Inter- and Intra-Rater Reproducibility of Standardized Frontal Aslant Tract Reconstruction Using Deterministic Diffusion Tensor Tractography: Implications for Neurosurgical Planning

Background/Objectives: Diffusion tensor tractography is used to visualize white matter pathways relevant to neurosurgical planning, but manual ROI-based reconstruction may be operator-dependent. This study assessed the inter-rater and intra-rater reproducibility of a standardized deterministic protocol for reconstruction of the frontal aslant tract (FAT). Methods: Diffusion-weighted MRI datasets from 30 neurologically healthy adults were retrospectively reanalyzed. Three independent raters reconstructed the left and right FAT using the same standardized protocol, with identical predefined ROI locations and fixed tracking parameters; however, each rater independently delineated the ROIs. Reconstructions were repeated after 3 weeks. Spatial agreement was assessed using the Dice similarity coefficient and HD95, while reliability of fractional anisotropy (FA), mean diffusivity (MD), and tract volume were evaluated using intraclass correlation coefficients (ICC). Results: FAT reconstruction was successful in 339 of 360 attempts (94.2%), with a higher success rate for the left than for the right FAT (96.7% vs. 91.7%). Mean inter-rater Dice similarity was 0.74 for the left FAT and 0.69 for the right FAT. Inter-rater reliability was highest for FA (ICC 0.88–0.90), followed by MD (ICC 0.85–0.88) and tract volume (ICC 0.79–0.84). Intra-rater agreement was consistently higher than inter-rater agreement. Conclusions: Standardized deterministic FAT reconstruction demonstrated moderate-to-good reproducibility, although operator-dependent variability remained. These findings provide baseline estimates of procedural reliability and support further evaluation of standardized ROI-based tractography approaches.