Toshiaki Taoka MD, Presenter: Nothing to Disclose

Toshiaki Akashi MD, Abstract Co-Author: Nothing to Disclose

Toshiteru Miyasaka MD, Abstract Co-Author: Nothing to Disclose

Hiroyuki Nakagawa MD, Abstract Co-Author: Nothing to Disclose

Aya Hashimoto MD, Abstract Co-Author: Nothing to Disclose

Kimihiko Kichikawa MD, Abstract Co-Author: Nothing to Disclose

Takeshi Wada MD, Abstract Co-Author: Nothing to Disclose

00030490-DMT et al, Abstract Co-Author: Nothing to Disclose

The purpose of this study is to evaluate feasibility of using diffusion tensor parameters in fibers of limbic circuit by tract-based diffusion tensor analysis as surrogate marker of Alzheimer disease (AD). We evaluated fractional anisotropy (FA) and apparent diffusion coefficient (ADC; sec/mm2) along tracts included in limbic circuit and analyzed correlation with MMSE score. We also made an analysis in voxel-based morphometry for the same population.

The subjects were 130 AD cases. Age matched 30 control subjects were also evaluated. Diffusion tensor images were obtained by single shot echo planar sequence and images for voxel based morphometry were obtained by MPRAGE sequence on 1.5T clinical scanner. We acquired tractographies of uncinate fasciculus, anterior cingulum and posterior cingulum using diffusion tensor analysis software. We measured FA and ADC along the three tracts and evaluated correlation with MMSE score. We acquired z-scores of anterior part of parahippocampal gyrus to normal controls and evaluated correlation between the z-scores and MMSE scores.

There are positive correlation between FA and MMSE score for the three tracts, and the correlation coefficient was 0.20 (p<0.05) for uncinate fascicles (square, solid line in the figure), 0.49 (p<0.001) for anterior cingulum (black circle, dotted line) and 0.46 (p<0.001) for posterior cingulum (white circle, broken line). There are negative correlation between ADC and MMSE score for three tracts and the correlation coefficient was -0.36 (p<0.001) for uncinate fascicles, -0.42 (p<0.001) for anterior cingulum and -0.47 (p<0.001) for posterior cingulum. While, there are slight negative correlation between z-score of voxel based morphometry and MMSE score, and the correlation coefficient was -0.18 (not significant).

Increased diffusivity and decreased diffusion anisotropy in limbic circuits correlated to the severity of AD and both of them has good correlation to MMSE score, compared to z-score of voxel based morphometry. Diffusivity and diffusion anisotropy in limbic circuits by tract specific analysis seems to be useful as a surrogate marker of severity of AD.

Diffusivity (ADC) and diffusion anisotropy (FA) in limbic circuits can be used clinical practice for diagnosis, follow-up and treatment assessment for Alzheimer disease.

Taoka, T, Akashi, T, Miyasaka, T, Nakagawa, H, Hashimoto, A, Kichikawa, K, Wada, T, et al, 0, Tract-specific Diffusion Tensor Analysis of Fibers in Limbic Circuits as a Surrogate Marker of Alzheimer Disease: Comparison with Voxel-based Morphometry.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8008483.html