Retinal diffusion restrictions in acute branch retinal arteriolar occlusion

Area of Science:

• Ophthalmology
• Radiology
• Neuroimaging

Background:

• Branch retinal arteriolar occlusion (BRAO) is a type of retinal vascular occlusion.
• Diffusion-weighted imaging (DWI) is a standard MRI technique for stroke detection.
• Retinal diffusion restrictions (RDR) have been observed in central retinal artery occlusion.

Purpose of the Study:

• To investigate the occurrence and detectability of RDR in BRAO using standard brain DWI.
• To assess the reliability of RDR detection in BRAO.
• To compare RDR detection rates based on MRI parameters.

Main Methods:

• Retrospective cohort study evaluating 89 DWI MRI scans from 85 BRAO patients.
• Two radiologists assessed scans for RDR.
• Inter- and intra-rater reliability calculated using Kappa statistics.
• Detection rates analyzed by MRI field strength, sequence type, and time from onset.

Main Results:

• Overall sensitivity for RDR in BRAO was 46.1%, with low ADC signal in 56.1%.
• RDR localization correlated with fundoscopic retinal edema in 85% of cases.
• Inter-rater agreement was substantial (κ=0.64), and intra-rater agreement was excellent (κ=0.87).
• Detection rates trended higher on 3T vs. 1.5T MRI (53.7% vs. 34.3%).
• RDR were identified up to two weeks after visual impairment onset.

Conclusions:

• Standard stroke DWI can detect RDR in a substantial proportion of BRAO cases.
• Sensitivity and inter-rater reliability for RDR in BRAO are lower than reported for central retinal artery occlusion.
• DWI is a valuable tool for diagnosing BRAO, particularly when combined with clinical findings.