Scoping literature review: Comparing MRI tractography methods for optic radiation analysis

Accurate tractography mapping of the optic radiations is essential to avoiding post-operative visual field deficits in patients undergoing temporal lobe surgery. This literature review highlights the current landscape of MRI tractography methods that are used to delineate the optic radiations (ORs), with a particular focus on the anterior segment known as Meyer's loop. By synthesizing findings from the past decade of research on probabilistic and deterministic tractography models, this literature review underscores the limitations of traditional DTI-based approaches and the need for methodologically tailored protocols that consider anatomical complexity and tract curvature. We performed a systematic review following PRISMA guidelines to compare DTI-based deterministic and probabilistic tractography methods. Twelve studies were included in this scoping literature review. Low-threshold probabilistic tractography (≤1%) emerged as the most anatomically accurate and reliable method for delineating the ORs because it placed the ML anterior border close to dissection-based ground truth and preserved the curved anterior trajectory that deterministic streamlining tends to truncate. However, this approach has a high computational cost which may make it difficult to use in clinical settings. Emerging deterministic techniques such as anatomically constrained tractography, MAGNETic tractography, and parallel transport tractography demonstrate a significant improvement in mapping the full anterior extent and volume of the ORs compared to current deterministic approaches. These methods offer promising, clinically applicable advancements in OR tractography studies.