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目的评价双能量CT虚拟平扫技术对肾上腺肿块的定性诊断价值。材料与方法这项回顾性研究符合HIPAA标准并通过机构审查委员会批准。在2009年12月—2010年6月间,共49例单侧肾上腺肿物病人行120kV平扫及80kV和140kV双能量早期和延迟期增强扫描。根据早期和延迟期的增强CT原始数据分别重组出早期虚拟平扫(EVU)和延迟期虚拟平扫(DVU)影像。基于平扫的CT值和增强后CT值变化的百分比将腺瘤分为富脂肪和乏脂肪腺瘤。增强后CT值变化的绝对百分比计算公式如下:(CTEE-CTDE)×100/(CTEE-CTUE),其中,CTUE、CTEE和CTDE分别代表肾上腺肿块平扫、增强早期和延迟期的CT值。以CT平扫、病理检查或随访过程中肿块大小不变作为参考标准判断肾上腺腺瘤扫描方案中增强延迟期CT的诊断敏感性。病变在平扫、EVUCT和DVUCT影像上所测得的CT值采用重复测量事后检验方差分析进行比较。结果 49个肿块中,33个为腺瘤,16个为非腺瘤。腺瘤组中18个为富脂肪腺瘤,15个为乏脂肪腺瘤。富脂肪腺瘤EVUCT影像的平均CT值[(11.7±9.5)HU]显著高于平扫CT影像[(0.7±7.2)HU](P=0.001)和DVUCT影像[(6.6±8.4)HU](P=0.01)。EVUCT和DVUCT诊断富脂肪腺瘤的敏感度分别为39%(7/18)和61%(11/18)。通过虚拟平扫、增强早期和延迟期计算出CT值变化的百分比诊断腺瘤的敏感度为100%(33/33)。结论肾上腺双能量CT扫描方案的虚拟平扫技术和增强后CT值变化率有助于诊断所有的乏脂肪腺瘤,但是它有可能漏诊那些CT平扫就可以诊断的富脂肪腺瘤。
Objective To evaluate the value of dual-energy virtual CT scan in the qualitative diagnosis of adrenal masses. Materials and Methods This retrospective study was HIPAA compliant and approved by the Institutional Review Board. Between December 2009 and June 2010, a total of 49 patients with unilateral adrenal masses underwent 120 kV plain scan and 80 kV and 140 kV dual-energy early and delayed enhanced phases. Early virtual scan (EVU) and delayed virtual scan (DVU) images were reconstructed based on the early and delayed enhanced CT raw data respectively. Adenomas were divided into fatty and dystrophic adenomas based on the percentage of CT scan values and post-contrast CT changes. The absolute percent change of CT value after the enhancement is calculated as follows: (CTEE-CTDE) × 100 / (CTEE-CTUE), where CTUE, CTEE and CTDE represent the adrenal masses respectively. CT values of early and late phases are enhanced. To CT scan, pathological examination or follow-up size of the same mass as a reference standard to determine the diagnosis of adrenal adenomas scan delay enhanced CT diagnostic sensitivity. The lesion was measured on plain and EVUCT and DVUCT images by comparing repeated measures ANOVA. Results Of the 49 tumors, 33 were adenomas and 16 were non-adenomas. Adenoma group of 18 for the fat-rich adenomas, 15 for the lack of fat adenoma. The average CT value of (11.7 ± 9.5) HU in patients with adenocarcinoma of the fatty liver was significantly higher than that of the plain CT images [(0.7 ± 7.2) HU] (P = 0.001) and DVUCT images [(6.6 ± 8.4) 0.01). The sensitivity of EVUCT and DVUCT in diagnosing fatty adenoma was 39% (7/18) and 61% (11/18), respectively. The percentage of changes in CT values calculated by virtual scan, enhanced early and delayed phases was 100% (33/33) for the diagnosis of adenomas. Conclusions The virtual scan of the adrenal dual-energy CT scan and the rate of change of post-contrast CT values are helpful for the diagnosis of all patients with steato-lipadenomas, but it is possible to miss the diagnosis of fatty adenomas with CT scan.