Abstract

Tractography refers to the process of tracing out the nerve fiber bundles from diffusion Magnetic Resonance Im-ages (dMRI) data acquired either in vivo or ex-vivo. Trac-tography is a mature research topic within the field of diffu-sion MRI analysis, nevertheless, several new methods are being proposed on a regular basis thereby justifying the need, as the problem is not fully solved. Tractography is usually applied to the model (used to represent the diffusion MR signal or a derived quantity) reconstructed from the acquired data. Separating shape and orientation of these models was previously shown to approximately preserve dif-fusion anisotropy (a useful bio-marker) in the ubiquitous problem of interpolation. However, no further intrinsic ge-ometric properties of this framework were exploited to date in literature. In this paper, we propose a new intrinsic recur-sive filter on the product manifold of shape and orientation. The recursive filter, dubbed IUKFPro, is a generalization of the unscented Kalman filter (UKF) to this product mani-fold. The salient contributions of this work are: (1) A new intrinsic UKF for the product manifold of shape and orien-tation. (2) Derivation of the Riemannian geometry of the product manifold. (3) IUKFPro is tested on synthetic and real data sets from various tractography challenge com-petitions. From the experimental results, it is evident that IUKFPro performs better than several competing schemes in literature with regards to some of the error measures used in the competitions and is competitive with respect to oth-ers.