Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905.
Institut für Informatik, Technische Universität München, Garching bei München, Germany.
Acad Radiol. 2018 Oct;25(10):1270-1276. doi: 10.1016/j.acra.2018.01.007. Epub 2018 Feb 14.
This study aims to investigate the performance of a whole-body, photon-counting detector (PCD) computed tomography (CT) system in differentiating urinary stone composition.
Eighty-seven human urinary stones with pure mineral composition were placed in four anthropomorphic water phantoms (35-50 cm lateral dimension) and scanned on a PCD-CT system at 100, 120, and 140 kV. For each phantom size, tube current was selected to match CTDI (volume CT dose index) to our clinical practice. Energy thresholds at [25, 65], [25, 70], and [25, 75] keV for 100, 120, and 140 kV, respectively, were used to generate dual-energy images. Each stone was automatically segmented using in-house software; CT number ratios were calculated and used to differentiate stone types in a receiver operating characteristic (ROC) analysis. A comparison with second- and third-generation dual-source, dual-energy CT scanners with conventional energy integrating detectors (EIDs) was performed under matching conditions.
For all investigated settings and smaller phantoms, perfect separation between uric acid and non-uric acid stones was achieved (area under the ROC curve [AUC] = 1). For smaller phantoms, performance in differentiation of calcium oxalate and apatite stones was also similar between the three scanners: for the 35-cm phantom size, AUC values of 0.76, 0.79, and 0.80 were recorded for the second- and third-generation EID-CT and for the PCD-CT, respectively. For larger phantoms, PCD-CT and the third-generation EID-CT outperformed the second-generation EID-CT for both differentiation tasks: for a 50-cm phantom size and a uric acid/non-uric acid differentiating task, AUC values of 0.63, 0.95, and 0.99 were recorded for the second- and third-generation EID-CT and for the PCD-CT, respectively.
PCD-CT provides comparable performance to state-of-the-art EID-CT in differentiating urinary stone composition.
本研究旨在探讨全身体光子计数探测器（PCD） CT 系统在鉴别尿路结石成分方面的性能。
将 87 个人类尿路结石置于 4 个仿体水模（35-50cm 侧径）中，并在 PCD-CT 系统上于 100、120 和 140kV 下进行扫描。对于每个体模尺寸，选择管电流以使容积 CT 剂量指数（CTDIvol）与我们的临床实践相匹配。分别使用 25、65、70 和 75keV 的能量阈值生成双能图像。使用内部软件自动对每个结石进行分割；计算 CT 值比，并在受试者工作特征（ROC）分析中用于鉴别结石类型。在匹配条件下，与第二代和第三代双源、双能 CT 扫描仪（使用常规能量积分探测器（EID））进行比较。
在所有研究的设置和较小的体模中，尿酸和非尿酸结石之间实现了完美分离（ROC 曲线下面积（AUC）=1）。对于较小的体模，三种扫描仪在鉴别草酸钙和磷灰石结石方面的性能也相似：对于 35cm 体模尺寸，第二代和第三代 EID-CT 以及 PCD-CT 的 AUC 值分别为 0.76、0.79 和 0.80。对于较大的体模，PCD-CT 和第三代 EID-CT 在这两项鉴别任务中均优于第二代 EID-CT：对于 50cm 体模尺寸和尿酸/非尿酸鉴别任务，第二代和第三代 EID-CT 以及 PCD-CT 的 AUC 值分别为 0.63、0.95 和 0.99。
PCD-CT 在鉴别尿路结石成分方面与最先进的 EID-CT 具有相当的性能。
