A study of proton MR spectroscopy in patients with minimal hepatic encephalopathy / 中华放射学杂志

ABSTRACT

Objective To evaluate changes of regional cerebral metabolism by proton MR spectroscopy (~1H-MRS) in patients with minimal hepatic encephalopathy (MHE) and to correlate these changes with the neuropsychological test. Methods Fifty-four patients with cirrhosis including nine patients with hepatic encephalopathy (HE),23 patients with MHE,22 patients without HE and 13 controls underwent neuropsychological tests and ~1H-MRS scanning. The volumes of interest included occipital gray matter and left parietal white matter regions. Ratio of spectral peak areas of N-acetylaspartate (NAA),choline (Cho),myo-inositol (mI),and glutamine/glutamate (Glx) relative to creatine (Cr) were acquired. Statistical analysis was conducted using independent t test and one-way analysis of variance. The results of different groups were compared by using the nonparametric Mann-Whitney U test with Bonferroni correction. Correlations among the ~1H-MRS ratios, the grade of HE, neuropsychological test and ammonia data were calculated with Spearman correlation test. Results The ratios of NAA/Cr,Cho/Cr,mI/Cr,Glx/Cr of the occipital gray matter and left parietal white matter regions in patients with cirrhosis are 1.55±0.12,0.48±0.10,0.42±0.14,2.52±0.48 and 1.73±0.17,0.75±0.16,0.42±0.16,2.75±0.59respectively,and they are 1.53±0.10,0.48±0.09,0.51±0.11,2.20±0.39 and 1.69±0.15,0.82±0.14,0.53±0.12,2.40±0.40 in patients without HE,1.58±0.13,0.48±0.08,0.38±0.13,2.62±0.39 and 1.78±0.18,0.74±0.14,0.38±0.15,2.84±0.58 in patients with MHE,1.54±0.12,0.50±0.13,0.29±0.07,3.04±0.31 and 1.70±0.19,0.62±0.16,0.29±0.07,3.37±0.38 inpatients with HE.Compared with controls, decreased mI/Cr and Cho/Cr ratios and elevated Glx/Cr ratios were found in patients with cirrhosis (t=3.196,9.394,-6.527,P＜0.01,occipital gray matter. t=5.592,9.717,-6.681,P＜0.01,left parietal white matter＝ and in subgroup of patients without HE, with MHE and HE (F=5.097,25.896,20.204,P＜0.01,occipital gray matter.F=16.435,28.660,21.283,P＜0.01,left parietal white matter).Significant difference in these metabolic alterations was also found among the different groups of cirrhosis especially the ratios of Glx/Cr in occipital gray matter and left parietal white matter (P＜0.0084).The ratios of mI/Cr also significantly altered between patients without HE and with MHE (P＜0.0084).There was a significant negative correlation between the ratios of Cho/Cr,mI/Cr and the grade of HE (P＜0.01＝ and a significant positive correlation between the ratios of Glx/Cr and the grade of HE (r=0.709,P＜0.01,occipital gray matter; r=0.720,P＜0.01,left parietal white matter＝.NCT-A and DST of controls is (49±8) s and 39±6.They are (134±37),(83±26),(64±22) second and 15±2,25±9,35±8 in patients with HE,MHE and without HE respectively.The metabolic alterations of Cho/Cr,mI/Cr,Glx/Cr correlated significantly with neurepsychological tests in all subjects (P＜0.01＝.There was a significant positive and a negative correlation between the ratios of Glx/Cr and the data of NCT-A and DST respectively (r=0.570,-0.642,occipital gray matter; r=0.541,-0.632,left parietal white matter).The metabolic alterations of Glx/Cr had no correlation with ammonia data as well as other metabolic alterations.Conclusions ~1H-MRS study shows cerebral metabolic alterations of gray and white matter in patients with cirrhosis,especially the reduction in mI/Cr ratio and increase in Glx/Cr ratio. These changes correlate well with the neuropsychological tests and may be useful in predicting the presence of MHE.