原发性脑淋巴瘤的MRI影像特征分析

Feature analysis of MRI in primary brain lymphoma

目的探讨原发性脑淋巴瘤磁共振成像(MRI)表现,总结其特征性表现,以提高其诊断的准确率。方法收集经病理及免疫组化证实的22例原发性中枢神经系统淋巴瘤患者的临床资料,均行MRI平扫及增强检查,其中2例行磁共振波谱成像(MRS)及弥散加权成像(DWI)检查。结果 22例患者中单发20例,多发2例,共有27个病灶,瘤灶多为单发,幕上多见,肿瘤形态多为类圆形肿块或结节,肿瘤直径多为2.0～4.5 cm,瘤周水肿多为轻至中度。MRI平扫显示病灶T1多呈等、低信号,T2呈等、高信号,所有DWI呈明显高信号,增强后病灶呈明显强化,形态为多发节结状、团块状,18例见典型的切迹征或开环征。MRS的2例患者中增强后扫描即出现强化的病灶区均表现为胆碱化合物(Cho)峰升高、N-乙酰天门冬氨酸(NAA)峰下降、出现宽大高耸的脂质(Lip)峰。结论原发性脑淋巴瘤MRI表现具有一定特异性,依据MRI平扫、增强、DWI及MRS的特点,结合临床表现,可以对其作出正确诊断。

Objective To investigate the MRI manifestations of primary central nervous system lymphomas （PCNSL） in pathologically confirmed patients, so as to improve the imaging diagnostic accuracy of PCNSL. Methods The MRI findings of 22 cases of pathologically and immunohistochemically confirmed PCNSL were analyzed retrospectively. All patients were examined by nonenhanced and contrast-enhanced MRI. 2 cases wer performed the magnetic resonance spectroscopy（1H-MRS） and diffu- sion-weighted MRI （DWI-MRI） examination. Results 27 lesions were identified in 22 cases, 20 （90.9%） cases were solitary tu- mor focus and the other 2 cases （9.1% ） present the muhifocal form up to 7 lesions. Lesions mainly located at supratentorial brain. The tumor mostly showed quasi-circular mass or nodule in shape with diameter of 2.0-4.5 cm and most of the peritumoral edema were mild to moderate. On Tl-weighted image （WI）, all the lesions appeared to be isointense and hypointense. On T2WI and FLAIR sequences, the lesions appeared isointense or hyperintense. DW1 demonstrated hyperintense lesions. All the lesions pre- sented obvious homogenous enhancement with little or no edema, 18 typical cases presented ＂open-ring＂ and ＂notch sign＂. Brain MRS in 2 cases showed an elevation of choline peak,lip peak and depressed N-acetylaspartate. Conclusion MRI manifestations of PCNSL has certain specificity. The characteristics of nonenhanced and contrast-enhanced MRI, DWI and MRS combined with the clinical manifestations can make the correct diagnosis in most patients with PCNSL.