Asymmetric Orientation Distribution Functions (AODFs) revealing intravoxel geometry in diffusion MRI

作     者：Karayumak, Suheyla Cetin Ozarslan, Evren Unal, Gozde 

作者机构：Brigham & Womens Hosp Psychiat Neuroimaging Lab Boston MA 02115 USA Harvard Med Sch Boston MA USA Sabanci Univ Fac Engn & Nat Sci Istanbul Turkey Linkoping Univ Dept Biomed Engn Linkoping Sweden Linkoping Univ Ctr Med Image Sci & Visualizat Linkoping Sweden Istanbul Tech Univ Dept Comp Engn Istanbul Turkey 

出 版 物：《MAGNETIC RESONANCE IMAGING》 (磁共振成像)

年 卷 期：2018年第49卷

页      面：145-158页

核心收录：

学科分类：080805[工学-电工理论与新技术] 080904[工学-电磁场与微波技术] 0808[工学-电气工程] 0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 1009[医学-特种医学] 

基　　金：Linkoping University Center for Industrial Information Technology (CENIIT) 

主　　题：ODF regularization Asymmetric fiber orientations Fiber asymmetry measure Asymmetric ODF (AODF) Directional spatial filtering Steerable filtering Diffusion MRI HARDI 

摘      要：Characterization of anisotropy via diffusion MRI reveals fiber crossings in a substantial portion of voxels within the white-matter (WM) regions of the human brain. A considerable number of such voxels could exhibit asymmetric features such as bends and junctions. However, widely employed reconstruction methods yield symmetric Orientation Distribution Functions (ODFs) even when the underlying geometry is asymmetric. In this paper, we employ inter-voxel directional filtering approaches through a cone model to reveal more information regarding the cytoarchitectural organization within the voxel. The cone model facilitates a sharpening of the ODFs in some directions while suppressing peaks in other directions, thus yielding an Asymmetric ODF (AODF) field. We also show that a scalar measure of AODF asymmetry can be employed to obtain new contrast within the human brain. The feasibility of the technique is demonstrated on in vivo data obtained from the MGH-USC Human Connectome Project (HCP) and Parkinson s Progression Markers Initiative (PPMI) Project database. Characterizing asymmetry in neural tissue cytoarchitecture could be important for localizing and quantitatively assessing specific neuronal pathways.