA.

Methods

First-generation dual-source PCD-CT was used with four acquisition modes: high-pitch spiral with prospective ECG-gating (Flash), Sequence, Spiral, and retrospective ultra-high-resolution (UHR) spiral mode. Phantom experiments used six 3D-printed coronary artery models with stenoses ranging from 21% to 73%. In a retrospective clinical study, 41 cCTA examinations were analyzed. Qualitative and quantitative image assessments used invasive coronary angiography as reference standard for diagnostic accuracy. Patient characteristics and radiation doses were recorded.

Results

UHR demonstrated the highest image quality and the lowest quantitative blooming in phantom and clinical data (clinical image quality score: UHR 4.12 ± 0.99 vs. Flash 3.00 ± 0.86; p = 0.002). Diagnostic accuracy varied across protocols for detecting ≥50% and ≥70% stenoses was high across all modes (e.g., Flash: 76.5% each; Sequence: 100% and 57.1%; UHR: 64.7% and 82.4%). Radiation dose was highest in UHR (26.44 ± 9.76 mSv) compared with Sequence (13.65 ± 8.86 mSv) and Flash (1.40 ± 0.32 mSv); all p ≤ 0.011.

Conclusion

While UHR acquisition provides highest image quality in PCD-CT cCTA, lower-dose acquisition modes achieve comparable diagnostic accuracy for coronary stenosis detection. Protocol selection should therefore be individualized, and prospective controlled studies are required.