Gray and white matter volumetric and diffusion tensor imaging (DTI) analyses in the early stage of first-episode schizophrenia

Abstract 

Purpose

To determine whether statistical analyses of quantitative MR imaging data, including morphological changes, mean diffusivity (MD), and fractional anisotropy (FA), could provide useful biomarkers in early stage of first-episode schizophrenia.

Materials and methods

Twenty-three patients, who met all the criteria in the DSM-IV-TR category for schizophrenia excluding the duration of the disease (less than 6months of follow-up), were examined by MR imaging during the initial consultation. Nineteen of the 23 patients were finally diagnosed to have schizophrenia after a 6-month follow-up, and they were included in this study as having been in the early stage of first-episode schizophrenia. Nineteen healthy volunteers also underwent MR imaging as age-matched controls. Three-dimensional spoiled gradient recalled acquisition with steady state (3D-SPGR) and diffusion tensor imaging (DTI) were performed at 3T. Image processing for voxel-based morphometry, a fully automatic technique for a computational analysis of differences in regional brain volume throughout the entire brain, was conducted using the Statistical Parametric Mapping 5 software package (SPM5). The 3D-SPGR images in the native space were bias-corrected; spatially normalized; segmented into gray matter, white matter, and cerebrospinal fluid images; and intensity-modulated using SPM5. A voxel-based analysis was conducted using both the MD and FA maps computed from DTI. The customized MD and FA template specific to this study was created from all participants. Thereafter, all the MD and FA maps in the native space were transformed onto the stereotactic space by registering each of the images to the customized MD and FA template. The two groups were compared using SPM5. Age and sex were treated as confounding covariates.

Results

The patients demonstrated a significant increase in the MD of the left parahippocampal gyrus, left insula, and right anterior cingulate gyrus in comparison to the control subjects (FDR corrected p<0.05). No significant difference was observed in the correlation between the gray/white matter volume and FA.

Conclusion

These findings suggest that structural abnormalities in the brain are present during the early stage of first-episode schizophrenia and MD might therefore be a sensitive marker for the detection of these abnormalities.

Abbreviations: ADC, apparent diffusion coefficient, FA, fractional anisotropy, MD, mean diffusivity, VBM, voxel-based morphometry, DTI, diffusion tensor imaging, 3D-SPGR, The three-dimensional spoiled gradient recalled acquisition with steady state, SPM5, Statistical Parametric Mapping 5, CSF, cerebrospinal fluid

Keywords: 3T MR imaging, Apparent diffusion coefficient, Fractional anisotropy, Mean diffusivity, Voxel-based morphometry