少脂肪良性肾脏血管平滑肌脂肪瘤的影像学表现

Imaging findings of benign renal angiomyolipoma with minimal fat content

目的:观察良性少脂肪肾脏血管平滑肌脂肪瘤(AML)的影像学表现。材料和方法:回顾性分析20例(男6例,女14例)经手术及病理证实的良性肾脏少脂肪AML的超声、CT及MRI表现。全部病例均行超声检查。12例行CT平扫及增强,1例仅行CT增强。12例行MR平扫及增强,1例仅行MR平扫。结果:病灶呈扁圆形或不规则形10例(50%),与肾脏交界面平直者9例(45%);15例(75%)病灶突出于肾轮廓外,其中7例(46.7%)呈限制性生长或"蘑菇"征。9例(75%)CT平扫呈均匀稍高密度。全部病灶T2WI信号稍低于肾实质,信号完全均匀4例(30.8%),夹杂微小点片状稍高信号9例(69.2%);双回波化学位移成像5例(41.7%)反相位信号点状或片状减低。双期CT和动态MRI增强扫描示病灶呈均匀或筛网状强化。12例(60%)病灶呈高回声,18例(90%)回声均匀。3例(15%)病灶内见扩张或粗大迂曲走行的血管。结论:良性肾脏少脂肪AML的影像学表现具有以下特征:形态不规则或非膨胀性生长、稍高回声、CT平扫呈稍高密度、T2WI呈均匀稍低信号或夹杂少许点片状稍高信号、均匀或筛网状持续性强化、女性多见、病灶内偶可见迂曲扩张血管等。

Objective：To analyze the imaging findings of benign renal angiomyolipoma（AML） with minimal fat.Materials and Methods：Ultrasonography,CT and MRI findings in 20 patients（6 males,14 females） of benign renal AML with minimal fat confirmed by surgery and pathology were analyzed retrospectively.All patients underwent ultrasonography.Unenhanced and biphasic CT scans were performed in 12 patients,1 patient underwent biphasic CT scan only.Unenhanced and dynamic contrast-enhanced MRI were performed in 12 patients,1 patient underwent unenhanced MRI only.Results：Ten lesions（50%） were of irregular or ellipsoidal shape.The tumor-kidney interface was straight in 9 lesions（45%）.Fifteen lesions protruded from the renal margin,and 7 lesions（46.7%） with restricted growth pattern or ＂fungus sign＂.Compared with the surrounding renal parenchyma,9 lesions（75%） showed homogeneously high attenuation on unenhanced CT images.Of the 13 patients examined with MR imaging,all were hypo-intense on T2WI,homogeneous（4 lesions,30.8%） or with micro hyper-intense spot（9 lesions,69.2%）.On double-echo GRE chemical shift imaging,focal or diffuse signal suppression were found in 5 lesions（41.7%）.All lesions showed homogeneous or reticular enhancement on biphasic CT and dynamic contrast-enhanced MRI images.Twelve lesions（60%） showed hyperechogenicity on ultrasonography,and 18 lesions（90%） were homogeneous.Tortuous and enlarged vessels were found in 3 lesions（15%）.Conclusion：Benign renal AML with minimal fat usually has irregular or nonexpansive growth pattern,homogeneous hyperechogenicity on ultrasonography,homogeneously high attenuation on unenhanced CT images,homogeneously hypointense on T2WI with micro hyperintense spots,homogeneous or reticular prolonged enhance ment on contrast-enhanced CT and MRI images,female predominance,and tortuous or enlarged vessels were found occasionally.