四肢外周原始神经外胚层肿瘤的MRI表现及ADC值诊断价值

MRI of Peripheral Primitive Neuroectodermal Tumor in Limbs and Diagnostic Value of ADC Values

目的探讨四肢外周原始神经外胚层肿瘤（p PNETs）的MRI特征表现及表观扩散系数（ADC）值的诊断意义。方法回顾性分析25例经病理证实的四肢处p PNETs的临床、病理及影像学资料。结果 25例p PNETs患者中,单发21例,多发4例。T1WI上18例表现为稍低或低信号,T2WI及T2WI抑脂序列上23例表现为混杂高信号。19例病灶侵犯周围骨质,其中5例出现骨膜反应。23例病灶与周围软组织分界不清,其中4例可见神经血管包绕。所有病灶扩散加权成像（DWI）高b值扩散均受限,ADC值为（0.57±0.03）×10^-3mm^2/s,95%的置信区间为0.51~0.62,平均r ADC值为0.383±0.016,95%的置信区间为0.35~0.42。增强扫描16例表现为明显不均匀强化。结论四肢p PNETs表现有一定特征,平扫表现为稍长或长T1、混杂长T2信号,增强扫描明显不均匀强化,具有侵袭性。ADC值低于一般恶性肿瘤。

Objective To investigate MRI features of peripheral primitive neuroectodermal tumor（p PNETs） in limbs and diagnostic value of ADC value.Methods 25 patients with p PNETs proved by histology were retrospectively reviewed.The clinical,pathological and radiological data were analyzed.Results Among 25 patients with p PNETs,Single lesion existed in 21 patients and 4 patients had Multiple lesions.72% lesions（18/25） showed hypointensity or slight hypointensity on T1 WI,92%（23/25） lesions were characterized by mixed hyperintensity T2 WI.76%（19/25） lesions had different degree of bone destruction.5 patients had periosteal reaction.The margin of 92%（23/25） lesions was ill-defined,the tumor wrapped around the nerve and blood vessels in 4 lesions.All lesions on high b values of DWI showed restricted diffusion and ADC value was（0.57 ± 0.03） × 10^-3 mm^2/s,95% confidence interval was0.51-0.62,r ADC value was 0.383 ± 0.016.95%confidence interval was0.35-0.42.After injection of contrast agent,80%（16/20） lesions showed obvious inhomogeneous enhancement.Conclusion MR imaging of p PNETs had certain characteristics.It showed hypointensity or slight hypointensity on T1 WI,and mixed hyperintensity on T2 WI.Contrast enhanced MRI showed obvious inhomogeneous enhancement,The tumor＇s ADC value is lower than general malignant tumor.