双能CT双期增强扫描结合虚拟平扫对肾脏透明细胞癌的诊断价值

Diagnostic value of dual-phase contrast enhancement CT combined with virtual non-enhanced images by dual-energy CT in clear cell renal cell carcinoma

目的探讨双能CT双期增强结合虚拟平扫对肾脏透明细胞癌的诊断价值。方法对60例临床怀疑肾脏透明细胞癌的患者进行前瞻性研究，进行双能CT的单能平扫及双能皮髓交界早期、实质期增强扫描，采用虚拟平扫后处理软件生成虚拟平扫图像，分别根据虚拟平扫结合双期增强及单纯双期增强图像进行诊断，以病理结果为标准，计算两者诊断。肾脏透明细胞癌的准确率，并以X^2检验比较；以Wilcoxon秩和检验比较常规平扫和虚拟平扫图像对肿瘤的显示；以配对样本t检验比较患者所接受的单期X线辐射剂量和总辐射剂量差异、常规平扫与虚拟平扫图像肿瘤的CT值差异。结果虚拟平扫结合双能CT双期增强图像对透明细胞癌的诊断准确率高于单纯双期增强[分别为93．3％（56／60）和78．3％（47／60）；X^2=5．6，P〈0．05]。常规平扫显示42例肾透明细胞癌病灶，对肿瘤显示优、良、一般和差的分别为22、12、4和4例，虚拟平扫分别为26、10、3和3例，差异无统计学意义（Z：0．00，P=1．00）。虚拟平扫的单期CTDIvol（8．85±1．28）mGy、DLP剂量（196．45±21．12）mGy·cm和总的CTDIvol（17．69±2．35）mGy、DLP剂量（392．90±42．25）mGy·cm均低于常规平扫[分别为（10．20±1．44）mGy、（218．29±29．60）mGy·cm、（30．61±3．27）mGy和（654．86±88．81）mGy·cm]，t值分别为4．21、3．58、23．63、16．12，P值均〈0．05。常规平扫和虚拟平扫的cT值分别为（34．94±7．00）和（39．37±6．35）HU，差异有统计学意义（t=-14．39，P〈0．05）。结论双能CT皮髓交界早期及实质期双期增强结合虚拟平扫对肾脏透明细胞癌的诊断价值较大，对多数患者可以做出准确诊断，并明显降低辐射剂量。

Objective To explore the diagnositic value of dual-phase contrast enhancement CT combined with virtual non-enhanced images by dual-energy CT in clear cell renal cell carcinoma. Methods Sixty patients who were suspected of clear cell renal cell carcinoma underwent non-enhanced CT and contrast enhancement CT of early interface-phase between cortex -medulla and parenehymal phase on a dual-energy CT. The true non-enhanced kidney CT（TNCT）was performed in a single-energy acquisition mode, but the dual-phase contrast enhancement CT were performed in a dual-energy mode of 80 kV and 140 kV respectively. The virtual non-enhanced CT （VNCT） images were derived from the data of early interfacephase using liver virtual non-contrast software. The diagnosises according to VNCT combined dual-phase contrast enhancement CT and dual-phase contrast enhancement CT only were made respectively and compared with X2 test. Between the true non-contrast CT and the virtual non-contrast CT, the image quality was compared with Wilcoxon test;The radiation dose of volume CT dose index （CTDIvol） and dose length product（DLP） in a single-phase and total examination, the mean CT HU values of the turnouts were compared with t test. Results The accuracy of VNCT combined dual-phase contrast enhancement CT was higher than that of dual-phase contrast enhancement CT only [ 93.3% （56/60） vs. 78.3% （47/60） ;X^2 = 5.6 ,P 〈 0. 05 ]. The detective ability （score） of VNCT was near to that of TNCT and the difference was not obvious （Z = 0. 00, P 〉 0. 05 ）. The radiation dose of volume CT dose index （ CTDIvol ） and dose length product（DLP） in a single phase and total examination of VNCT [ （8.85 ± 1.28 ） mGy, （196. 45 ± 21.12） mGy-cm,（17.69±2.35） mGy, （ 392. 90 ± 42. 25 ） mGy.cm] were lower than that of TNCT ] （ 10. 20 ± 1.44 ） mGy, （ 218.29 ± 29. 60） mGy . cm, （ 30. 61 ± 3.27 ） mGy and （ 654. 86 ± 88. 81 ） mGy . cm I ,t =4. 21,3.58,23.63,16. 12 respectively, P 〈0. 05. The mean CT HU values of tumours on VNCT images was higher than that on TNCT images and the difference was significant [ （39. 37 ± 6. 35 ） vs. （ 34. 94 ± 7.00 ） HU, t = - 14. 39, P 〈 0.05 ]. Conclusions The diagnositic value of dual-phase contrast enhancement CT combined virtual non-enhanced CT by dual-energy CT for clear cell renal cell carcinoma was obvious, most tumours can be diagnosed correctly, and the radiate dose can be decreased obviously, the normal single-energy non-enhanced and contrast enhancement CT might be replaced in the future.