Quantification of voxel-wise total fibre density: Investigating the problems associated with track-count mapping

New Clinically Feasible 3T MRI Protocol to Discriminate Internal Brain Stem Anatomy

“…Currently there is debate on the validity of quantification due to tractography biases and errors and which method should be used. Average pathlength mapping (APM) was first introduced [37] and has now been followed by the more direct Apparent Fiber Density (AFD) [38]. The source DWI resolution (3mm isotropic) is relatively coarse and could potentially cause quantification errors in our maps.…”

Periventricular Nodular Heterotopia: Detection of Abnormal Microanatomic Fiber Structures with Whole-Brain Diffusion MR Imaging Tractography

“…This is relevant to the present work in that Track Density Imaging (TDI) does not provide a quantitative measure of white matter fibres (19,42). A number of recent novel methods in the technical literature can in principle facilitate quantitation of tractography streamlines (43)(44)(45)(46)(47); however, optimal use of such methods requires additional processing (48) to correct for track termination errors, and such processing requires reference data (to correct for image distortions) that are not available in this cohort of patients.…”

Super-Resolution Track Density Imaging: Anatomic Detail versus Quantification

“…14 Given these limitations, it could be argued that the power of super-resolution TDI is not as a quantitative tool but rather in the high anatomic contrast and detail it provides (as illustrated by the results from Hoch et al, 1 and other related studies 3,4,15,16 ). Quantification is therefore better performed on the basis of, for example, other complementary track-based parameters, such as track-weighted apparent diffusion coefficient (TW-ADC), trackweighted fractional anisotropy (TW-FA), and track-weighted fiber-orientation distribution (TW-FOD), 12,17 or even on the basis of other properties of the streamlines themselves (such as their lengths in the average pathlength map [APM] method) 13 or on measures of the voxelwise fiber-orientation distribution (such as those related to the apparent fiber density [AFD] method).…”

“…Quantification is therefore better performed on the basis of, for example, other complementary track-based parameters, such as track-weighted apparent diffusion coefficient (TW-ADC), trackweighted fractional anisotropy (TW-FA), and track-weighted fiber-orientation distribution (TW-FOD), 12,17 or even on the basis of other properties of the streamlines themselves (such as their lengths in the average pathlength map [APM] method) 13 or on measures of the voxelwise fiber-orientation distribution (such as those related to the apparent fiber density [AFD] method). 14,18 While these maps have reduced anatomic contrast relative to that seen in TDI maps, they have more reliable quantitative properties 12,13 and are therefore more suitable for quantitative analysis in clinical applications.…”