Quantitative MRI evaluation of glaucomatous changes in the visual pathway

Area of Science:

• Neuroimaging
• Ophthalmology
• Radiology

Background:

• Open-angle glaucoma (OAG) is a leading cause of irreversible blindness.
• Glaucomatous damage extends beyond the optic nerve and retina to affect the brain's visual pathways.
• Quantitative MRI techniques like VBM are crucial for detecting subtle brain changes.

Purpose of the Study:

• To quantitatively assess glaucomatous morphological changes in the visual cortex using VBM.
• To investigate the relationship between optic nerve damage and regional visual cortex atrophy in OAG patients.
• To explore the potential of MRI-based visual cortex evaluation for objective glaucoma assessment.

Main Methods:

• 31 OAG patients and 20 controls underwent T1-weighted 3D MPRAGE MRI for visual cortex gray matter density (GMD) analysis.
• Optic nerve cross-sectional area (CSA) was measured using T2-weighted MRI.
• Voxel-based morphometry (VBM) with SPM8 was used to calculate normalized GMD in Brodmann areas (BA) 17, 18, and 19.
• Spearman's rank correlation analyzed the relationship between optic nerve CSA and visual cortex GMD.

Main Results:

• Significant differences in optic nerve CSA and visual cortex GMD were found in OAG patients compared to controls across BA 17, 18, and 19.
• A significant positive correlation was observed between optic nerve CSA and GMD in BA 19 (r = 0.33, p = 0.023).
• No significant correlation was found between optic nerve CSA and GMD in BA 17 or BA 18.

Conclusions:

• Quantitative MRI evaluation of GMD can detect glaucoma-associated visual cortex atrophy.
• GMD in BA 19 is significantly correlated with optic nerve and retinal damage in OAG.
• Visual cortex MRI shows promise as an objective method for assessing glaucoma severity and brain involvement.