Diffusion tensor imaging of the optic radiations after optic neuritis.

Area of Science:

• Neuroimaging
• Neuroscience
• Ophthalmology

Background:

• Neurodegeneration in multiple sclerosis (MS) can be worsened by trans-synaptic degeneration.
• Identifying anterograde trans-synaptic degeneration in the visual pathway in vivo is crucial for understanding MS progression.

Purpose of the Study:

• To assess the presence of anterograde trans-synaptic degeneration in the primary visual pathway using diffusion tensor imaging (DTI).
• To correlate DTI findings with multifocal visual evoked potential (mfVEP) measurements in patients with a history of optic neuritis.

Main Methods:

• Diffusion tensor imaging (DTI) was used to analyze the optic radiations in 15 MS patients and 9 healthy controls.
• A probabilistic atlas of optic radiations was created from healthy diffusion tractography data.
• DTI parameters (λ(||), λ(⟂), MD, FA, α) and mfVEP latency/amplitude were analyzed and correlated.

Main Results:

• Patients showed decreased λ(||) in optic radiations, correlating with reduced mfVEP amplitude.
• Abnormal λ(⟂) and FA were found bilaterally but did not correlate with mfVEP changes.
• Abnormal α in the left optic radiations correlated with mfVEP amplitude loss.

Conclusions:

• Bilateral DTI abnormalities in optic radiations, coupled with reduced electrical activity, suggest anterograde trans-synaptic degeneration post-optic neuritis in MS.
• DTI parameters, particularly λ(||) and α, may serve as biomarkers for detecting trans-synaptic degeneration in the visual pathway.