Abstract
Purpose: :
To measure retinal vascular leakage in mice eyes with MRI imaging
Methods: :
Retinal vascular leakage was induced in mice eyes by generating choroidal Neovascularization (CNV) by laser-injury. Briefly, a 532nM argon laser was used to rupture Bruch’s membrane. Each mouse had 10 shots applied to one eye; the fellow non-lasered eye served as a control.MRI was conducted in a 4.7T Bruker PharmaScan (Bruker BioSpin, Ettlingen, Germany) using a T1 weighted spin-echo sequence. Images were acquired continuously for 30min during the administration of 1.0uL/g Gd-DTPA as contrast agent, at one image per 6 minutes with a resolution of 0.133x0.133x0.7 mm3. To quantify vascular leakage, a small region of interest is drawn in the vitreous. The signal intensity averaged from 6 to 24 min post-injection was calculated as a percentage of the pre-contrast intensity to determine the percent enhancement.Vascular leakage was compared between eyes on Day 5, 7, 19 & 26. In a second study, mice were lasered and were dosed with vehicle or a VEGF inhibitor. Vascular leakage was compared between treatment groups, and between the two eyes.
Results: :
With the laser-induced lesion, prominent enhancement could be observed in the eye post injection of the contrast agent (observed on day 5 through 26). The enhancement can be tracked noninvasively and longitudinally. Moreover, treatment with a VEGF inhibitor is able to significantly reduce the enhancement.
Conclusions: :
Using a laser-injury-induced mouse model of CNV, the present study shows that the resultant vascular leakage can be visualized and quantified by dynamic-contrast-enhanced MRI. Moreover, the technique can be used to assess treatment effect in this model, as demonstrated with administration of a VEGF inhibitor.
Keywords: choroid: neovascularization • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)