  Background: Diffusion tensor imaging (DTI) has been used to characterize
forearm muscle architecture. Since only uniform sampling is performed for seed
points rather than fiber tracts, the tracts may be unevenly distributed in the
muscle volume. Purpose: To reconstruct uniformly distributed fiber tracts in
human forearm by filtering the tracts from DTI. Assessment: Farthest streamline
sampling (FSS) was proposed for filtering and compared with two conventional
methods, i.e., two-dimensional sampling and three-dimensional sampling. The
uniform coverage performance of the methods was evaluated by streamline
coverage (SC) and the coefficient of variation of streamline density (SDCV).
Architectural parameters were calculated for 17 forearm muscles. Anatomical
correctness was verified by 1. visually assessing the fiber orientation, 2.
checking whether the architectural parameters were within physiological ranges,
and 3. classifying the architectural types. Results: FSS had the highest SC
(0.93+0.04) and the lowest SDCV (0.34+0.06) among the three methods (P<0.05).
FSS reduced the sampling of long tracts (10% reduction in fiber length,
P<0.05), and the architectural parameters were within physiological ranges (two
parameters with P<0.05). The fiber orientation of the tractography was visually
consistent with that of the cadaveric specimen. The architectural types of 16
muscles were correctly classified, except for the palmaris longus, which had a
linear arrangement of fiber endpoints (R2=0.95+0.02, P<0.001). Data Conclusion:
FSS reconstructed more muscle regions and uniformly distributed fiber tracts.
The tracts were anatomically correct, indicating the validity of fiber tracts.
Key Words: diffusion tensor imaging; forearm muscles; architectural properties
