3T磁共振波谱分析在轻微型肝性脑病诊断中的应用

Application of 3T proton magnetic resonance spectroscopy in diagnosis of minimal hepatic encephalopathy

目的研究3T场强磁共振MRS对轻微型肝性脑病(MHE)患者的诊断价值。方法对33例MHE患者和46例无轻微型肝性脑病的肝硬化患者采用单体素点分辨自旋回波波谱序列进行扣带回和右侧前额叶的MRS扫描。计算N-乙酰天门冬氨酸(NAA)、肌酐(Cr)、胆碱(Cho)、肌醇(MI)和谷氨酰胺复合物(Glx)的峰下面积,计算NAA/Cr、Cho/Cr、MI/Cr、Glx/Cr,并与30例健康体检者(正常对照组)比较。33例MHE患者在MRS检查前后1周内进行了静脉血氨水平测定。结果与正常对照组相比,MHE患者扣带回和右侧前额叶的Cho/Cr、MI/Cr显著降低(P值分别<0.01和<0.001),Glx/Cr比值显著升高(P<0.005)。与无MHE的肝硬化患者间Glx/Cr与Cho/Cr有显著性差异(P<0.01,P<0.005),无MHE的肝硬化患者与正常对照组比较MI/Cr有显著性差异(P<0.001)。扣带回与右侧额叶的Glx/Cr比值与血氨浓度呈正相关,Cho/Cr和MI/Cr的比值与血氨浓度呈负相关。结论3T场强磁共振MRS检查显示MHE患者扣带回和右侧前额叶Cho、MI水平降低,Glx水平升高;扣带回与右侧额叶的MRS指标与血氨之间存在相关关系,3T场强磁共振MRS对MHE的诊断有显著价值;扣带回与右侧前额叶可作为检测肝硬化患者脑改变的敏感部位。

Objective To study the value of proton magnetic resonance spectroscopy （MRS） in diagnosis of minimal hepatic encephalopathy （MHE）. Methods MRS （cingulated cortex and prefrontal lobe） was performed using point-resolved echo spin spectroscopy （PRESS） sequences in 79 patients with hepatic cirrhosis （33 with MHE and 46 without） and 30 controls. Peak area of each metabolite, including NAA, Cr, Cho, MI, Glx and their ratios to Cr were computed, then compared with the controls. Venous ammonia was measured in 33 patients with MHE. Results Compared with the controls, the patients with MHE showed significantly decreased Cho/ Cr, MI/Cr and significantly increased Glx/Cr in the cingulate cortex and the prefrontal lobe. Glx/Cr and Cho/Cr were significantly different in patients without and with MHE （P 〈0.01, P 〈0.005）. MI/Cr was significantly different in patients without MHE from the control group （ P 〈 0. 001 ）. There was a significantly positive correlation between Glx/Cr in the cingulate cortex and the prefrontal lobe and blood ammonia concentration. Cho/Cr and MI/Cr were significantly negatively correlate with blood ammonia concentration. Conclusions MRS showed Cho and MI decreased and Glx increased in the cingnlate cortex and the prefrontal lobe in patients with MHE. There was significant correlation between metabolite changes in the cingulated cortex and the prefrontal lobe and blood ammonia concentration. MRS may be of value in the diagnosis of MHE. The cingulate cortex and the prefrontal lobe might be sensitive location in detecting MHE.