Magnetic Resonance Imaging with Diffusion Tractography in Assessment of Cerebral Lesions Affecting the Optic Radiations

Background: The combination of Functional magnetic resonance imaging with Diffusion Tensor Imaging has proven scientific and clinical relevance. By measuring the directed provides complementary information on white matter architecture, i.e., on the course and integrity of functionally important white matter tracts. In the diffusion of protons along myelinated fibers, Diffusion Tensor neuroimaging research is mainly applied to study the human brain's structural connectivity, whereas diffusion tensor tractography is often also employed for clinical applications. Diffusion Tensor Imaging measurements can be obtained together with Functional magnetic resonance imaging in the same scanning session, which gives an even more complete picture of each patient's brain. This study aimed to assess cerebral lesions affecting optic radiations by magnetic resonance imaging with diffusion tensor imaging tractography.

Methods: Our prospective study was conducted on 30 cases ages ranged from 17-83 years, 10 of them were normal and considered as the control group and 20 patients were presented with clinical neurological symptoms and signs associated with visual abnormalities.

Results: There is a significant difference between the Fractional anisotropy difference and difference ratio between the two groups with a p-value of 0.016 and 0.017 respectively. There was a strong significant positive correlation between Fractional anisotropy difference ratio (%) and tractography; r = 0.716 (95% confidence interval: 0.470 - 0.858) and p-value <0.001. We correlated the pathological types with different patterns of tractography. optic radiations fiber tracts were displaced in 83.3% of benign tumors and infiltrated in 16.3%. while in malignant tumors optic radiations fiber tracts were displaced in 75%, infiltrated in 12.5%, and disrupted in 25%. There is no "gold standard" for in vivo tractography. Diffusion Tensor Imaging is the only method that permits the calculation and visualization of fiber tracts trajectories in vivo.

Conclusions: Diffusion Tensor Imaging tractography is clinically feasible and provides useful information regarding the site of optic radiations and their affection by different brain lesions also, surgical strategy for lesions located in eloquent visual areas. Also, there was a strong significant positive correlation between Fractional anisotropy difference ratio (%) and tractography distribution. Also, probabilistic multifiber tractography applied to diffusion Magnetic resonance imaging data acquired at 3T may be better as it can cope with crossing and kissing fibers than deterministic models because it allows many more possible local pathway orientations for each Diffusion Tensor Imaging sample point.