体素内不相干运动扩散加权成像定量参数在肝脏良恶性病变诊断中的价值

Study on Diagnosis Value of Intravoxel Incoherent motion DWI in Hepatic Lesions

目的探讨体素内不相干运动扩散加权成像（IVIM DWI）定量参数在肝脏良恶性病变诊断中的价值。方法搜集肝占位性病变患者52例（共77个病灶）,包括原发性肝癌22例（28个病灶）、转移瘤15例（30个病灶）和肝血管瘤15例（19个病灶）,所有病例均经活检或追踪确诊。所有病例均行常规MRI平扫、IVIM DWI（11个b值）及多期动态增强扫描。测量参数包括：病灶及背景肝实质的表观扩散系数（ADC）、真实扩散系数（D）、灌注相关扩散系数（D~＊）、灌注分数（f）及血流相关参数（f×D~＊）。并计算病灶与背景肝实质相应参数的比值[ADC/ADC_0、D/D_0、f/f_0、D~＊/D~＊_0、（f×D~＊）/（f×D~＊）0]。方差分析各组肝脏病变间参数差异性,并受试者工作特征曲线（ROC）分析其诊断效能。结果肝血管瘤的ADC、D、ADC/ADC_0、及D/D_0均显著高于肝癌,其中D值的曲线下面积（AUC）最大（0.999）,相应的截断值为1.35×10^（-3）mm^2/s,对应敏感度与特异度分别为100%,96.4%;当D和ADC/ADC_0联合时,能完全区分两种病变,对应敏感度与特异度均为100%。D和ADC/ADC_0均能完全区分肝血管瘤和肝转移瘤,对应阈值分别为1.21×10^（-3）mm^2/s和1.28。肝癌ADC、D、ADC/ADC_0、及D/D_0均显著高于肝转移瘤,其中D/D_0的AUC值最大（0.879）;其在截断值为1.20时,其敏感度与特异度为67.9%,96.7%;当D/D_0和D联合时,诊断效能达0.893,相应敏感度与特异度为96.7%,75.0%。f、D~＊和f×D~＊值在各组间未见显著性差异。结论 IVIM DWI相关参数（ADC、D、ADC/ADC_0、及D/D_0）能定量评估肝脏良恶性病变特征,其中病灶与背景肝实质扩散比值（ADC/ADC_0和D/D_0）能提高肝脏良恶性病变诊断效能。

Objective To evaluate the value of IVIM DWI in the differential diagnosis of benign and malignant liver tumors. Methods 52 cases（ 77 lesions） with liver lesions confirmed by pathology or follow-up were collected,including primary liver cancer 22 cases（ 28 lesions）,metastatic tumor 15 cases（ 30 lesions） and hepatic hemangioma 15 cases（ 19 lesions）. All cases were performed routine non-enhanced MRI scans and IVIM DWI（ 11 b values） and multi-phase dynamic contrast enhancement MRIs. The measured parameters include： the apparent diffusion coefficients,true diffusion coefficients,perfusion-related diffusion coefficients,perfusion fraction and blood-flow-related parameters（ f and D~＊product）in the lesions and corresponding background liver parenchyma,recorded respectively as（ ADC,D,D~＊,f and f × D~＊） and[ADC_0,D_0,D~＊_0,f_0 and（ f × D~＊）0]. Then calculate the ratio of the corresponding parameters of the lesion to the parenchyma of the background,recorded as ADC/ADC_0,D/D_0,D~＊/D~＊_0,f/f_0,（ f × D~＊）/（ f × D~＊）0. Variance analysis was performed to examine the parameter differences between liver lesions and to generate the operating characteristic curve of the subjects before the diagnostic performance was evaluated. Results First,the ADC,D,ADC/ADC_0,and D/D_0 of the hepatic hemangioma are significantly higher than those of HCC,where the D value corresponds to the largest area under curve（ 0. 999）. When the D value was 1. 39 × 10^（-3） mm^2/s,the specificity and sensitivity to differentiate hemangioma from hepatocellular carcinoma were 100% and 96%. When combined with D and ADC/ADC_0,the two types of lesions can be completely differentiated,and the corresponding sensitivity and specificity are 100%. Second,Both D and ADC/ADC_0 can differentiate hepatic hemangioma and hepatic metastases completely,and the corresponding thresholds were 1. 21 × 10^（-3） mm^2/s and 1. 28. Third,the ADC,D,ADC/ADC_0,and D/D_0 of HCC are significantly higher than those of hepatic metastases,and the D/D_0 AUC is the largest（ 0. 879）. When the threshold of D/D_0 is 1. 20,its sensitivity and specificity are67. 9%,96. 7%; When combined D/D_0 and D,the AUC reaches up to 0. 893,thecorresponding sensitivity and specificity are 96. 7%,75%. Forth,There were no significant difference in f,D~＊and f × D~＊values between the groups. Conclusion The parameters of IVIM DWI（ ADC,D,ADC/ADC_0,and D/D_0） can quantitatively characterize benign and malignant liver tumors,and the ratio of IVIM diffusion quantitative parameters of the lesion to the parenchyma of the background（ ADC/ADC_0 and D/D_0） can contribute to the diagnostic value of liver lesions.