肾脏上皮样血管平滑肌脂肪瘤的CT及MRI表现

CT and MRI features of renal epithelioid angiomyolipoma

目的探讨肾脏上皮样血管平滑肌脂肪瘤的影像学特点，以提高其诊断水平。方法搜集经手术病理证实的26例肾脏上皮样血管平滑肌脂肪瘤（EAML）患者的影像学资料并进行回顾性分析。26例患者均未合并结节性硬化症。16例行CT检查，18例行MRI检查。结果26例患者病灶最大径为0．9～16-3cm，平均7．3cm。病灶呈类圆形或类椭圆形20例（77．0％），分叶状4例（15．4％），沿肾周间隙铸型生长1例（3．8％），不规则形1例（3．8％）；病灶完全位于肾轮廓之内2例（7．7％），部分突出于肾轮廓外24例（92．3％），其中以窄蒂状与肾实质相连2例（7.7％）；2例（7．7％）肿瘤侵犯肾静脉形成静脉瘤栓；1例（318％）同时发现腹膜后淋巴结转移；1例（3．8％）同期发现肝脏和肺多发转移。12例CT平扫示9例（75．0％）呈高或梢高密度，2例（16．7％）呈等．低或低密度，1例（8．3％）呈等-高密度。18例MRl平扫T1W图像15例（83．3％）病灶以等信号为主，T2W或T2W／FS图像10例（55．6％）病灶以低信号为主，8例（44．4％）呈低-高、低-等或低-等、高混杂信号。双期增强CT和／或动态MRI增强扫描示25例（100％）均呈不均匀强化，其中10例（40％）呈网格样强化，23例（92．0％）病灶动脉期强化程度呈等或略低于正常肾皮质，实质期强化程度均低于正常肾实质。1例（3．8％）病灶内见弯曲条带状钙化；9例（34．6％）可观察到少量脂肪成分；8例（30．8％）病灶内见扩张或粗大迂曲走行的血管；8例（30．8％）瘤内伴有出血。结论肾脏EAML影像学表现具有如下特征：女性多见；多呈类圆形或膨胀性生长；肿瘤较大时可出现囊变及出血；病灶内成熟脂肪成分并不多见；钙化罕见：肿瘤实性成分CT平扫呈梢高或高密度；T2WI呈梢低信号或高低混杂信号；动态增强扫描多数呈“快进快出”的强化特点，不均匀筛网状强化较多见；部分病灶内可见迂曲扩张血管：可以伴有局部淋巴结及远处转移。

Objective To analyze the MRt and CT features of renal epithelioid angiomyolipoma （EAML）. Method The imaging data of 26 patients who were surgically and pathologically diagnosed as EAML were analyzed. None of the patients had a history of tuberous sclerosis complex. Before operation, 16 patients underw＇ent CT examination, and 18 patients underwent MRI examination. Result The diameter of lesions ranged from 0.9 to 16.3 cm （mean 7.3 cm）. 20 （77.0%） lesions appeared as round or oval, 4 （15.4%） were lobulated, I （3.8%） showed a restricted growth pattern, and another one （3.8%） was irregular; 24 cases （92.3%） showed exophytic masses, and in which 2 were with narrow pedicles; In addition, 2 lesions （7.7%） were within kidney contours. In 2 cases （7.7%）, tumor thrombus was seen extending into the right renal vein; One patient （3.8%） had a para-caval lymph nodes involvement; And one patient （3.8%） had liver metasta- sis and concurrent lung metastasis. On pre-contrast CT scans, 9 lesions （75.0%） appeared as hyperattenuation or slight hy-perattenuation, and two masses （16.7%） were iso-hypodense or hypodense, one lesion （8.3%） showed iso-hyperattenua- tion. Compared with the surrounding normal renal parenchyma, 15 cases （83.3%） presented mainly isointensity on T1W image, and 10 cases （55.6%） presented mainly hypointensity on T2W image or T2W/FS image, and 8 （44.4%） lesions presented iso-hyperintensity, hypo-isointensity, hypo-iso-hyperintensity on T2W image. On contrast CT/MRI scans, 25 lesions （100%） demonstrated inhomogeneous enhancement, and 10 of 25 （40%） masses showed reticular enhancement. 23 masses （92.0%） were similar to the normal renal cortex in the corticomedullary phase, and obviously decreased enhance- ment in the nephrographic phase. Curvilinear bands of calcifications was observed in 1 case （3.8%）; The tortuous and irregular dilation vessels in the lesion were detected in 8 cases （30.8%） and bleeding was found in 8 cases （30.8%）. Conclu- sion The imaging characteristics of EAML include： Most EAML patients were women; EAML showed round or oval and exophytic mass; The larger mass can be accompanied by necrosis and hemorrhage; Mature fat can be found in few tumors; Calcification is rare; The solid portion of tumor presented slight hyperattenuation or hyperattenuation in unenhanced CT, hypointensity or hyper-hypointensity mixed signal intensity on T2W images and inhomogeneous enhance- ment （rapid wash-in and rapid wash-out）; Reticular enhancement was more common; The tortuous and irregular dilation vessels were found in some lesions; Some patients had local lymph node involvement and distant metastasis.