Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, Korea.
Radiology. 2013 Apr;267(1):155-63. doi: 10.1148/radiol.12112735. Epub 2013 Jan 17.
To determine the diagnostic performance of dual-energy computed tomography (CT) by using virtual unenhanced CT to characterize adrenal masses.
This study is retrospective, HIPAA-compliant, and approved by the institutional review board. Between December 2009 and June 2010, 49 patients with 49 adrenal masses underwent 120-kVp unenhanced CT and 80-kVp and 140-kVp early and delayed contrast agent-enhanced dual-energy CT. Early virtual unenhanced (EVU) and delayed virtual unenhanced (DVU) CT images were composed of data sets of early and delayed contrast-enhanced CT, respectively. Adenomas were divided into lipid-rich adenoma and lipid-poor adenoma on the basis of lesion attenuation values measured according to unenhanced CT and percentage loss of enhancement. Absolute percentage loss of enhancement was calculated with the following equation: (CT(EE) - CT(DE)) × 100/(CT(EE) - CT(UE)), where CT(UE), CT(EE), and CT(DE) are adrenal mass attenuation values at unenhanced CT, early contrast-enhanced CT, and delayed contrast-enhanced CT, respectively. The sensitivity of adrenal protocol adenoma with delayed contrast-enhanced CT was obtained with a reference standard of unenhanced CT, pathologic examination, or size stability on follow-up examination findings. Lesion attenuation values measured on unenhanced CT, EVU CT, and DVU CT images were compared by using repeated measures analysis of variance with post hoc test.
Of 49 masses, 33 were adenomas and 16 were nonadenomas. Adenoma group was 18 lipid-rich adenomas and 15 lipid-poor adenomas. Mean attenuation values of the lipid-rich adenomas on EVU CT images (11.7 HU ± 9.5) were significantly greater than those on unenhanced CT images (0.7 HU ± 7.2) (P = .001) and DVU CT images (6.6 HU ± 8.4) (P = .01). The sensitivities of EVU CT and DVU CT for lipid-rich adenoma were 39% (seven of 18) and 61% (11 of 18), respectively. The sensitivity for adenoma with percentage loss of enhancement values calculated from virtual unenhanced CT and early and delayed contrast-enhanced CT was 100% (33 of 33).
Although adrenal protocol with dual-energy CT by using virtual unenhanced CT and washout rate can help diagnose all lipid-poor adenomas, it may miss lipid-rich adenomas that can be diagnosed on unenhanced CT images.
利用虚拟非增强 CT 来确定双能 CT 对肾上腺肿块的诊断性能。
本研究为回顾性研究，符合 HIPAA 规定，并经机构审查委员会批准。2009 年 12 月至 2010 年 6 月，49 例 49 个肾上腺肿块患者接受了 120 kVp 未增强 CT 和 80 kVp、140 kVp 早期和延迟对比剂增强双能 CT 检查。早期虚拟非增强（EVU）和延迟虚拟非增强（DVU）CT 图像分别由早期和延迟对比增强 CT 的数据集组成。根据未增强 CT 和增强百分比丢失测量的病变衰减值，将腺瘤分为富含脂质的腺瘤和脂质缺乏的腺瘤。绝对增强百分比丢失的计算公式为：（CT（EE）-CT（DE））×100/（CT（EE）-CT（UE）），其中 CT（UE）、CT（EE）和 CT（DE）分别是肾上腺肿块在未增强 CT、早期增强 CT 和延迟增强 CT 上的衰减值。用无增强 CT、病理检查或随访检查结果的大小稳定性作为参考标准，获得了延迟增强 CT 肾上腺方案腺瘤的敏感性。采用重复测量方差分析和事后检验比较了无增强 CT、EVU CT 和 DVU CT 图像上测量的病变衰减值。
49 个肿块中，33 个为腺瘤，16 个为非腺瘤。腺瘤组包括 18 个富含脂质的腺瘤和 15 个脂质缺乏的腺瘤。富含脂质的腺瘤在 EVU CT 图像上的平均衰减值（11.7 HU ± 9.5）明显大于在未增强 CT 图像上的平均衰减值（0.7 HU ± 7.2）（P =.001）和在 DVU CT 图像上的平均衰减值（6.6 HU ± 8.4）（P =.01）。EVU CT 和 DVU CT 对富含脂质的腺瘤的敏感性分别为 39%（18 例中的 7 例）和 61%（18 例中的 11 例）。通过虚拟非增强 CT 和早期及延迟对比增强 CT 计算的增强百分比丢失值对腺瘤的敏感性为 100%（33 例中的 33 例）。
尽管双能 CT 肾上腺方案使用虚拟非增强 CT 和洗脱率有助于诊断所有的脂质缺乏性腺瘤，但可能会漏诊可在非增强 CT 图像上诊断的富含脂质的腺瘤。
