A Study Of Mild-to-Moderate Traumatic Brain Injury With Multivoxel Proton Magnetic Resonance Spectroscopy In Adult Patients

ObjectiveTo investigate the significance of multivoxel proton magnetic resonance spectroscopy(1H-MRS) in evaluating mild-to-moderate traumatic brain injury(TBI) in adult patients .N-aceytl aspartate(NAA), choline (Cho), creatine (Cr), lactate(Lac)and some other metabolites from frontal and temporal lobe areas were detected to noninvasively analyse the pathologic physiology of post-traumatic brain tissue in vivo, and to identify the location and severity of"extremely mild traumatic brain injury", which had normal CT or MRI manifestation.MethodsConventional MRI and multivoxel 1H-MRS examinations were performed in forty-eight adult patients of mild-to-moderate TBI and sixteen matched healthy volunteers. Metabolites of injured-side frontal and temporal lobe areas were collected by 1H-MRS,and NAA,Cr,Cho were acquired with half-quantitative analysis. The examination protocol was 2D chemical shift imaging free induction decay.The spectra were analyzed by measuring the areas under peaks of various metabolites. Glasgow outcome scale(GOS) was applied to do some of the cases for prognosis evaluation, then the correlation between ratios of NAA,NAA/Cr,NAA/Cho and the scores of GOS was observed. For eight cases without radiological image changes in early stage, the colour-coded imaging which represented signal intensity of metabolites(NAA/Cr,Cho/Cr,NAA/Cho) was fused with axial T2WI imaging to measure the distribution of these metabolites in frontal and temporal lobe areas bilaterally.ResultsIn mild TBI group, the ratio of NAA/Cr,Cho/Cr in the injured-side was significantly lower than normal-appearing contralateral cortex(P<0.01);In moderate TBI group, the ratio of NAA,NAA/Cr,Cho/Cr and NAA/Cho in the injured-side was significantly lower than normal-appearing contralateral cortex(P<0.01);Compared with moderate group, the NAA,NAA/Cr and NAA/Cho ratios in mild group increased obviously(P<0.01); There were statistically significant differences about the NAA,Cr levels between injuered region and surrounding region in mild group (P<0.05) and about the Cho,Cr levels in moderate group(P<0.05);the NAA,NAA/Cr,NAA/Cho and Cho/Cr levels in TBI group decreased significantly compared with normal control group.In mild group, both NAA and NAA/Cr levels were obviously lower than that in extremely mild group; In extremely mild group, the Cho/Cr levels of forejudged injured-side was significantly lower than that in the contralateral cortex(P<0.05).Through the fusion of the colour-coded imaging and the routine MRI imaging, the difference of the signal intensity of the ratio of NAA/Cr,Cho/Cr and NAA/Cho in forejudged injured-side would be straightly detected.There was significant positive correlation between the ratio of NAA,NAA/Cr and NAA/Cho in the injured-side of TBI group and the scores of glasgow coma scale(GCS) and GOS(P<0.01) .ConclusionsMultivoxel proton magnetic resonance spectroscopy could be applied to early diagnose, evaluate and prognose in mild-to-moderate TBI adult patients, especially for extremely mild TBI. 1H-MRS was superior to conventional MRI in detecting early abnormality of the brain tissue. The NAA,NAA/Cr and NAA/Cho ratios in injured-side could reflect the severity of brain injury objectively. Reversible decrement of NAA,NAA/Cr and Cho/Cr in post-traumatic brain tissue indicated that the damage could be partly repaired and reconstructed at some extent, and such reversible decrement could be indicative of the recoverability of neuronal function, which was of practical value in distinguishing fatal from sub-fatal neuronal injuries.