Stent appearance in a novel silicon-based photon-counting CT prototype: ex vivo phantom study in head-to-head comparison with conventional energy-integrating CT
Emma Verelst, Nico Buls, Johan De Mey, Koenraad Nieboer, Frans Vandenbergh, Dominic J. Crotty, Paul Deak, Albert Sundvall, Staffan Holmin, Aron De Smet, Steven Provyn, Gert Van Gompel
Abstract
Abstract Background In this study, stent appearance in a novel silicon-based photon-counting computed tomography (Si-PCCT) prototype was compared with a conventional energy-integrating detector CT (EIDCT) system. Methods An ex vivo phantom was created, consisting of a 2% agar-water mixture, in which human-resected and stented arteries were individually embedded. Using similar technique parameters, helical scan data was acquired using a novel prototype Si-PCCT and a conventional EIDCT system at a volumetric CT dose index (CTDI vol ) of 9 mGy. Reconstructions were made at 50 2 and 150 2 mm 2 field-of-views (FOVs) using a bone kernel and adaptive statistical iterative reconstruction with 0% blending. Using a 5-point Likert scale, reader evaluations were performed on stent appearance, blooming and inter-stent visibility. Quantitative image analysis was performed on stent diameter accuracy, blooming and inter-stent distinction. Qualitative and quantitative differences between Si-PCCT and EIDCT systems were tested with a Wilcoxon signed-rank test and a paired samples t -test, respectively. Inter- and intra-reader agreement was assessed using the intraclass correlation coefficient (ICC). Results Qualitatively, Si-PCCT images were rated higher than EIDCT images at 150-mm FOV, based on stent appearance ( p = 0.026) and blooming ( p = 0.015), with a moderate inter- (ICC = 0.50) and intra-reader (ICC = 0.60) agreement. Quantitatively, Si-PCCT yielded more accurate diameter measurements ( p = 0.001), reduced blooming ( p < 0.001) and improved inter-stent distinction ( p < 0.001). Similar trends were observed for the images reconstructed at 50-mm FOV. Conclusions When compared to EIDCT, the improved spatial resolution of Si-PCCT yields enhanced stent appearance, more accurate diameter measurements, reduced blooming and improved inter-stent distinction. Key points • This study evaluated stent appearance in a novel silicon-based photon-counting computed tomography (Si-PCCT) prototype. • Compared to standard CT, Si-PCCT resulted in more accurate stent diameter measurements. • Si-PCCT also reduced blooming artefacts and improved inter-stent visibility.