Comparison of multiple tractography methods for reconstruction of the retinogeniculate visual pathway using diffusion MRI

Abstract

The retinogeniculate visual pathway (RGVP) conveys visual information from the retina to the lateral geniculate nucleus. The RGVP has four subdivisions, including two decussating and two nondecussating pathways that cannot be identified on conventional structural magnetic resonance imaging (MRI). Diffusion MRI tractography has the potential to trace these subdivisions and is increasingly used to study the RGVP. However, it is not yet known which fiber tracking strategy is most suitable for RGVP reconstruction. In this study, four tractography methods are compared, including constrained spherical deconvolution (CSD) based probabilistic (iFOD1) and deterministic (SD-Stream) methods, and multi-fiber (UKF-2T) and single-fiber (UKF-1T) unscented Kalman filter (UKF) methods. Experiments use diffusion MRI data from 57 subjects in the Human Connectome Project. The RGVP is identified using regions of interest created by two clinical experts. Quantitative anatomical measurements and expert anatomical judgment are used to assess the advantages and limitations of the four tractography methods. Overall, we conclude that UKF-2T and iFOD1 produce the best RGVP reconstruction results. The iFOD1 method can better quantitatively estimate the percentage of decussating fibers, while the UKF-2T method produces reconstructed RGVPs that are judged to better correspond to the known anatomy and have the highest spatial overlap across subjects.Overall, we find that it is challenging for current tractography methods to both accurately Jianzhong He and Fan Zhang are co-first-authors.

Multishell Diffusion MR Tractography Yields Morphological and Microstructural Information of the Anterior Optic Pathway: A Proof-of-Concept Study in Patients with Leber’s Hereditary Optic Neuropathy

“…Tractography is a method that converts volumetric maps of diffusion characteristics into estimates of the probable location white matter tracts, based on the generation of streamlines linking adjacent voxels. The MRtrix tool tckgen generated streamlines using a first-order integration over fibre orientation distributions (iFOD1) approach, following [ 25 ].…”

Visualization of human optic nerve and tract by diffusion tensor mapping and degree of neuropathy

“…Founded masks can be automatically corrected by σ parameter, which may be a threshold value used for semi-automatic segmentation [75], or active contour segmentation [76]. Both methods can be alternatives to different tractography segmentations [33] and manual methods.…”

“…It is challenging for current tractography methods to accurately track optic pathway bers that correspond to known anatomy and reproduce reasonably decussating bers. However, systematic progress is being reported [33] and several studies have shown successful tracking of some parts of the optic pathway [34][35][36][37][38]. Examples of visualization of retinogeniculate visual pathway ber displacement due to tumors have been reported in [36,37,39].…”

“…An abnormal signal near the optic canal (Fig. 1c), where the optic nerve is surrounded by bone and air, results in negative diffusion tensor eigenvalues [33]. The small size of the optic nerve and its movement during scanning make it even harder to obtain high-quality images.…”

Visualization of human optic nerve by diffusion tensor mapping and degree of neuropathy

“…It is challenging for current tractography methods to accurately track optic pathway fibers that correspond to known anatomy. However, systematic progress is being reported [ 34 ] and several studies have shown successful tracking of some parts of the optic pathway [ 35 – 39 ]. Examples of visualization of retinogeniculate visual pathway fiber displacement due to tumors have been reported in [ 37 , 38 , 40 ].…”