title: Measurement tensors in diffusion MRI: generalizing the concept of diffusion encoding.
abstract: In traditional diffusion MRI, short pulsed field gradients (PFG) are used for the diffusion encoding. The standard Stejskal-Tanner sequence uses one single pair of such gradients, known as single-PFG (sPFG). In this work we describe how trajectories in q-space can be used for diffusion encoding. We discuss how such encoding enables the extension of the well-known scalar b-value to a tensor-valued entity we call the diffusion measurement tensor. The new measurements contain information about higher order diffusion propagator covariances not present in sPFG. As an example analysis, we use this new information to estimate a Gaussian distribution over diffusion tensors in each voxel, described by its mean (a diffusion tensor) and its covariance (a 4th order tensor).
authors.forename: Carl-Fredrik
authors.initials: CF
authors.lastname: Westin
authors.forename: Filip
authors.initials: F
authors.lastname: Szczepankiewicz
authors.forename: Ofer
authors.initials: O
authors.lastname: Pasternak
authors.forename: Evren
authors.initials: E
authors.lastname: Ozarslan
authors.forename: Daniel
authors.initials: D
authors.lastname: Topgaard
authors.forename: Hans
authors.initials: H
authors.lastname: Knutsson
authors.forename: Markus
authors.initials: M
authors.lastname: Nilsson
mesh_terms: D000465:Algorithms; D001921:Brain / Q000166:cytology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity