Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Tübingen, Germany.
Diagn Interv Radiol. 2022 Jul;28(4):364-369. doi: 10.5152/dir.2022.21107.
PURPOSE The purpose of this study is to systematically evaluate the effect of tube voltage, current kernels, and monoenergetic post-processing on stent visualization. METHODS A 6 mm chrome-cobalt peripheral stent was placed in a dedicated phantom and scanned with the available tube voltage settings of a third-generation dual-source scanner in single-energy (SE) and dual-energy (DE) mode. Images were reconstructed using the latest convolution kernels and monoenergetic reconstructions (40-190 keV) for DE. The sharpness of stent struts (S), struts width (SW), contrast-to-noise-ratios (CNR), and pseudoenhancement (PE) between the vessel with and without stent were analyzed using an in-house built automatic analysis tool. Measurements were standardized through calculated z-scores. Z-scores were combined for stent (SQ), luminal (LQ), and overall depiction quality (OQ) by adding S and SW, CNR and SW and PE, and S and SW and CNR and PE. Two readers rated overall stent depiction on a 5-point Likert-scale. Agreement was calculated using linear-weighted kappa. Correlations were calculated using Spearman correlation coefficient. RESULTS Maximum values of S and CNR were 169.1 HU/pixel for [DE; 100/ Sn 150 kV; Qr59; 40 keV] and 50.0 for [SE; 70 kV; Bv36]. Minimum values of SW and PE were 2.615 mm for [DE; 80 to 90/ Sn 150 kV; Qr59; 140 to 190 keV] and 0.12 HU for [DE; 80/ Sn 150 kV; Qr36; 190 keV]. Best combined z-scores of SQ, LQ, and OQ were 4.53 for [DE; 100/ Sn 150 kV; Qr 59; 40 keV], 1.23 for [DE; 100/ Sn 150 kV; Qr59; 140 keV] and 2.95 for [DE; 90/ Sn 150 kV; Qr59; 50 keV]. Best OQ of SE was ranked third with 2.89 for [SE; 90 kV; Bv59]. Subjective agreement was excellent (kappa=0.86; P < .001) and correlated well with OQ (rs=0.94, P < .001). CONCLUSION Combining DE computed tomography (CT) acquisition with the latest kernels and monoenergetic post-processing allows for improved stent visualization as compared with SECT. The best overall results were obtained for monoenergetic reconstructions with 50 keV from DECT 90/Sn 150 kV acquisitions using kernel Qr59.
目的 本研究旨在系统评估管电压、电流核、单能量后处理对支架可视化的影响。
方法 使用第三代双源扫描仪的可用管电压设置，在专用体模中放置一个 6 毫米的铬钴外周支架，进行单能量（SE）和双能量（DE）模式扫描。使用最新的卷积核和单能量重建（40-190keV）对 DE 进行图像重建。使用内部构建的自动分析工具分析支架支柱的清晰度（S）、支柱宽度（SW）、对比噪声比（CNR）和有支架与无支架血管之间的伪增强（PE）。通过计算 z 分数对测量值进行标准化。通过将 S 和 SW、CNR 和 SW 以及 PE 和 S 和 SW、CNR 和 PE 相加，将 z 分数组合成支架（SQ）、管腔（LQ）和整体描绘质量（OQ）。两位读者使用 5 分李克特量表对整体支架描绘进行评分。使用线性加权 kappa 计算一致性。使用 Spearman 相关系数计算相关性。
结果 S 和 CNR 的最大值分别为[DE；100/Sn150kV；Qr59；40keV]的 169.1HU/pixel 和[SE；70kV；Bv36]的 50.0。SW 和 PE 的最小值分别为[DE；80 至 90/Sn150kV；Qr59；140 至 190keV]的 2.615mm 和[DE；80/Sn150kV；Qr36；190keV]的 0.12HU。SQ、LQ 和 OQ 的最佳组合 z 分数分别为[DE；100/Sn150kV；Qr59；40keV]的 4.53、[DE；100/Sn150kV；Qr59；140keV]的 1.23 和[DE；90/Sn150kV；Qr59；50keV]的 2.95。SE 的最佳 OQ 排名第三，为[SE；90kV；Bv59]的 2.89。主观一致性很好（kappa=0.86；P<0.001），与 OQ 相关性良好（rs=0.94，P<0.001）。
结论 与 SECT 相比，结合最新的核和单能量后处理的 DE CT 采集可改善支架可视化。使用 Qr59 内核从 DECT 90/Sn 150kV 采集获得的 50keV 单能量重建可获得最佳的整体结果。
