OBJECTIVES To perform a systematic review on apparent diffusion coefficient (ADC) values of renal tumor subtypes and meta-analysis on the diagnostic performance of ADC for differentiation of localized clear cell renal cell carcinoma (ccRCC) from other renal tumor types. METHODS Medline, Embase, and the Cochrane Library databases were searched for studies published until May 1, 2019, that reported ADC values of renal tumors. Methodological quality was evaluated. For the meta-analysis on diagnostic test accuracy of ADC for differentiation of ccRCC from other renal lesions, we applied a bivariate random-effects model and compared two subgroups of ADC measurement with vs. without cystic and necrotic areas. RESULTS We included 48 studies (2588 lesions) in the systematic review and 13 studies (1126 lesions) in the meta-analysis. There was no significant difference in ADC of renal parenchyma using b values of 0-800 vs. 0-1000 (p = 0.08). ADC measured on selected portions (sADC) excluding cystic and necrotic areas differed significantly from whole-lesion ADC (wADC) (p = 0.002). Compared to ccRCC, minimal-fat angiomyolipoma, papillary RCC, and chromophobe RCC showed significantly lower sADC while oncocytoma exhibited higher sADC. Summary estimates of sensitivity and specificity to differentiate ccRCC from other tumors were 80% (95% CI, 0.76-0.88) and 78% (95% CI, 0.64-0.89), respectively, for sADC and 77% (95% CI, 0.59-0.90) and 77% (95% CI, 0.69-0.86) for wADC. sADC offered a higher area under the receiver operating characteristic curve than wADC (0.852 vs. 0.785, p = 0.02). CONCLUSIONS ADC values of kidney tumors that exclude cystic or necrotic areas more accurately differentiate ccRCC from other renal tumor types than whole-lesion ADC values. KEY POINTS • Selective ADC of renal tumors, excluding cystic and necrotic areas, provides better discriminatory ability than whole-lesion ADC to differentiate clear cell RCC from other renal lesions, with area under the receiver operating characteristic curve (AUC) of 0.852 vs. 0.785, respectively (p = 0.02). • Selective ADC of renal masses provides moderate sensitivity and specificity of 80% and 78%, respectively, for differentiation of clear cell renal cell carcinoma (RCC) from papillary RCC, chromophobe RCC, oncocytoma, and minimal-fat angiomyolipoma. • Selective ADC excluding cystic and necrotic areas are preferable to whole-lesion ADC as an additional tool to multiphasic MRI to differentiate clear cell RCC from other renal lesions whether the highest b value is 800 or 1000.

中文翻译：

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ADC值诊断透明细胞肾细胞癌的诊断测试准确性：系统评价和荟萃分析。

目的对肾肿瘤亚型的表观扩散系数（ADC）值进行系统评价，并就ADC鉴别局部透明细胞肾细胞癌（ccRCC）与其他肾肿瘤类型的诊断性能进行荟萃分析。方法检索Medline，Embase和Cochrane库数据库，以查找发表至2019年5月1日的研究，该研究报告了肾肿瘤的ADC值。方法学质量进行了评估。为了对ADC诊断ccRCC与其他肾脏病变的区别进行诊断测试准确性的荟萃分析，我们应用了双变量随机效应模型，并比较了有无囊性和坏死性区域的ADC测量的两个亚组。结果我们在系统评价中纳入了48项研究（2588处病变），在荟萃分析中纳入了13项研究（1126处病变）。使用b值0-800与0-1000（p = 0.08），肾实质的ADC无显着差异。在除囊性和坏死区域之外的选定部分（sADC）上测量的ADC与全病变ADC（wADC）有显着差异（p = 0.002）。与ccRCC相比，最小脂肪血管平滑肌脂肪瘤，乳头状RCC和发色团RCC的sADC显着降低，而瘤细胞瘤的sADC则更高。对于sADC和ccADCC区分其他肿瘤的敏感性和特异性的简要估计分别为80％（95％CI，0.76-0.88）和78％（95％CI，0.64-0.89），而sADC为77％（95％CI，0.59） wADC为-0.90）和77％（95％CI，0.69-0.86）。与wADC相比，sADC在接收机工作特性曲线下的面积更大（0.852对0.785，p = 0.02）。结论排除囊性或坏死区域的肾脏肿瘤的ADC值比全病变ADC值更准确地将ccRCC与其他肾脏肿瘤类型区分开。要点•肾肿瘤的选择性ADC，除囊性和坏死区域外，与全病变ADC相比，具有更好的区分能力，可以将透明细胞RCC与其他肾脏病变区分开，接受者工作特征曲线（AUC）下的面积为0.852对0.785。 ，分别为（p = 0.02）。•肾肿块的选择性ADC可以将透明细胞肾细胞癌（RCC）与乳头状RCC，发色团RCC，肿瘤细胞瘤和最小脂肪血管平滑肌脂肪瘤的区分分别提供80％和78％的中等敏感性和特异性。