| Objective:To study the findings,reason and clinical significance of chronic Pb exposure at brain MRI and 1H-MRS.To provide the scientific basis on early effect and diagnosis of Pb poisoning.Materials and Methods:The exposure group consisted of 15 occupational Pb exposed workers from Hechi smeltery and Wuzhou storage battery factory. Among of them,there are 13 male and 2 female with the totally average age is 35.47±7.94(y)The control group consisted of 19 healthy volunteers who never exposed to Pb fume and other intoxicant.Among of them,there are 15 male and 4 female with the totally average age is 36.74±9.54(y).All subjects were asked to fill in the questionnaire through one by one.Investigation items were revised according to the "occupational health examination form" and included general state,occupational history,clinical symptom,past history, family history,health habit around workspace and so on.The concentration of Pb were measured by graphite furnace atomic absorption spectrometry.All subjects were scanned with PHILIPHS achieva 3.0T superconducting magnetic resonance formatter used for brain MRI and MRS.following imaging sequences:transverse fast spin-echo T2-weighted,transverse T1flair T1-weighted,coronal or sagittal T1flair T1-weighted imaging.1H-MRS was detected by single voxel spectroscopy using stimulated echo acquisition mode (STEAM)sequences.All spectra datum were postprocessed by the Functool software.The height of resonance peaks of different metabolites was measured and the rations of other metabolites to Cr were calculated.The experimental results were analysised by SPSS 13.0 statistical software package,and ANOVA analysis,t test,correlation analysis,regression analysisi and chi square test were used.Results:Occupational Pb exposure workers have obviously symptom,such as fatigued and weak,ache all over the body and limbs anesthesia and so on.The average level of blood Pb is 634.56±208.86 ug/L in exposure group,which is obviously higher than the level of blood Pb in control group(87.43±19.10 ug/L).It was found that hippocampal NAA/Cr was 1.222±0.082 in exposure group,which was obviously lower than 1.314±0.131 in control group (p＜0.05).Lip/Cr was 0.369±0.101 in exposure group,which was obviously higher than 0.264±0.094 in control group(p＜0.01).There was no significant difference in hippocampal Cho/Cr,MI/Cr and Glx/Cr between two groups. There was no signal difference after MRI examination.Hippocampal volume of left and right was 2.911±0.038cm~3 and 2.793±0.137 cm~3 in exposure group, which was respectively obviously lower than 3.093±0.079 cm~3和2.935±0.087 cm~3 in control group,but both didn't show atrophia.There was inverse correlation between NAA/Cr and the level of blood Pb(p=0.006, r=-0.464).There was positive correlation between Lip/Cr and the level of blood Pb(p=0.002,r=0.476).There was inverse correlation between hippocampal volume of left and right and the level of blood Pb(L:p=0.000,r=-0.574;R: p=0.008,r=-0.450)Conclusions:There was no signal intensity change in brain MRI following Pb exposure,but hippocampal volume of left and right were obviously smaller than the control with the same age,and gradually reduced with the increasing level of blood Pb.The metabolism in hippocamp had been changed after Pb exposure,possibly because the results of neuron loss or lesion,and cell membrane diffluent caused by Pb exposure.Maybe MRS is a kind of sensitive index to detect abnormalities of brain. |
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