Grid-Based Software for Quantification of Diabetic Retinal Nonperfusion on Ultra-Widefield Fluorescein Angiography

Area of Science:

• Ophthalmology
• Medical Imaging
• Diabetic Retinopathy Research

Background:

• Fluorescein angiography (FA) is crucial for diagnosing and managing retinal vascular diseases like diabetic retinopathy (DR).
• Ultra-widefield (UWF) FA enhances diagnostic potential by visualizing peripheral retinal changes.
• Quantifying retinal hypoperfusion, a key risk factor for proliferative DR, remains challenging.

Purpose of the Study:

• To evaluate the Michigan grid method, a software-based system, for detecting retinal hypoperfusion.
• To compare the Michigan grid method's efficacy against the traditional freehand method.
• To assess inter-rater reliability in hypoperfusion quantification using UWF-FA.

Main Methods:

• Acquisition of UWF fluorescein angiograms from 50 patients (10 healthy, 40 with non-proliferative DR).
• Quantification of retinal hypoperfusion by two masked graders using both freehand and Michigan grid methods.
• Statistical analysis of agreement using Cohen's weighted kappa.

Main Results:

• The Michigan grid method demonstrated substantial inter-rater agreement (kappa 0.711 for entire retina).
• Inter-rater reliability was comparable or slightly improved compared to the freehand method.
• Variations in segment classification (ungradable, perfused, nonperfused) were observed between graders.

Conclusions:

• The Michigan grid method offers a viable approach for evaluating FA-based hypoperfusion.
• Consistent and objective assessment of retinal nonperfusion requires further refinement.
• Integration of automated approaches may enhance future hypoperfusion quantification.