title: Non-uniform gradient prescription for precise angular measurements using DTI.
abstract: Diffusion Tensor Imaging (DTI) calculates a tensor for each voxel, representing the mean diffusive characteristics in volume-averaged tissue. Gradients that phase-encode spins according to the amount of their diffusion are usually applied uniformly over a sphere during a DTI procedure for minimal bias of tensor information. If prior knowledge of diffusion direction exists, the angular precision for determining the principle eigenvector of cylindrically-symmetric ("prolate") tensors can be improved by specifying gradients non-uniformly. Improvements in precision of 30-40% can be achieved using a restricted band of zenith angle values for gradient directions. Sensitivity to the a priori angular range of the principle eigenvector can be adjusted with the width of the band. Simulations and phantom data are in agreement; a preliminary validation is presented.
authors.affiliation: Department of Radiology, Medical College of Georgia, USA. nyanasak@mcg.edu
authors.forename: Nathan
authors.initials: N
authors.lastname: Yanasak
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Allison
authors.forename: Qun
authors.initials: Q
authors.lastname: Zhao
authors.forename: Tom C C
authors.initials: TC
authors.lastname: Hu
authors.forename: Krishnan
authors.initials: K
authors.lastname: Dhandapani
mesh_terms: D000465:Algorithms; D001185:Artificial Intelligence; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity