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

Abstract

Purpose: To demonstrate MR T₁ 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 T₁ 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 T₁ .

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 T₁ in the diseased eye compared to the healthy control eye (4.306 vs. 4.518 s, p = 0.008). T₁ times did not significantly alter across the range of vitronectin concentrations.

Conclusions: Ischemic eye disease decreases vitreous T₁ , potentially implying an increase in vitreous partial pressure of oxygen (pO₂ ) concentration given what is known from the relationship between 1/T₁ and pO₂ . Potential theories for this unexpected result are discussed. This study provides further data on this technique, with potential clinical application in eye disease.

Keywords: magnetic resonance imaging; oxygen; partial pressure; retinal vein occlusion; vitreous.