颅内不典型生殖细胞瘤MRI表现

The Magnetic Resonance Imaging Features of Atypical Intracranial Germinoma

目的探讨颅内不典型生殖细胞瘤MRI特征。方法搜集2009年7月至2016年3月经本院病理证实或诊断性放射治疗证实的20例颅内不典型生殖细胞瘤患者MRI资料。所有患者均行常规MRI检查,其中4例患者行磁共振波谱(MRS)、3例行磁共振血管成像(MRA)检查。详细分析不同部位的颅内不典型生殖细胞瘤的MRI表现。结果 20例患者,男18例,女2例,平均年龄(14±0.4)岁,发病部位依次为基底节区9例、侧脑室4例、左侧额叶3例、脑干2例、下丘脑-垂体2例。不同部位肿瘤的MRI表现不一:基底节生殖细胞瘤囊变出血多见,轻中度不均匀强化,5例出现不同程度脑萎缩,表现为同侧脑沟增宽、脑室扩大及同侧中脑大脑脚变细,其中3例行MRA检查,2例表现为同侧大脑中动脉分支稀疏;侧脑室生殖细胞瘤出血多见;脑干生殖细胞瘤以囊变为主,呈环形强化;额叶生殖细胞瘤MRI表现多样,可呈实性或囊变;下丘脑-垂体生殖细胞瘤表现为垂体柄增粗、垂体增大。4例患者MRS显示病变区域N-乙酰天门冬氨酸(NAA)峰、肌酸(Cr)峰降低,胆碱(Cho)峰降低或升高,均出现乳酸(Lac)峰。4例患者合并松果体区结节,5例患者合并垂体柄结节。结论不同部位的颅内不典型生殖细胞瘤具有不同的MRI表现,掌握各种部位肿瘤的MRI特征,有利于提高不典型生殖细胞瘤的诊断率,从而指导临床选择合适的诊疗方案。

Objective To retrospectively analyse the magnetic resonance imaging（ MRI） features of atypical intracranial germinoma and improve the diagnostic accuracy rate. Methods We collected 20 patients who were diagnosed by diagnostic imaging. All of them received routine MRI scanning,4 of them underwent magnetic resonance spectroscopy（ MRS）and 3 patients had magnetic resonance angiography（ MRA） done. MRI features of intracranial atypical germ cell tumors in different locations were analyzed in detail. Results Total 20 patients（ 18 male： 2 female,14 ＋ 0. 4 years old） were collected. The locations of lesions were 9 cases（ 45%） in the basal ganglia region,4 cases in the lateral ventricles（ 20%）,3 cases（ 15%） in the left frontal lobe,2 cases in the hypothalamus or pituitary（ 10%）,and 2 cases（ 10%） in the brain stem. Most of the basal ganglia germinoma displayed cystic degeneration and hemorrhage,mild to moderate inhomogeneous enhancement after Gd-PA injection. 5 cases with different degree of brain atrophy,which manifested as ipsilateral cerebral sulcus widening,enlarged ventricles and thinning of the ipsilateral cerebral peduncle. Magnetic resonance angiography（ MRA） was performed in 3 cases; 2 cases showed ipsilateral sparse cerebral arterial branches. Hemorrhage was common in the lateral ventricle germinomas. Brainstem germinomas was showed cystic degeneration and rim enhancement. The MRI manifestations of frontal lobe germinoma lacked specificity. The 4 cases underwent magnetic resonance spectroscopy（ MRS）showed lesions of N-acetylaspartate（ NAA） and decreased creatine（ Cr） peak,while the choline（ Cho） peak was either decreased or increased; Lactic acid（ Lac） peak was found in all of lesions. Pineal region nodule was found in 4 patients and pituitary stalk thickening was exhibited in 5 patients. Conclusion Atypical germinomas located in different position have different MRI features. MRI studies can improve the accuracy of diagnosis before surgery and guide the selection of proper treatment scheme.