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目的分析肝脏小血管瘤(≤2 cm)的MRI动态增强及扩散成像表现特点,以帮助临床诊断。方法回顾性研究经病理证实的30例患者42个肝脏小血管瘤病灶,根据动态增强特征将其分为典型(Ⅰ型)、高灌注型(Ⅱ型)、非典型(Ⅲ型)三型。分别观测其MRI平扫、动态增强扫描、扩散成像表现并进行定量分析,进而综合评价各型小血管瘤的MRI表现特点及鉴别诊断要点。结果动态增强中,Ⅰ型小血管瘤(21例)各期均呈相对高信号,以缓升缓降型持续强化为主;Ⅱ型小血管瘤(7例)各期均呈相对高信号,以速升缓降型持续强化为主;Ⅲ型小血管瘤(14例)持续呈相对低信号,以低度延迟强化为主。Ⅱ型小血管瘤与门静脉在动态增强各期信噪比无统计学差异,而Ⅰ、Ⅲ型小血管瘤与门静脉间存在统计学差异(P=0.046及P=0.002)。扩散成像中,小血管瘤的信号均明显高于肝实质,但三型间信号无统计学差异;肝小血管瘤总体上具有较肝组织高的表观扩散系数(ADC)值,Ⅱ型平均ADC值高于Ⅰ型及Ⅲ型(P=0.0034)。结论各型肝小血管瘤的MRI表现具有一定特征性,MRI动态增强扫描、扩散成像、ADC值测定等对于肝脏小血管瘤的诊断及鉴别具有重要作用。
Objective To analyze the features of dynamic enhancement and diffusion imaging of small hemangiomas (≤2 cm) in liver to help clinical diagnosis. Methods Forty-two small hemangioma lesions of the liver in 30 patients confirmed by pathology were retrospectively studied. According to their dynamic enhancement features, they were divided into three types: typical type (Ⅰ type), high perfusion type (Ⅱ type) and atypical type Ⅲ. MRI plain scan, dynamic contrast-enhanced scanning and diffusion imaging were performed respectively and quantitatively analyzed. MRI features and differential diagnosis points of various types of small hemangiomas were evaluated comprehensively. In the dynamic enhancement results, all the stages of type 1 small hemangiomas (21 cases) showed relatively high signal, with sustained and slow descending type as the mainstay. Type Ⅱ small hemangiomas (7 cases) showed relatively high signal in all stages, With the type of slow increase and decrease continued to strengthen the main type Ⅲ small hemangioma (14 cases) showed a relatively low signal continued to strengthen the main low-delay. There was no significant difference in the signal-to-noise ratio between type Ⅱ small hemangiomas and portal vein in each stage of dynamic enhancement, while there was a significant difference between type Ⅰ and type Ⅲ small hemangiomas and portal vein (P = 0.046 and P = 0.002). Diffusion imaging, small hemangioma signals were significantly higher than the liver parenchyma, but there was no significant difference between the three types of signals; hepatoma hemangiomas overall higher apparent diffusion coefficient (ADC) values than liver tissue, type Ⅱ average ADC values were higher than those of type I and type III (P = 0.0034). Conclusions MRI findings of various types of hepatic small hemangiomas have certain characteristics. MRI dynamic contrast-enhanced scanning, diffusion imaging and ADC value determination play an important role in the diagnosis and differential diagnosis of hepatic small hemangiomas.