Tractography of the optic radiation: a repeatability and reproducibility study

Area of Science:

• Neuroimaging
• Diffusion MRI
• Tractography

Background:

• The optic radiation (OR) is crucial for visual processing.
• Accurate reconstruction of the OR from diffusion MRI (dMRI) is essential for clinical applications, including surgical planning.
• Evaluating the reliability of OR reconstruction methods is necessary for their widespread adoption.

Purpose of the Study:

• To assess the repeatability and reproducibility of optic radiation (OR) reconstruction using diffusion MRI (dMRI) data.
• To compare different diffusion profile estimation methods (single tensor, Q-ball, persistent angular structure) for OR reconstruction.
• To evaluate the reliability of dMRI metrics and anatomical dimensions of the OR.

Main Methods:

• 14 adults underwent two dMRI scans using a 60-direction sequence.
• Optic radiation segmentation was performed using probabilistic tractography with standard and extended regions of interest (ROIs).
• Repeatability and reproducibility were quantified using intra-class correlation coefficients (ICCs) and Bland-Altman plots.

Main Results:

• Good to excellent ICCs were observed for both repeatability and reproducibility of dMRI metrics, Dice similarity coefficient (DSC), and ML-TP distance.
• Multi-fiber methods (QSH, PAS) and a standard set of ROIs yielded higher ICC values.
• Bland-Altman plots indicated no systematic bias in reproducibility measurements.

Conclusions:

• Multi-fiber OR reconstruction methods demonstrate good to excellent repeatability and reproducibility.
• The findings support the use of multi-fiber OR reconstruction with a limited set of ROIs in clinical practice.
• This approach is suitable for OR microstructure characterization and dimensional analysis in neurosurgical planning.