初步评估双源CT双能量技术在孤立性肺结节研究中的价值

目的：探讨双源CT双能量技术在孤立性肺结节（SPN）研究中的临床应用价值。方法：40例SPN患者经病理证实并行胸部CT常规平扫及双能量模式增强扫描,双能量增强扫描数据传入Siemens双源CT专用＂Dual-Energy＂工作站,选择＂Liver VNC＂模式进行自动能量减影,得到虚拟平扫图像及碘分布图像。对SPN的虚拟平扫图像CT值和常规平扫图像SPN的CT值进行比较研究;对SPN内的碘分布图像CT值与SPN的强化值（增强图像SPN的CT值-平扫图像SPN的CT值）进行比较研究;对利用碘分布图像CT值和强化值在诊断SPN的符合率进行比较研究;研究虚拟平扫图像显示SPN内钙化灶以及纵隔淋巴结钙化灶的能力;将双能量扫描模式辐射剂量与单源扫描模式辐射剂量进行比较。结果：SPN的虚拟平扫图像CT值和常规平扫图像的CT值以及碘分布图像CT值与强化值显示出良好的一致性（相关系数分别为0.89,0.91）。以20HU作为阈值,利用SPN强化值评估其良恶性的准确度、敏感度、特异度分别为67.5%、71.4%、58.3%;利用SPN碘分布图像CT值评估其良恶性的准确度、敏感度、特异度分别为75.0%、74.2%、66.7%。虚拟平扫图像对SPN内钙化灶及纵隔淋巴结钙化的显示率为94.2%。双能量扫描模式平均辐射剂量（230.74±36.12）mGy.cm与单源扫描模式平均辐射剂量（238.14±29.12）mGy.cm,差异无统计学意义（t=0.12,P〉0.05）。结论：双能量扫描技术能够一次扫描获得虚拟平扫图及碘剂分布图,不存在数据采集的位置和时间差,能够成功检出强化后SPN内的钙化灶,选择性重建SPN的虚拟平扫图像代替胸部常规平扫则可以明显减低患者的辐射剂量。

Preliminary evaluation of dual-energy CT technique in the study of solitary pulmonary nodules

Objective：To evaluate the clinical utility of dual-energy CT technique in the study of solitary pulmonary nodules.Methods：40 patients with SPN proved pathologically were examined by conventional chest CT and the DE mode of Somatom Definition scanner.By using a modified prototype of the Liver VNC application of dual energy（Siemens Medical Solutions） on a dedicated research MultiModality Workplace workstation,virtual nonenhanced and iodine-enhanced images were calculated from the enhanced scan data.CT vaule of SPNs on virtual nonenhanced and nonenhanced weighted average images,as well as CT vaule of the SPNs on iodine-enhanced image and the degree of enhancement（CT number on enhanced weighted average image minus CT number on nonenhanced weighted average image） were compared.The CT vaule of the SPN on iodine-enhanced image and the degree of enhancement were compared in terms of their diagnostic accuracy for distinguishing malignant and benign nodules.Detectability of calcifications within the SPN and lymph nodes on virtual nonenhanced image were compared with those on the nonenhanced weighted average image.Radiation dose of dual-energy CT was compared with that of single-energy CT.Results：CT vaule of SPN on nonenhanced weighted average and virtual nonenhanced images showed good agreement（r=0.89,t=6.84,P0.001）.The CT vaule of SPN on iodine-enhanced image and the degree of enhancement also showed good agreement（r=0.91,t=6.98,P0.001）.Diagnostic accuracy with a cut off of 20HU for malignancy by using CT vaule on iodine-enhanced image was comparable to that by using the degree of enhancement（sensitivity,74.2% and 71.4%;specificity,66.7% and 58.3%;accuracy,75.0% and 67.5%,respectively）.On virtual nonenhanced image,94.2%（33 of 35） of calcifications in the SPNs and lymph nodes were detected.The average dose-length product of a single scanning covering the full thorax using DE CT was（230.74±36.12）mGy·cm,was not significantly different from that of single-energy CT（238.14±29.12）mGy·cm.Conclusion：Dual-energy technique simultaneously provides virtual nonenhanced image and an iodine-enhanced image from a single scanning.DE CT allows differentiation of calcification from enhancing tissue by subtraction of the iodine component.Optional reconstruction of a virtual nonenhanced image after DE CT scanning may save the amount of radiation of an additional nonenhanced CT scanning.