鉴别MR T2WI呈等低信号的肾脏肿瘤

Differentiation of renal tumors with iso/hypointensity on T2 MR images

目的分析MR T2WI呈等低信号的肾脏肿瘤的特征。方法回顾性分析72例MR T2WI主要呈等低信号、并经手术病理证实的肾脏肿瘤的资料,对肿瘤大小、形态、坏死、岀血、假包膜、信号、强化程度等进行分析,并对肿瘤的T2信号、T1双回波信号、DWI的ADC值及强化程度等进行定量测量。结果本组病例包括透明细胞肾癌26例,少脂型血管平滑肌脂肪瘤20例,嫌色细胞型肾细胞癌13例,乳头状细胞肾癌7例,嗜酸细胞腺瘤2例,其他少见肿瘤4例。少脂型血管平滑肌脂肪瘤的平均发病年龄低,女性比例高,边界较清楚,假包膜及出血少见。透明细胞肾癌T2信号相对更不均匀,易发生出血,平均ADC值高于其他各组。乳头状细胞肾癌强化程度较低。肿瘤的T2信号、T1双回波信号对肿瘤类型的鉴别未能提供帮助。结论 MR T2WI呈等低信号的不同类型肾肿瘤的影像学征象各有一定特征,综合分析有利于准确判断病变的性质。

Objective To assess the MRI features of renal tumors with iso/hypo^intensity on MR T2WI for characteriza- tion. Methods Seventy-two patients with surgically proved renal tumors showing iso/hypo-intensity on T2WI were retro- spectively evaluated. Tumor size, morphology, extent of necrosis and hemorrhage, pseudocapsule, and signal intensity were assessed qualitatively, while signal intensity of T1 double-echo and T2, ADC value of DWI and extent of enhancement were assessed quantitatively. Results Of all the tumors, there were 26 clear cell renal cell carcinomas （CCRCC）, 20 an- giomyolipomas （AML） with minimal fat, 13 chromophobe renal cell carcinomas （CRCC）, 7 papillary renal cell carcinomas （PRCC）, 2 oncocytomas, and 4 other rare renal tumors. Patients with AML were younger and showing women priority, while the borderline of tumor were clear, with less pseudocapsule and hemorrhage. CCRCC were apt to hemorrhage, and showing higher ADC value with more inhomogeneous signal intensity. PRCC showed the lowest enhancement extent. Sig- nal intensity of T1 double-echo and T2 did not exhibit importance in differentiation. Conclusion Different pathologic types of renal tumor with iso/hypo-intensity on T2WI have different imaging features. Comprehensive analysis of these features provides possibility of correct diagnosis.