中枢神经系统黑色素瘤的MRI表现

MRI Appearance of malignant melanoma in central nervous system

目的:探讨中枢神经系统黑色素瘤的影像表现,以期提高认识。方法:搜集经手术病理证实的中枢神经系统黑色素瘤8例,对其影像学表现进行分析。8例均行MRI平扫和增强扫描,7例行扩散加权成像(DWI)扫描,4例行氢质子磁共振波谱(1 H-MRS)扫描,2例行磁共振灌注(PWI)扫描。结果:8例患者原发2例,分别位于脑膜以及脊膜;转移6例,均位于脑内,多接近脑表面。信号表现:典型的黑色素瘤3例,T1WI呈高信号、T2WI呈低信号,增强扫描明显强化,不典型黑色素瘤5例,信号表现多样,部分出现囊变坏死,增强扫描实性部分明显强化。DWI示除2例多发转移者表现为低信号外,其余5例均表现为高信号或混杂高信号。1 H-MRS表现:原发于脑膜者胆碱(Cho)峰明显增高,N-乙酰天门冬氨酸(NAA)峰缺失,并出现高耸的脂质(Lip)峰;3例脑内单发转移者Cho峰明显升高,NAA峰减低,出现不同程度升高的Lip峰。PWI表现:2例行灌注成像者均表现为高灌注。结论:中枢神经系统黑色素细胞肿瘤影像表现多样,与其黑色素含量、瘤内出血及坏死密切相关,综合分析临床和影像资料有助于提高诊断的准确性。

Objective：To investigate the MRI features of malignant melanoma in central nervous system（CNS）for improving our understanding.Methods：A total of 8cases of pathologically proved CNS malignant melanoma were included in this study.All 8cases underwent MRI with and without enhancement.Of these 8cases,7with DWI images,4with 1 HMRS,and 2with PWI images.Results：Of the 8cases of CNS malignant melanoma,2cases were primary,which were located in meninges of brain and spine respectively.6cases were metastatic,which were all located in the brain and near the cerebral surface.Three typical cases of melanoma showed hyper-intensity on T1 WI,hypo-intensity on T2 WI,and obvious enhancement.The other atypical 5cases showed varied MRI signal intensities.Some cases had cystic degeneration and necrosis.The solid component showed marked enhancement.On DWI images,5cases showed hyper-intensity or mixed signal intensity with primarily hyper-intensity,2cases showed hypo-intensity.On 1 H-MRS,the cases originated from meninges showed obviously increased Cho peak,lack of NAA peak,and obvious increased Lip peak.Three cases with single cerebral metastasis of malignant melanoma showed obviously increased Cho peak,decreased NAA peak,and increased Lip peak with different degrees.Two cases underwent PWI,both showed hyper-perfusion.Conclusion：The imaging manifestations of malignant melanomas in CNS are various,which are closely related to the component of melanin,the presence of hemorrhage and/or necrosis in the tumor.Comprehensive analysis of clinical data and imaging findings may help to improve the diagnostic accuracy of malignant melanoma in CNS.