孤立性脑干转移瘤的MRI表现

MRI Findings of Solitary Brain Stem Metastasis

目的分析孤立性脑干转移瘤的MRI表现特征,提高其诊断准确性。方法回顾性分析经病理确诊为脑外肿瘤并经临床诊断为孤立性脑干转移瘤的17例患者的临床资料和MRI表现,分析肿瘤的部位、大小、形态、结构、信号强度、瘤周水肿程度和瘤体的强化特点。结果男8例,女9例,年龄39~69岁,平均55.4岁。脑外原发肿瘤分别为肺癌14例、乳腺癌1例、直肠癌1例、胆囊癌1例。病灶位于桥脑10例、中脑3例、延髓1例、中脑和桥脑2例、桥脑和延髓1例。瘤体最大径〈1 cm者7例,1~3 cm者9例,〉3 cm者1例。8个病灶呈实性,6个呈囊实性,1个呈单纯囊性,2个为囊伴壁结节型。增强扫描病灶呈环状强化9例,结节状强化5例,不规则强化2例,花瓣样强化1例。5例无瘤周水肿,轻度水肿7例,中度水肿3例,重度水肿2例。结论孤立性脑干转移瘤的常规MRI表现缺乏一定的特征性,结合功能MRI及其临床资料有助于与其他病变相鉴别。

Objective To evaluate magnetic resonance imaging（MRI） features of solitary brain stem metastasis so as to promote the diagnostic accuracy.Methods MRI findings of 17 patients with solitary brain stem metastasis diagnosed finally by clinic data combined with extracranial primary malignant tumors proved by pathology were studied retrospectively.The location,size,shape,signal intensity,peritumoral edema as well as findings after contrast enhancement were analyzed.Results Among this group of patients,8 were male and 9 were female.Their ages ranged from 39 to 69 years with an average of 55.4 years.Extracranial primary malignant tumors included lung carcinoma in 14 cases,breast carcinoma in one case,colorectal carcinoma in one case and gallbladder carcinoma in one case.The lesions located in the pons in 10 cases,in the mesencephalon in three cases,in the medulla oblongata in one case,in the pons and mesencephalon in two cases,and in the pons and medulla oblongata in one case.The maximum diameters of the lesions were less than 1 cm in seven cases,between 1 and 3 cm in nine cases,and larger than 3 cm in one case.The MRI findings included solid mass in eight cases,cystic solid mass in six cases,simple cystic mass in one case,and cyst with a mural nodule in two cases.Contrast enhanced MRI showed ring like enhancement in nine lesions,nodular enhancement in five lesions,irregular enhancement in two lesions,and petal like enhancement in one lesion.The peritumoral edema was mild in seven lesions,moderate in three lesions,and severe in two lesion.Conclusion Solitary brain stem metastases have lack characteristic in conventional magnetic resonance imaging（MRI） findings.Combining with the corresponding clinical data and no morphological MR imaging,it will help us to differentiate the metastases from other lesions in brain stem.