肝脏乏脂肪型血管平滑肌脂肪瘤的CT诊断

CT diagnosis of hepatic angiomyolipoma with minimal fat type

目的探讨肝脏乏脂肪型血管平滑肌脂肪瘤(mHAML)的CT诊断及其鉴别诊断,提高对肝脏不典型占位病变的认识。方法选择5例经手术或穿刺活检证实的mHAML,均行CT平扫及三期动态增强扫描,分析薄层轴位及最大密度投影(MIP)重组图像CT表现。结果 5例均为肝内单发病灶,边界清晰,CT平扫呈均匀稍低密度,未测得脂肪密度。5例CT增强动脉期均呈全瘤欠均匀明显强化,其中3例门脉期及延迟期持续强化高于周围肝实质密度,时间-密度曲线呈"速升缓降"改变;2例门脉期强化密度迅速减低,呈"速升速降"表现。5例病灶动脉期薄层及MIP重组图像显示中央均可见迂曲粗大点、条状血管影,其中1例病灶周边见动脉期提早显示引流肝静脉影。病理组织学示5例病灶内主要含血管和平滑肌成分,脂肪含量极少(<10%)。结论 mHAML CT动态增强扫描强化特征与其他富血供病变类似,导致鉴别诊断困难。多排螺旋CT(MDCT)薄层及MIP重组技术对鉴别诊断有重要价值。无肝炎病史、肝硬化背景,AFP正常,肝内病灶无包膜,动脉期其中央出现迂曲粗大点、条状血管影伴或不伴病灶周边引流肝静脉早期显影者,提示mHAML可能。

Objective To discuss CT sign of hepatic angiomyolipoma with minimal fat type（mHAML）.To improve diagnosis on the atypical occupying lesions of hepatic.Methods 5 cases of mHAML were confirmed by operation or biopsy.CT scan and three phase dynamic enhanced scan were conducted in these cases.The thin axial and maximum intensity projection（MIP）recombinant CT image were analyzed.Results The 5 cases of hepatic single lesion showed clear boundary and CT scan showed homogeneously low density.The fat density was not available.5 cases of CT enhancement on arterial phase and the aneurysm were under homoge-neous enhancement;for 3 out of these 5 cases,the portal and delayed phase strengthened is still higher than the surrounding liver parenchyma density.Time-density curve changed by“rise fast and drop slow”pattern;for 2 cases,the portal phase density rapidly reduced and showed a“rise fast and drop fast”pattern.The lesion during arterial phase TLC and MIP recombinant image for 5 cases displayed the visible tortuous large point bar,vas-cular shadow and 1 cases among them showed early drainage of the hepatic vein at peripheral.Pathology showed that the lesions mainly consisted of smooth muscle and vascular elements,while fat content is ex-tremely low（〈1 0%）.Conclusion The features for the CT enhanced scan of hepatic angiomyolipoma with minimal fat resembled that of other hypervascular lesions,thus caused difficulties in differential diagnosis. MDCT layer and MIP recombination technology are of important value in diagnosis and differential diagnosis. If the dynamic enhanced scan for a patient without a history of hepatitis,cirrhosis,normal AFP or capsular of intrahepatic lesions shows that circuity bulky points and strips of vascular shadow appear on the central part of the arterial phase with or without early development of hepatic vein in lesions peripheral drainage,a possible mHAML should be considered.