From the Departments of Radiology (C.S., B.P., S.H., P.D., R.C.N., D.M.) and Biostatistics and Bioinformatics (A.E.F.), Duke University Medical Center, Box 3808 Erwin Rd, Durham, NC 27710; Department of Diagnostic and Interventional Radiology, University Hospital of Tuebingen, Tuebingen, Germany (C.S., K.N.); and Department of Computed Tomography, Siemens Medical Solutions USA, Malvern, Pa (J.C.R.).
Radiology. 2018 Jun;287(3):874-883. doi: 10.1148/radiol.2018171657. Epub 2018 Feb 22.
Purpose To investigate the relationship between energy level of virtual monoenergetic (VM) imaging and sensitivity in the detection of minimally enhancing renal lesions. Materials and Methods Phantoms simulating unenhanced and contrast material-enhanced renal parenchyma were equipped with inserts containing different concentrations of iodine (range, 0-1.15 mg iodine per milliliter). A total of 180 patients (117 men; mean age, 65.2 years ± 13.0 [standard deviation]) with 194 (62 solid, 132 cystic) renal lesions larger than 10 mm in diameter underwent unenhanced single-energy CT and contrast-enhanced dual-energy CT. VM imaging data sets were created for 70, 80, 90, and 100 keV. Renal lesions were measured, and enhancement was calculated. Area under the receiver operating characteristic curve (AUC) for renal lesion characterization was determined by using the DeLong method. Results The AUC was highest at 70 keV and decreased as energy increased toward 100 keV. AUC in the phantom decreased from 98% (95% confidence interval [CI]: 95, 100) at 70 keV to 88% (95% CI: 79, 96) at 100 keV (P = .004). AUC in patients decreased from 96% (95% CI: 94, 98) at 70 keV to 79% (95% CI: 71, 86) at 100 keV (P = .001). In patients with an enhancement threshold of 15 HU, sensitivity in the detection of solid renal lesions decreased between from 91% (49 of 62 [95% CI: 78, 97]) at 70 keV to 48% (33 of 62 [95% CI: 25, 71]) at 100 keV (P < .05), with no change in specificity (93% [120 of 132 {95% CI: 87, 97}] at 70 keV, 97% [125 of 132 {95% CI: 92, 99}] at 100 keV). Conclusion There is a reduction in diagnostic accuracy for renal lesion characterization with increasing VM imaging energy. The 70-keV setting may provide an optimal trade-off between sensitivity and specificity. RSNA, 2018 Online supplemental material is available for this article.
目的 旨在研究虚拟单能量（VM）成像的能量水平与检测最小增强性肾病变的敏感性之间的关系。
材料与方法 模拟未增强和对比增强肾实质的体模配备有含有不同碘浓度（范围，0-1.15 毫克碘/毫升）的插入物。共有 194 个（62 个实性，132 个囊性）直径大于 10 毫米的肾病变患者（117 名男性；平均年龄 65.2 岁±13.0 [标准差]）接受了未增强单能 CT 和对比增强双能 CT 检查。为 70、80、90 和 100 keV 分别创建了 VM 成像数据集。对肾病变进行了测量，并计算了增强程度。采用 DeLong 法确定用于肾病变特征描述的受试者工作特征曲线（AUC）下面积。
结果 在 70 keV 时 AUC 最高，随着能量向 100 keV 增加而降低。体模中的 AUC 从 70 keV 时的 98%（95%置信区间[CI]：95，100）下降至 100 keV 时的 88%（95% CI：79，96）（P =.004）。患者中的 AUC 从 70 keV 时的 96%（95% CI：94，98）下降至 100 keV 时的 79%（95% CI：71，86）（P =.001）。在增强阈值为 15 HU 的患者中，实性肾病变的检测敏感性从 70 keV 时的 91%（62 例中的 49 例[95% CI：78，97]）下降至 100 keV 时的 48%（62 例中的 33 例[95% CI：25，71]）（P <.05），特异性无变化（70 keV 时为 93%（132 例中的 120 例[95% CI：87，97]），100 keV 时为 97%（132 例中的 125 例[95% CI：92，99]））。
结论 随着 VM 成像能量的增加，肾病变特征描述的诊断准确性降低。70 keV 设定可能在敏感性和特异性之间提供了最佳的权衡。
RSNA，2018 在线补充材料可为本文提供。
