Evaluation of coronary plaques and stents with conventional and photon-counting ct: Benefits of highresolution photon-counting ct

Purpose: To compare the performance of energy-integrating detector (EID) CT, photon-counting detector CT (PCCT), and highresolution PCCT (HR-PCCT) for the visualization of coronary plaques and reduction of stent artifacts in a phantom model. Materials and Methods: An investigational scanner with EID and PCCT subsystems was used to image a coronary artery phantom containing cylindrical probes simulating different plaque compositions. The phantom was imaged with and without coronary stents using both subsystems. Images were reconstructed with a clinical cardiac kernel and an additional HR-PCCT kernel. Regions of interest were drawn around probes and evaluated for in-plane diameter and a qualitative comparison by expert readers. A linear mixed-effects model was used to compare the diameter results, and a Shrout-Fleiss intraclass correlation coefficient was used to assess consistency in the reader study. Results: Comparing in-plane diameter to the physical dimension for nonstented and stented phantoms, measurements of the HRPCCT images were more accurate (nonstented: 4.4% 6 1.1 [standard deviation], stented: 9.4% 6 4.6) than EID (nonstented: 15.5% 6 4.0, stented: 19.5% 6 5.8) and PCCT (nonstented: 19.4% 6 2.5, stented: 18.3% 6 4.4). Our analysis of variance found diameter measurements to be different across image groups for both nonstented and stented cases (P, 001). HR-PCCT showed less change on average in percent stenosis due to the addition of a stent (-5.5%) than either EID (190.5%) or PCCT (1313%). For both nonstented and stented phantoms, observers rated the HR-PCCT images as having higher plaque conspicuity and as being the image type that was least impacted by stent artifacts, with a high level of agreement (interclass correlation coefficient=0.85). Conclusion: Despite increased noise, HR-PCCT images were able to better visualize coronary plaques and reduce stent artifacts compared with EID or PCCT reconstructions. Abbreviations CNR=contrast-to-noise ratio, EID=energy-integrating detector CT, HR-PCCT=high-resolution PCCT, PCCT=photon-counting CT, QRM=Quality Assurance in Radiology and Medicine, ROI=region of interest Summary High-resolution photon-counting CT images enable improved visualization and quantitative assessment of coronary plaques and stents as assessed in a phantom model. Key Points n Photon-counting CT (PCCT) is a developing technology that can improve the visualization of coronary plaques and stents by using high-resolution imaging techniques. n High-resolution PCCT (HR-PCCT) images enabled more accurate measurements of coronary diameter than either photon-counting or energy-integrating CT with and without stents. n Physician experts in cardiac CT found HR-PCCT images to offer better plaque conspicuity and less blooming artifact than either photon-counting or energy-integrating CT.