Margareth Cristina Goncalves Kimura MD, Presenter: Nothing to Disclose

Rachael Deardorff MS, Abstract Co-Author: Nothing to Disclose

Ali Tabesh PhD, Abstract Co-Author: Nothing to Disclose

Maria De Fatima Falangola MD, PhD, Abstract Co-Author: Nothing to Disclose

M. Gisele Matheus MD, Abstract Co-Author: Nothing to Disclose

Leonardo Bonilha MD, PhD, Abstract Co-Author: Nothing to Disclose

Joseph A Helpern PhD, Abstract Co-Author: Nothing to Disclose

To examine white matter tract abnormalities related to schizophrenia using a new diffusion MRI technique, called Diffusional Kurtosis Imaging (DKI), which allows for the assessment of non-Gaussian diffusion thereby providing a more detailed analysis of cerebral cyto-architecture.  

T1-weighted magnetization-prepared rapid gradient echo (MPRAGE) and DKI images were obtained for schizophrenia patients (n = 11; age = 50.8 ± 11.1) and age/gender matched normal controls (n = 8; age = 49.3 ± 13.7) with a 3-Tesla MRI system. DKI data were acquired using an echo planar imaging (EPI) diffusion sequence with six b values (b=0, 500, 1000, 1500, 2000, 2500 s/mm2) and 30 diffusion encoding directions. DKI is an extension of diffusion weighted imaging (DWI) that allows one to obtain both diffusion and kurtosis tensors. In this study we calculate the fractional anisotropy (FA) and mean diffusivity (MD) using both DTI and DKI approaches as well as the mean kurtosis (MK) for comparison. All parametric maps were registered to a template and normalized. Images were smoothed and submitted to voxel-wise analysis with a two sided t-test and with an individual voxel threshold of p = 0.001 and cluster extent threshold of 100 voxels. All image processing and statistical analysis was performed on SPM-8. 

Several brain areas in schizophrenic patients showed decreased MK, FA DTI and FA DKI. FA DKI demonstrated five clusters, which may translate disorganization/dysfunction of connectivity, in the left superior temporal gyrus, basal ganglia and occipital area (Uncinate and Fronto-Occipital tracts topography) and surprisingly right pre-frontal area. There were no significant regions identified by MD. FADKI detected more areas of significantly altered white matter than FADTI using threshold of p=0.001.

This preliminary data demonstrates that DKI (FADKI) is able to identify more areas of significantly altered white matter and may be a more sensitive technique to detect possible cyto-architecture changes than (FADTI). This is expected since a DKI data set sample is acquired with more directions and broad as well as higher ranges of b-values.

Water diffusivity in complex environments such as brain is non-Gaussian. Therefore, methods that account for this behavior like DKI provide a better understanding of neuronal cyto-architecture.

Kimura, M, Deardorff, R, Tabesh, A, Falangola, M, Matheus, M, Bonilha, L, Helpern, J, Evidence of Altered White Matter Microstructure in Schizophrenia Using Diffusional Kurtosis Imaging.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11006226.html