From the Department of Radiology, Mayo Clinic, Rochester, MN.
Invest Radiol. 2020 Apr;55(4):226-232. doi: 10.1097/RLI.0000000000000634.
The aims of this study were to investigate the feasibility of using a universal abdominal acquisition protocol on a photon-counting detector computed tomography (PCD-CT) system and to compare its performance to that of single-energy (SE) and dual-energy (DE) CT using energy-integrating detectors (EIDs).
Iodine inserts of various concentrations and sizes were embedded into different sizes of adult abdominal phantoms. Phantoms were scanned on a research PCD-CT and a clinical EID-CT with SE and DE modes. Virtual monoenergetic images (VMIs) were generated from PCD-CT and DE mode of EID-CT. For each image type and phantom size, contrast-to-noise ratio (CNR) was measured for each iodine insert and the area under the receiver operating characteristic curve (AUC) for iodine detectability was calculated using a channelized Hotelling observer. The optimal energy (in kiloelectrovolt) of VMIs was determined separately as the one with highest CNR and the one with the highest AUC. The PCD-CT VMIs at the optimal energy were then compared with DE VMIs and SE images in terms of CNR and AUC.
Virtual monoenergetic image at 50 keV had both the highest CNR and highest AUC for PCD-CT and DECT. For 1.0 mg I/mL iodine and 35 cm phantom, the CNRs of 50 keV VMIs from PCD-CT (2.01 ± 0.67) and DE (1.96 ± 0.52) were significantly higher (P < 0.001, Wilcoxon signed-rank test) than SE images (1.11 ± 0.35). The AUC of PCD-CT (0.98 ± 0.01) was comparable to SE (0.98 ± 0.01), and both were slightly lower than DE (0.99 ± 0.01, P < 0.01, Wilcoxon signed-rank test). A similar trend was observed for other phantom sizes and iodine concentrations.
Virtual monoenergetic images at a fixed energy from a universal acquisition protocol on PCD-CT demonstrated higher iodine CNR and comparable iodine detectability than SECT images, and similar performance compared with DE VMIs.
本研究旨在探讨在光子计数探测器 CT（PCD-CT）系统上使用通用腹部采集方案的可行性，并将其性能与使用能量积分探测器（EID）的单能（SE）和双能（DE）CT 进行比较。
将不同浓度和大小的碘嵌入物嵌入到不同大小的成人腹部体模中。体模在研究用 PCD-CT 和临床 EID-CT 上进行 SE 和 DE 模式扫描。从 PCD-CT 和 EID-CT 的 DE 模式生成虚拟单能量图像（VMI）。对于每种图像类型和体模大小，测量每个碘嵌入物的对比噪声比（CNR），并使用通道化 Hotelling 观察者计算碘可检测性的受试者工作特征曲线（ROC）下面积（AUC）。单独确定 VMI 的最佳能量（千电子伏特），即具有最高 CNR 和最高 AUC 的能量。然后，根据 CNR 和 AUC，将 PCD-CT 的 VMI 与 DE VMI 和 SE 图像进行比较。
PCD-CT 和 DECT 的 50keV VMI 具有最高的 CNR 和最高的 AUC。对于 1.0mg I/mL 碘和 35cm 体模，PCD-CT（2.01±0.67）和 DE（1.96±0.52）的 50keV VMI 的 CNR 明显高于 SE 图像（1.11±0.35，P<0.001，Wilcoxon 符号秩检验）。PCD-CT（0.98±0.01）的 AUC 与 SE（0.98±0.01）相当，均略低于 DE（0.99±0.01，P<0.01，Wilcoxon 符号秩检验）。对于其他体模大小和碘浓度，也观察到类似的趋势。
PCD-CT 上通用采集方案固定能量的 VMI 显示出比 SECT 图像更高的碘 CNR 和可比的碘可检测性，并且与 DE VMI 的性能相似。
