儿童颅内毛细胞黏液样星形细胞瘤的 MRI表现

MRI characteristics of pilomyxoid astrocytoma

目的：探讨儿童毛细胞黏液样星形细胞瘤（ PMA ）的MRI表现。方法回顾性分析2011年至2013年间经手术病理证实的7例PMA的MRI表现。男3例、女4例；年龄10～32个月，中位年龄21个月。结果肿瘤病灶边界清楚，6例位于下丘脑-视交叉-第三脑室区域，2例累及双侧颞叶，1例合并神经纤维瘤病-Ⅰ型（ NF-Ⅰ）；1例位于基底节区。实性肿块4例，实性伴囊变3例。T1 WI中，液体衰减反转恢复序列（ FLAIR）检查6例，5例呈低信号，1例呈等信号；FSE序列1例，呈低信号。 T2 WI中，FLAIR序列检查3例，1例呈高信号，2例呈等信号；FSE序列5例，4例呈高信号，1例呈等信号。 DWI 6例，4例呈低信号，1例呈等信号，1例呈等低信号。增强后明显强化，4例均匀强化，3例不均匀强化，1例边缘强化，2例瘤内见不规则低信号区。2例脑脊液播散，1例瘤周轻度水肿，4例脑积水。 MRS检查2例，胆碱（Cho）/肌酸（Cr）升高，N-乙酰天冬氨酶（NAA）/Cr降低。结论PMA的MRI表现具有特征性，好发于3岁以下婴幼儿；下丘脑-视交叉-第三脑室区常见，强化方式多样，肿瘤内出血和周围水肿少见，脑脊液播散较常见。

Objective To investigate the MRI features of pilomyxoid astrocytoma （ PMA ） in children.Methods MRI features of seven children with pathologically proven PMA in 2011-2013 were retrospectively analyzed.The ages of the patients ranged from 10 months to 32 months at initial diagnosis.Results All tumors were well-circumscribed masses.Six tumors were located in the hypothalamic-chiasmatic-third ventricular region , two tumor involved the bilateral temporal lobe , and one tumor was associated with NF-I.One occurred in the basal ganglia region.Four tumors were solid masses , whereas the other three showed cystic components.Six tumors were hypointense and one was isointense on T 1-weighted image.Five tumors were hyperintense and three were isointense on T 2-weighted image.Four tumors were hypointense , one was iso-hypointense and one was isointense on DWI.After contrast administration , four tumors enhanced homogenously and three tumors enhanced heterogeneously , with intratumoral irregular hypointense region in two tumors and rim enhancement in one tumor.Cerebrospinal fluid （ CSF ） dissemination, hydrocephalus and peritumor edema were observed in 2, 4 and 1 of cases, respectively.Proton magnetic resonance spectrum of two PMA showed elevated Cho /Cr ratios and decreased NAA/Cr ratios.Conclusions The imaging features of pilomyxoid astrocytoma include common origination from the midline of the neuroaxis in younger children about 2-3 years old.The CSF dissemination is common.The presence of hemorrhage and peritumor edema is not common.