Objective To investigate the diagnostic value of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI)in preoperative Fuhrman grading of clear-cell renal-cell carcinoma (CCRCC).Methods The imaging and pathological materials of 42 cases with pathologically-confirmed CCRCC were retrospectively assessed.According to Fuhr-man grading,the patients were divided into the low-grade group (n =21)and high-grade group (n =21).Based on a bi-exponential model,these parameters,including the standard apparent diffusion coefficient (ADC),the true diffusion coef-ficient (D),perfusion-related diffusion coefficient (D*),and perfusion fraction (f),were compared between these two groups with nonparametric test (Mann-Whitney U).And the receiver operating characteristic (ROC)analysis was used to compare the predictive values in preoperatively Fuhrman grading CCRCC among four parameters.Results The average ADC,D,D* and f values of the low-grade group were (1.62 ±0.24)×10 -3 mm2 /s,(1.73 ±0.18)×10 -3 mm2 /s, (72.18 ±90.28)×10 -3 mm2 /s and 0.27 ±0.08,respectively.Meanwhile,these values of the high-grade group were (1.10 ±0.58)×10 -3 mm2 /s,(1.40 ±0.20)×10 -3 mm2 /s,(109.46 ±129.07)×10 -3 mm2 /s and 0.15 ±0.09,re-spectively.The differences in ADC,D value and f value were statistically significant between these two groups (all P <0.05);but no statistically significant difference was found in D* value between these two groups (P >0.05).The areas under the ROC curve of ADC,D value and f value were 0.768,0.931 and 0.83 respectively.According to maximum Youden index,the optimal threshold value for diagnosis was 1.14 ×10 -3 mm2 /s,1.59 ×10 -3 mm2 /s,and 0.18,respec-tively.Conclusion The IVIM-DWI can be helpful in preoperative Fuhrman grading of CCRCC,and D value has the best diagnostic efficacy.%目的：探讨磁共振体素内不相干运动扩散加权成像（IVIM-DWI）检查对肾透明细胞癌（CCRCC）的术前分级诊断效能。方法经手术病理检查证实的 CCRCC 患者42例，依据 Fuhrman 核分级法将其分为低级别组（21例）和高级别组（21例）。对两组患者的术前磁共振检查结果进行分析，比较两组表观扩散系数（ADC）、真实扩散系数（D）、灌注相关扩散系数（D*）和灌注分数（f），采用受试者工作特性（ROC）曲线分析上述各参数对 CCRCC的分级诊断效能。结果低级别组的 ADC、D、D*、f 值分别为（1．62±0．24）×10－3 mm2／s、（1．73±0．18）×10－3 mm2／s、（72．18±90．28）×10－3 mm2／s、0．27±0．08，高级别组分别为（1．10±0．58）×10－3 mm2／s、（1．40±0．20）×10－3 mm2／s、（109．46±129．07）×10－3 mm2／s、0．15±0．09；两组的 ADC、D、f 值相比，P 均＜0．05；两组的 D*值相比，P ＞0．05。ADC、D、f 值鉴别高低级别 CCRCC 的 ROC 曲线下面积分别为0．768、0．931、0．830，相应的最佳诊断阈值分别为1．14×10－3 mm2／s、1．59×10－3 mm2／s、0．18。结论术前磁共振 IVIM-DWI 检查有助于 CCRCC 的分级诊断，其中 D 值具有较高的诊断效能。
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