Jhaveri Kartik S, Elmi Azadeh, Hosseini-Nik Hooman, Hedgire Sandeep, Evans Andrew, Jewett Michael, Harisinghani Mukesh
1 Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, ON, M5G 2M9, Canada.
2 Division of Abdominal Imaging and Interventional Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
AJR Am J Roentgenol. 2015 Jul;205(1):W79-86. doi: 10.2214/AJR.14.13245.
The purpose of this study was to evaluate the diagnostic performance of chemical-shift MRI in the differentiation of clear cell renal cell carcinoma (RCC) from minimal-fat angiomyolipoma (AML) and non-clear cell RCC.
In this retrospective study, 97 patients with solid renal tumors without macroscopic fat and with a pathologic diagnosis of clear cell RCC (n = 40), non-clear cell RCC (n = 31), or minimal-fat AML (n = 26) who had undergone renal chemical-shift MRI were included. Size, location, morphology, and signal intensity (SI) of the tumors and the contralateral normal kidneys on T2-weighted and in-phase and opposed-phase images were recorded by readers blinded to the pathology. Percentage tumor-to-renal parenchymal SI drop (percentage SI drop) was calculated and correlated to tumor histology. The statistical analysis was done using Kruskal-Wallis, one-way ANOVA, chi-square, and Fisher exact tests.
The percentage SI drop was significantly higher in clear cell RCC compared with non-clear cell RCC and minimal-fat AML (p < 0.001). Percentage SI drop of greater than 20% had 57.5% sensitivity, 96.5% specificity, and 92% positive predictive value (PPV); and percentage SI drop greater than 29% had 40% sensitivity and 100% specificity for diagnosis of clear cell RCC within the cohort of clear cell RCC, minimal-fat AML, and non-clear cell RCC. A significant proportion of minimal-fat AML (46.2%) displayed homogeneous low T2-weighted SI as opposed to clear cell RCC (5%) and non-clear cell RCC (29%) (p < 0.001).
The percentage SI drop on chemical-shift MRI had high specificity and moderate sensitivity in predicting clear cell RCC over non-clear cell RCC and minimal-fat AML. A percentage SI drop greater than 20% in a renal mass without macroscopically visible fat has high PPV for clear cell RCC over minimal-fat AML and non-clear cell RCC. Among morphologic features, homogeneous low T2 SI favors minimal-fat AML over RCC.
本研究旨在评估化学位移磁共振成像（MRI）在鉴别透明细胞肾细胞癌（RCC）与微脂肪血管平滑肌脂肪瘤（AML）及非透明细胞RCC中的诊断性能。
在这项回顾性研究中，纳入了97例患有实性肾肿瘤且无肉眼可见脂肪、经病理诊断为透明细胞RCC（n = 40）、非透明细胞RCC（n = 31）或微脂肪AML（n = 26）并接受过肾脏化学位移MRI检查的患者。由对病理情况不知情的阅片者记录肿瘤以及对侧正常肾脏在T2加权图像、同相位和反相位图像上的大小、位置、形态和信号强度（SI）。计算肿瘤与肾实质的SI下降百分比（SI下降百分比），并将其与肿瘤组织学进行关联分析。采用Kruskal-Wallis检验、单因素方差分析、卡方检验和Fisher精确检验进行统计学分析。
与非透明细胞RCC和微脂肪AML相比，透明细胞RCC的SI下降百分比显著更高（p < 0.001）。SI下降百分比大于20%时，敏感度为57.5%，特异度为96.5%，阳性预测值（PPV）为92%；在透明细胞RCC、微脂肪AML和非透明细胞RCC队列中，SI下降百分比大于29%时，对透明细胞RCC诊断的敏感度为40%，特异度为100%。与透明细胞RCC（5%）和非透明细胞RCC（29%）相比，相当比例的微脂肪AML（46.2%）在T2加权图像上显示均匀低SI（p < 0.001）。
化学位移MRI上的SI下降百分比在预测透明细胞RCC而非透明细胞RCC和微脂肪AML方面具有高特异度和中等敏感度。在无肉眼可见脂肪的肾肿块中，SI下降百分比大于20%对透明细胞RCC的PPV高于微脂肪AML和非透明细胞RCC。在形态学特征中，均匀低T2 SI提示微脂肪AML而非RCC。
