肌瘤型肝脏血管平滑肌脂肪瘤的CT和MRI特征

Computed tomography and magnetic resonance imaging features of the myomatous hepatic angiomyolipoma

目的探讨肌瘤型肝脏血管平滑肌脂肪瘤（MHAML）的CT和MRI检查影像学特征。方法采用回顾性横断面研究方法。收集2010年1月至2016年6月第三军医大学西南医院收治的22例MHAML患者的临床病理资料。患者行CT、MRI平扫、增强扫描检查。行手术切除或穿刺肝脏肿瘤后，行病理学检查和免疫组织化学染色检测。观察指标：（1）CT、MRI检查表现。由两名放射科医师独立阅片。（2）两名放射科医师诊断的一致性情况。（3）病理学检查结果。一致性检验采用Kappa检验，K≥0．75为一致性好，k≤0．40为一致性差，0．40〈K〈0．75为一致性一般。结果（1）CT和MRI检查表现：22例患者中，16例仅行CT检查，6例同时行CT和MRI检查。22例患者肿瘤均为单发，呈类圆形：肿瘤部位：肝右叶14例，肝左叶7例，肝尾状叶1例。①CT平扫及增强扫描：22例患者肿瘤均呈低密度：20例患者肿瘤边界清楚，2例边界模糊；22例患者增强扫描动脉期肿瘤均明显强化，其中10例强化特点为快进慢出，12例为快进快出；12例患者增强扫描动脉早期可见肿瘤内引流静脉显示；12例患者肿瘤内见增粗血管走行；16例患者肿瘤周边见环状强化，内有部分血管形成，参与肿瘤血供。②MRI检查：6例患者肿瘤均表现为T1加权成像低信号、T2加权成像高信号；6例患者中，5例肿瘤边界清楚，1例边界模糊；6例患者增强扫描动脉期肿瘤均明显强化，强化特点为快进快出：3例患者增强扫描动脉早期可见肿瘤内引流静脉显示：1例患者肿瘤内见增粗血管走行；5例患者肿瘤周边见持续环状强化，内有部分血管形成；6例患者MRI检查含弥散扫描序列，高b值（b=800s／mm。）肿瘤弥散受限，平均表观弥散系数为1．549×10^-3mm^2／s（1．209×10^-3～1．796×10^-3mm^2／s），肝胆期均为低信号。（2）两名放射科医师诊断的一致性情况：两名放射科医师诊断肿瘤部位、密度、T1和T2加权成像信号、出血、强化方式、增粗血管的一致性好（K=1．00，1．00，1．00，1．00，0．82，0．82，P〈0．05）；诊断肿瘤脂肪、钙化、囊变成分，边界，引流静脉，周边强化的一致性一般（K=0．46，0．45，0．64，0．54，P〈0．05）。（3）病理学检查结果：22例患者中，17例行手术切除、5例行穿刺肝脏肿瘤病理学检查结果显示：肿瘤均以平滑肌细胞成分为主，12例见厚壁血管。免疫组织化学染色检测结果显示：22例患者抗黑色素瘤特异性单克隆抗体均为阳性。结论肿瘤周边持续强化、增强扫描动脉早期肿瘤内引流静脉显示、肿瘤内穿插增粗血管对MHAML的CT和MRI诊断有一定提示作用。

Objective To investigate the computed tomography （CT） and magnetic resonance imaging （MRI） features of the myomatous hepatic angiomyolipoma （MHAML）. Methods The retrospective cross-setional study was conducted. The clinicopathological data of 22 patients with MHAML who were admitted to the Southwest Hospital of the Third Military Medical University between January 2010 and June 2016 were collected. Patients underwent plain and enhanced scans of CT and MRI, and then received pathological examination after surgical resection or liver puncture and immunohistochemical staining. Observation indicators ： （ 1 ） findings of CT and MRI, 2 radiologists independently read films; （2） diagnostic consistency of 2 radiologists; （3） results of pathological examination. The Kappa test was used for evaluating the consistency, K≥ 0.75 as a good consistency, 0.40〈〈0.75 as a normal consistency and K≤0.40 as a poor consistency. Results （1） Findings of CT and MRI： of 22 patients, 16 received CT scans and 6 received CT and MRI scans. Tumors of 22 patients were single lesion, showing similar-circular type. Tumors located in the right liver lobe, left liver lobe and caudate lobe were respectively detected in 14, 7 and 1 patients. ① Plain and enhanced scans of CT： tumors of 22 patients showed low density. Twenty patients had clear boundary of tumor and 2 had an unclear boundary. Tumors of 22 patients demonstrated obvious enhancement in arterial phase by enhanced scans of CT, including fast-in and slow-out enhancement in 10 patients and fast-in and fast-out enhancement in 12 patients. The draining veins inside tumors were detected in 12 patients in early arterial phase by enhanced scans of CT. The dilated blood vessels inside tumors were found in 12 patients. The ring enhancement of tumor margin was detected in 16 patients, with formation of small blood vessels involving tumor blood supply. ② MRI scan ： tumors of 6 patients presented as low signal on TI WI and high signal on T2WI. Of 6 patients, 5 had clear boundary of tumor and 1 had an unclear boundary. Tumors of 6 patients demonstrated obvious enhancement in arterial phase by enhanced scans of MRI, with a fast-in and fast-out enhancement. The draining veins inside tumors were detected in 3 patients in early arterial phase by enhanced scans of MRI. The dilated blood vessels inside tumors were found in 1 patient. The persistent ring enhancement of tumor margin was detected in 5 patients, with formation of small blood vessels. All the lesions of 6 patients using GD-EOB-DTPA MR contrast-enhanced scan demonstrated restricted diffusion with a high b value （ b= 800 s/mm2） , an average apparent diffusion coefficient of 1.549×10^-3mm^2/s （ 1. 209×10^-3- 1.796×10^-3 mm^2/s） and low a signal in liver phase. （2） Diagnostic consistency of 2 radiologists： there were good diagnostic consistencies of 2 radiologists in tumor location, density, T1WI, T2WI, bleeding, enhancement method and dilated blood vessels （K = 1.00, 1.00, 1.00, 1.00, 0. 82, 0. 82, P〈0.05）. There were normal diagnostic consistencies of 2 radiologists in tumor fat, calcification, component of eystolization, boundary, draining veins and enhancement of tumor margin （ K = 0.46, 0.45, 0.64, 0.54, P〈0.05）. （3） Results of pathological examination ： results of pathological examination of tumors from surgical resection of 17 patients and liver puncture of 5 patients showed that smooth muscle cells were the major components, and thick-walled vessels were found in the tumor of 12 patients. Results of immunohistochemieal staining showed that anti melanoma specific monoelonal antibody （HMB-45） was positive. Conehlsion The persistent enhancement of tumor margin, draining veins in early arterial phase by enhanced scans and dilated blood vessels might play roles in diagnosis of MHAML.