PurposeCoronary artery calcification (CAC) is an important indicator of coronary disease. Accurate volume quantification of CAC is challenging using computed tomography (CT) due to calcium blooming, which is a consequence of limited spatial resolution. Ex vivo coronary specimens were scanned on an ultra-high-resolution (UHR) clinical photon-counting detector (PCD) CT scanner, and the accuracy of CAC volume estimation was compared with a state-of-the-art conventional energy-integrating detector (EID) CT, a previous-generation investigational PCD-CT, and micro-CT.ApproachCAC specimens (n = 13) were scanned on EID-CT and PCD-CT using matched parameters (120 kV, 9.3 mGy CTDIvol). EID-CT images were reconstructed using our institutional routine clinical protocol for CAC quantification. UHR PCD-CT data were reconstructed using a sharper kernel. An image-based denoising algorithm was applied to the PCD-CT images to achieve similar noise levels as EID-CT. Micro-CT images served as the volume reference standard. Calcification images were segmented, and their volume estimates were compared. The CT data were further compared with previous work using an investigational PCD-CT.ResultsCompared with micro-CT, CT volume estimates had a mean absolute percent error of 24.1 % ± 25.6 % for clinical PCD-CT, 60.1 % ± 48.2 % for EID-CT, and 51.1 % ± 41.7 % for previous-generation PCD-CT. Clinical PCD-CT absolute percent error was significantly (p < 0.01) lower than both EID-CT and previous generation PCD-CT. The mean calcification CT number and contrast-to-noise ratio were both significantly (p < 0.01) higher in clinical PCD-CT relative to EID-CT.ConclusionsUHR clinical PCD-CT showed reduced calcium blooming artifacts and further enabled improved accuracy of CAC quantification beyond that of conventional EID-CT and previous generation PCD-CT systems.
Coronary CT Angiography (cCTA) is commonly used to detect and quantify luminal stenoses in patients with coronary artery disease (CAD). However, its use is limited in patients with heavy coronary calcifications due to calcium blooming, which is caused by insufficient spatial resolution. This study evaluated the ability of a photon-counting-detector (PCD) CT in quantifying of luminal stenosis in the presence of heavy calcifications relative to an energy-integrating-detector (EID) CT. The phantom results indicate that with PCD-CT, luminal stenoses that were previously considered non-assessable due to the presence of heavily-calcified plaques can be assessed using cCTA.
Coronary artery calcification is an important indicator of coronary disease. Accurate volume quantification of coronary calcification using computed tomography (CT) is challenging due to calcium blooming. In this study, ex-vivo coronary specimens were scanned on an investigational photon-counting detector (PCD) CT scanner and the estimated coronary calcification volume were compared with a conventional energy-integrating detector (EID) CT. An image-based denoising algorithm was applied to the PCD-CT images to achieve similar noise levels as EID-CT. Calcifications were segmented to estimate the volume, with micro-CT images of the same calcifications serving as reference. PCD-CT images showed reduced calcium blooming artifacts.
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