低级别星形细胞瘤的MRI诊断

目的 探讨低级别胶质瘤的MR影像特征及其鉴别诊断.方法 回顾分析21例经病理证实的Ⅰ～Ⅱ级星形细胞瘤的MRI表现.结果 21例低级别星形细胞瘤中,毛细胞星形细胞瘤（PA）5例,2例位于小脑蚓部,额叶、颞叶及桥脑各1例;2例多形性黄色星形细胞瘤（PXA）,1例位于颞叶,1例位于额叶.4例PA与2例PXA均表现为囊实性或囊性伴实性结节,增强扫描实性部分或实性结节明显强化,囊性部分无强化,1例PA囊壁可见轻度强化,其余病变囊壁均无强化.1例桥脑PA病变为实性弥漫生长,增强扫描仅部分轻度强化.14例弥漫性星形细胞瘤,额叶7例,颞叶3例,顶叶2例,桥脑2例,其中无明确肿块且边界不清的8例,有明显肿块的6例,表现为等、长T1和长T2信号,增强扫描除1例桥脑弥漫病变可见轻度斑片状强化外,其余病变均无明显强化.结论 低级别星形细胞瘤的MRI表现有一定的特征性,结合临床资料综合分析,有利于提高肿瘤的诊确率.

MRI diagnosis of low-grade astrocytoma

Objective To investigate the Magnetic resonance imaging （MRI） features and differential diagnosis of low grade astrocytoma.Methods MRI findings were retrospectively reviewed in 21 patients with grade Ⅰ and grade Ⅱ astrocytoma proved by pathology.Results Of the 21 patients,5 were found with pilocytic astrocytoma （PA）,of which 2 cases were located in cerebellar vermis,with one case in the frontal lobe,temporal lobe and the pons each.Two patients of pleomorphic xantho astrocytoma （PXA） were found,of which one was located in the temporal lobe and one was located in the frontal lobe.Four patients of PA and 2 patients of PXA showed solid-cystic or cystic with mural nodule.After injection of contrast media,the solid part or mural nodule enhanced markedly.The cystic wall showed slight enhancement in one patient of PA,with no enhancement in other PA patients.One case of PA in pons showed diffuse growth of solid mass,with slight enhancement.Fourteen patients with diffuse astrocytoma were found,including 7 cases of frontal,3 cases of temporal lobe,2 cases of parietal lobe,2 cases of pons.Of the 14 cases,8 had no clear mass and without clear bump,6 had clear masses.The tumors showed isointensity or low signal on T1WI and high signal on T2WI in all 14 cases.The lesions showed no enhancement except one in pons showed slight patchy enhancement.Conclusion MRI findings of low grade astrocytoma has certain characteristics.It can improve the accuracy of diagnosis when combined with clinical data.