Department of Radiology, New York University Langone Medical Center, New York, 10016, USA.
AJR Am J Roentgenol. 2010 Nov;195(5):W344-51. doi: 10.2214/AJR.10.4688.
The purpose of our study was to assess the utility of the apparent diffusion coefficient (ADC) in distinguishing low-grade and high-grade clear cell renal cell carcinoma (ccRCC).
The cases of 57 patients with pathologically proven ccRCC who underwent preoperative MRI, including diffusion-weighted imaging, were retrospectively assessed. ADC values were obtained from ADC maps calculated using b-value combinations of 0 and 400 s/mm² and of 0 and 800 s/mm² (hereafter referred to as ADC-400 and ADC-800). Lesions were also evaluated for an array of conventional MRI features. A single expert uropathologist reviewed all slides to determine nuclear grade. The utility of ADC for detecting high-grade ccRCC, alone and in combination with conventional MRI features, was assessed using receiver operating characteristic (ROC) analysis and binary logistic regression.
ADC-400 and ADC-800 were significantly lower among high-grade than among low-grade ccRCC (2.24 ± 0.50 mm²/s vs 1.59 ± 0.57 mm²/s for ADC-400, p < 0.001; 1.85 ± 0.40 mm²/s vs 1.28 ± 0.48 mm²/s for ADC-800; p < 0.001). The area under the ROC curve for identifying high-grade ccRCC using ADC-400 and ADC-800 was 0.801 and 0.824 respectively (p = 0.606), with optimal thresholds, sensitivity, and specificity as follows: ADC-400: 2.17 mm²/s, 88.5%, 64.5% and ADC-800: 1.20 mm²/s, 65.4%, 96.0%. Using multivariate logistic regression, only necrosis (p = 0.0229) and perinephric fat invasion (p = 0.0160) were retained among conventional imaging features as independent risk factors for high-grade ccRCC. The accuracy of the logistic regression model for predicting high-grade ccRCC was significantly improved by inclusion of either ADC-400 (p = 0.0143) or ADC-800 (p = 0.015).
ADC is significantly lower in high-grade ccRCC compared with low-grade ccRCC and increases the accuracy for detecting high-grade ccRCC compared with conventional MRI features alone.
本研究旨在评估表观扩散系数（ADC）在鉴别低级别和高级别透明细胞肾细胞癌（ccRCC）中的效用。
回顾性分析了 57 例经病理证实的 ccRCC 患者的病例资料，这些患者均在术前接受了包括扩散加权成像在内的 MRI 检查。通过计算 b 值组合为 0 和 400 s/mm² 和 0 和 800 s/mm² 的 ADC 图（分别称为 ADC-400 和 ADC-800），获得 ADC 值。病变还评估了一系列常规 MRI 特征。一位经验丰富的泌尿病理学家审查了所有切片以确定核分级。使用受试者工作特征（ROC）分析和二元逻辑回归评估 ADC 单独和与常规 MRI 特征联合用于检测高级别 ccRCC 的效用。
高级别 ccRCC 的 ADC-400 和 ADC-800 值明显低于低级别 ccRCC（ADC-400 分别为 2.24 ± 0.50 mm²/s 和 1.59 ± 0.57 mm²/s，p < 0.001；ADC-800 分别为 1.85 ± 0.40 mm²/s 和 1.28 ± 0.48 mm²/s，p < 0.001）。使用 ADC-400 和 ADC-800 识别高级别 ccRCC 的 ROC 曲线下面积分别为 0.801 和 0.824（p = 0.606），最佳阈值、敏感性和特异性如下：ADC-400：2.17 mm²/s、88.5%、64.5%和 ADC-800：1.20 mm²/s、65.4%、96.0%。使用多变量逻辑回归，只有坏死（p = 0.0229）和肾周脂肪侵犯（p = 0.0160）在常规影像学特征中被保留为高级别 ccRCC 的独立危险因素。纳入 ADC-400（p = 0.0143）或 ADC-800（p = 0.015）后，逻辑回归模型预测高级别 ccRCC 的准确性显著提高。
高级别 ccRCC 的 ADC 值明显低于低级别 ccRCC，并且与单独使用常规 MRI 特征相比，ADC 值提高了检测高级别 ccRCC 的准确性。
