| ObjectiveTo investigate abnormal metabolism in injured refrontal cortex and hippocampus of heroin addicts with 1H magnetic resonance spectroscopy(MRS).As the proton MRS water chemical shift depends approximately linearly on temperature,we measured the absolute temperature in prefrontal cortex and hippocampus of heroin addicts with relevant proven equation conversion,which reflect the micro pathological changes exist in addictive brain area,to explore its feasibility and significance in assessment of drug addiction and craving.Methods24 male heroin addicts in the withdrawal state(time of withdrawal therapy is 2-6 months)were selected as the experimental group,and 24 male healthy volunteers whose age and education time matched with the experimental group were selected as the control group.All subjects underwent routine axial T2WI,FLAIR scans and single voxel MRS scan of prefrontal cortex(regions of interest including the left and right cortex)and bilateral hippocampus.The experimental group received repeated MRS scans continuously in the resting state and visual stimulation state(subjects were asked to carefully watch the heroin-related cue images to induced craving state),in addition,the position/volume of the region of interest and scanning parameters were consistent completely between two scans.The spectral images were analysis,then measured and recorded N-acetylaspartate(NAA)/creatine(Cr)ratio and NAA chemical shift value of the prefrontal cortex and bilateral hippocampus from all subjects.Taking NAA as reference and according to the relationship between the brain temperature(T)and NAA chemical shift(CSNAA):T=37+100(CSNAA-2.035),the absolute temperature of prefrontal cortex and hippocampus were calculated from all subjects.NAA/Cr value,brain temperature were statistically analyzed.Results1.There was no abnormal signal lesions and structural abnormality in the brain of heroin dependent group and control group in the conventional MRI.MRS of prefrontal cortex and bilateral hippocampus showed stable baseline and legible metabolites peak.2.Comparison of heroin dependence group resting state and control group:the NAA/Cr value of prefrontal cortex and left hippocampus in heroin addicts were lower than the normal control group,the difference was statistically significant(P<0.05),but the NAA/Cr value of the right hippocampus showed no significant difference between two groups(P>0.05).3.Comparison resting state and visual stimuli state of heroin dependence group:there were no significant temperature difference between the two states in prefrontal cortex and bilateral hippocampus(P>0.05).4.Comparison of heroin dependence group resting state and control group:the temperature of the prefrontal cortex in heroin dependent group was significantly higher than that in the control group(P<0.05).There was no significant temperature difference in bilateral hippocampus between the two groups(P>0.05).5.Linear correlation and regression analysis were made between total amount of heroin consumption and NAA/Cr,temperature,temperature difference(△T)of heroin dependent group in three regions.We found the prefrontal cortex temperature of heroin dependence group resting state and total amount of heroin consumption had a linear positive correlation(P<0.05),the coefficient of determination(R Square R2)is 0.225,ConclusionThe conventional MRI has a great limitation on detection of the microscopic pathological changes of brain injury induced by heroin.however,1H MRS can be used to display and evaluate the changes of neurons and metabolism in the corresponding brain regions caused by the early heroin toxicity.The changes of NAA content reflected the number,density and functional status of neurons,while the NAA chemical shift values could be used to measure the temperature changes in related dependent regions of patients with drug abuse.Frontal lobe is the key and vulnerable brain region of heroin addiction,and the increase of the temperature in the prefrontal cortex of resting state may be a comprehensive reflection of the changes of neuron damage,cerebral blood flow and cerebral metabolism.Although the intrinsic mechanism and influencing factors of brain temperature are complex,it is a potential evaluation index to explore the mechanism of drug dependence,and to evaluate addiction and craving. |
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