The White Matter Microstructure Characteristics Of First Episode Depression Patients Based On DTI

ObjectiveBy using diffusion tensor imaging(DTI)and region of interest(ROI)in first episode depression(FED)patients,this study aimed to investigate the region interest brain microstructure characteristics in white matter of the patients who suffered from a first episode depression and without any treatment.And also observed the relationship between levels of score of 17-items of Hamilton Depression Scale and the disease duration with the parameters of DTI respectively.The different imaging features included fractional anisotropy(FA),mean dififusivity(MD),radial diffusivity(RD)and axial diffusivity(AD),and in all of the brain regions are measured to compare with two groups.The meaning of this research is to explore the specific biological makers and to provide new evidences for the new view of understanding the mechanism and early diagnosis of depressive disorder.Methods89 subjects from outpatient and inpatient who matched for age and gender and education were recruited,with 51 first episode depression patients and 38 normal healthy ones.All of them are right handed and had completed the 17-items of Hamilton Depression Scale.In addition,the duration time and the severity of the first episode of depression were collected.All the MRI data were acquired by a 3.OT magnetic resonance imaging scanner(GE Singa HDxt 3.OT)with eight-channel phase display coil to receive magnetic resonance signals.The routine MRI brain protocol including axial T1-weighted images(TR/TE=600ms/15ms),T2-weighted images(TR/TE=5200ms/140ms),and FLAIR(TR/TE=9000ms/120ms)for every subject to detect intracranial lesions.DTI scans were performed employing a single-shot echo-planar imaging(SS-EPI)sequence and arrayed spatial sensitivity encoding technique with the following parameters:33 non-collinear difiusion gradient directions with a b-value of 1000 sec/mm~2,flip angle(FA)= 90°,NEX=1,TR/TE=14000ms/minimum,field of view(FOV)=30*30cm,matrix size=128*128,slice thickness=2.4mm,no slice gap.In order to compare the different imaging features in DTI,the brain white matter fibers were divided into 50 ROIs and calculated based on the ROI algorithm.Used the t-test to compare the difference between diffusion tensor parameters in the first-episode depression group and the normal control group,p<0.05 was significantly different.To observe the relationship by using the multiple linear regression analysis between the FA value,MD value,AD value and RD value with the score of HAMD-17 and duration time.Finally made the correlation curve to express the relationship,p<0.05 was significantly different,ResultsThe MD values of right and left cortico spinal tract had significantly increased.Moreover the AD values of right cortico spinal tract and sagittal stratum also had significantly increased.In addition,RD value were significantly increased in both two sides cortico spinal tract.There were significant negative correlations between the MD value and the RD value of the left cortico spinal tract and the AD value of the right cortico spinal tract and the HAMD score.There was no significant difference of the FA value of the bilateral anterior or posterior limb of internal capsule,the cingulate gyrus and the hippocampus of the patients.The MD value of the right cortico spinal tract was related to the HAMD score,and the correlation curve showed the trend that the higher HAMD score level,the lower MD value in depression.There was no correlation between disease duration time and the DTI data.ConclusionWith the ROI analysis,depression of the brain in patients with extensive white matter microstructure changes,including the bilateral cortico spinal tract,right inferior longitidinal asciculus and inferior fronto-occipital fasciculus.It may lead to extensive transmission of information between the cortex and the white matter,which suggests that the frontal and marginal systems and other cognitive and emotional regulation may have a closely relationship with the neural loop.There were significant negative correlations between the DTI data of bilateral cortico spinal tract and the severity of the disease in the first episode of depression,which suggested that there was significant white matter damage in the early stage of depression.This study focused on observing the damage of brain fiber bundles based on ROI algorithm,which is more clearly about the changes in brain connectivity pathway.It suggested that white matter microstructure abnormalities may as a potential biomarker to explore the pathogenesis and the early diagnosis of depression possible.