Region-of-interest and tractographic methods, although they face other challenges, 7 at least have an a priori location within a specific tract or tracts.
The local measure, such as FA, reflects the white matter integrity or the consistency of fiber orientation at microstructural level, while the nodal properties of brain connectome, such as nodal efficiency, are an integrated metric of global information flow capacity and related to all of the nodal connections, which consist of a specific tract or several tracts together.
It can produce false negatives, for example, when DTI-derived metrics changes occur along a specific tract, but the exact location where the change is most pronounced along the tract differs across subjects or hemispheres.
In this context, it is essential to identify and to quantify the source of error, not only for a specific tract, but for a whole brain tractography experiment.
Mean fractional anisotropy values over a specific tract were computed only for subjects where tractography analyses were able to identify streamlines connecting specified seed and target regions.
The Johns Hopkins University International Consortium for Brain Mapping (JHU ICBM -DTI-81 whICBM -DTI-81tlas [ 35] and JHU whICBM -DTI-81ractography atlas [ 36] labels were used to label significant voxels and assign a specific tract name.
Proportional tract lesion load was determined for each individual tract as the volume overlap between the lesion mask in a certain individual, and the volume of a specific tract mask for that individual, expressed as a percentage of overall tract volume (Supplementary Fig. 2C and D).
Depending on the specific tract, or the anatomical plausibility of initial reconstructions, such ROIs can be combined; for example, a tract may pass through ROI-1 'AND' ROI-2 but 'NOT' ROI-3.
These findings could indicate that – beyond an undoubted diffuse neurodegenerative process in MS which is detectable by measurement of global brain tissue loss and also by RNFL measurements - additional progressive neurodegenerative damage may evolve in specific tracts or functional systems such as the visual pathway.
While aggregation sites like FindTheBest give home seekers an advantage that they didn't have when they had to rely exclusively on real estate agents for information -- many of whom are limited in expertise to a specific area, tract or home, Babb notes -- one of their biggest drawbacks is the room they leave for data to be misinterpreted.
Hence, the displacement or disruption of a specific fiber tract by a tumor may be assessed by 3D tractograms, providing useful information in terms of pre-surgical planning [ 31, 32].
