In vivo measurement of T₁ in the vitreous humor of patients with ischemic retinal disease

Purpose: To demonstrate MR T-1 mapping in vivo as a method to non-invasively estimate vitreous oxygen concentration in ischemic eye disease.Methods: Patients with ischemic eye disease (central retinal vein occlusion, ocular ischemic syndrome, and proliferative diabetic retinopathy) were prospectively recruited. MRI was performed on each patient before any treatment, with T-1 mapping acquired using an inversion recovery TrueFISP sequence at several inversion times, from a single slice positioned through the center of both eyes in the axial oblique plane. A phantom study measuring seven different concentrations of vitronectin, a protein released in ischemic eye disease, was undertaken to determine its potential confounding effect on T-1.Results: Ten participants were recruited (eight central retinal vein occlusion, one ocular ischemic syndrome, and one proliferative diabetic retinopathy). Of the eight central retinal vein occlusion cases, there was a statistically different vitreous T-1 in the diseased eye compared to the healthy control eye (4.306 vs. 4.518 s, p = 0.008). T-1 times did not significantly alter across the range of vitronectin concentrations.Conclusions: Ischemic eye disease decreases vitreous T-1, potentially implying an increase in vitreous partial pressure of oxygen (pO(2)) concentration given what is known from the relationship between 1/T-1 and pO(2). Potential theories for this unexpected result are discussed. This study provides further data on this technique, with potential clinical application in eye disease.