Interactive retinal blood flow estimation from fluorescein angiograms

Abstract

It is well-known that age-related macular degeneration is the main cause of visual impairment in industrialised countries affecting around 239,000 people in UK while demonstrating an increasing trend. Fluorescein angiography is the most widely used technique in the diagnosis, prognosis and in following up the development of the disease. The interpretation of fluorescein angiograms depends upon the detection of abnormal fluorescence and clinical assessment of the functional integrity of retinal circulation, which is primarily based on subjective evaluation of the dye transit-time. This study presents a prototype system for quantitative analysis of the retinal haemodynamics. It analyses retinal blood flow based on the estimation of parameters such as mean transit-time, arteriovenous passage time and mean dye velocity. These parameters are estimated using densitometry and analysis of the vascular response. The prototype system consists of three main stages: vessel segmentation, image registration and blood flow estimation. The performance of the system is demonstrated on a comprehensive dataset, which contains images of normal retinas and retinas with pathologies such as wet age-related macular degeneration and branch retinal vein occlusion. The presented framework aims to demonstrate the technical feasibility for automated extraction of retinal blood flow parameters and contributes towards the development of a clinically proven computer vision system for quantitative analysis of fluorescein angiograms to assist NHS clinicians in the early diagnosis of age-related macular degeneration.