颅脑磁共振T1WI高信号病变影像诊断

The Diagnosis of High Signal Intensity Lesions on T1-weighted Brain MR Imaging

目的:探讨颅脑MRI T1WI高信号病变影像表现,结合文献讨论其发生机制和病理改变。方法:回顾性分析63例颅脑MRI TIWI高信号病变的影像表现,包括脑出血、黑色素瘤、糖尿病脑病、缺血缺氧性脑病、亚急性期脑梗死、颅内囊肿及脂肪瘤。结果:脑出血T1WI以高信号为主,T2WI呈低或高信号,磁敏感加权成像(SWI)呈低信号;黑色素瘤T1WI呈高信号,T2WI呈等或低信号,无灶周水肿;糖尿病脑病可见双侧或单侧基底节区T1WI高信号,T2WI信号正常或轻度降低。脑缺血缺氧性疾病高信号主要位于侧脑室旁白质,弥散加权成像(DWI)呈高信号。亚急性期脑梗死高信号主要位于脑灰质,呈片状或脑回样高信号;颅内囊肿主要见于脑室内和鞍区,T1WI以高信号为主,T2WI呈高或/和低信号。脂肪瘤位于大脑镰旁,压脂像呈低信号。结论:含正铁血红蛋白、黑色素、脂质、蛋白及矿物质病变在T1WI上可呈高信号,熟悉这些病变化学组成及其对T1时间的影响有助于鉴别诊断。

Objective：To investigate the imaging findings of high signal intensity lesions on brain MRI,and discuss its mechanism and pathological changes combined with literature.Method：63 cases of TIWI hyperintense lesions on brain MRI were retrospectively analyzed,including cerebral hemorrhage,melanoma,diabetic encephalopathy, hypoxic ischemic encephalopathy,subacute cerebral infarction,intracranial cysts and lipomas.Result：Cerebral hemorrhage mainly showed high signal intensity on T1WI,low or high signal intensity on T2WI,and low signal intensity on susceptibility weighted imaging（SWI）. Melanoma had high signals on T1WI,equal or low signals on T2WI,no edema around the lesions. The high signals of diabetic encephalopathy were showed on basal ganglia bilaterally or unilaterally, T2WI was normal or slightly reduced signal intensity. Hyperintense lesions of hypoxic-ischemic encephalopathy are mainly located in the periventricular white matter,diffusion-weighted imaging（DWI）showed high signal intensity. Subacute cerebral infarction’s flake or gyrus-like high signal lesions mainly located in gray matter. Intracranial cysts were mainly seen in the ventricle and around the sella,hyperintense on T1WI and hyper or hypo intense on T2WI. Lipoma located in the cerebral falx,fat saturated images showed low signal intensity.Conclusion：Brain lesions which include methemoglobin, melanin,lipid,protein and mineral show high signal intensity on T1WI,familiarity with the effect of chemical composition on T1 signal intensity facilitates the differential diagnosis of these lesions.