轻微型肝性脑病的~1H-MRS和磁共振弥散张量成像研究

目的 探讨氢质子波谱(~1H-MRS)及弥散张量成像(DTI)在预测轻微型肝性脑病(MHE)中的价值.方法 29例肝硬化患者及14例年龄相匹配的健康对照者分别进行头部MRS与DTI扫描,其中15例患有MHE(经数字连接试验及数字符号试验测试).采用单体素激励回波采集序列(STEAM)行左侧基底节区MRS扫描,分别计算N-乙酰天门冬氨酸(NAA),肌酸(Cr),胆碱(Cho),肌醇(mIns),谷氨酰胺复合物(Glx)的峰下面积.并计算各自与Cr比值:NAA/Cr、Cho/Cr、mIns/Cr、Glx/Cr.DTI选用平均弥散率(MD)及各向异性分数(FA)作为参数,选取主要的白质及深部灰质共7个部位为感兴趣区,计算各部位MD及FA值.结果 MRS检查结果显示各组间NAA/Cr与Glx/Cr无显著性差异(P＞0.05),MHE组mIns/Cr与Cho/Cr降低,与无MHE组及对照组间有显著性差异(P＜0.05).而无MHE组与正常对照组间mIns/Cr与Cho/Cr无显著性差异(P＞0.05).DTI检查结果发现有与无MHE的肝硬化患者及对照组不同部位MD值间差异有统计学意义(P＜0.05);FA值无显著性差异(P＞0.05).与对照组比较,MHE组脑内5个部位的MD值显著性增加(P＜0.05);无MHE的肝硬化组仅在尾状核部MD值显著增加(P＜0.05).结论 MHE病人基底节区显示的代谢物改变以及脑内MD值增高不伴FA值的异常改变,提示MHE病人存在轻度细胞外间隙脑水肿,MRS及DTI在预测MHE中有一定价值.

~1H-MRS and Diffusion Tensor Imaging Study in Minimal Hepatic Encephalopathy

Objective To evaluate the value of proton magnetic resonance spectroscopy(~1H-MRS))and diffusion tensor imaging(DTI)in minimal hepatic encephalopathy(MHE).Methods Twenty-nine with cirrhosis(15 cases with MHE diagnosed according to number-connection test A and digital symbol test and 14 age-matched controls underwent ~1H-MRS and DTI examinations.~1H-MRS of left basal ganglia were acquired using STEAM sequences.Peak area of each metabolite,including NAA,Cr,Cho,mIns and Glx and their ratios to Cr were measured,respectively.Fractional anisotropy(FA),mean diffusivity(MD)were calculated in deep gray matter nuclei and mainly white matter regions in both cerebral hemispheres.The MD and FA values from different regions in different groups were compared.Results NAA/Cr and Glx/Cr levels showed no significant difference among the groups(P＞0.05).Ratios of mIns/Cr and Cho/Cr showed no differences in MHE group compared to controls(P＞0.05),whereas were significantly different in MHE and cirrhosis without MHE(P＜0.05).The MD values from different regions had a significant difference among various groups(P＜0.05),and there were no significant changes in FA among the groups(P＞0.05).Significantly increased MD was found in five regions of brain in MHE and only caudate nuclei in cirrhosis without MHE compared to controls.Conclusion Patients with MHE have abnormal metabolite changes in basal ganglia;the increase in MD with no concomitant changes in FA in cirrhosis with MHE that indicates the presence of reversible interstitial brain edema.MRS and DTI may be sensitive tests for detecting MHE.