Purpose:
Edema is an early indicator of retinal injury. The current opticalimaging methods are limited in detecting retina edema. Magneticresonance imaging (MRI) determined apparent water diffusioncoefficient (ADC) decreases in cytotoxic brain edema. The currentstudy will assess the effect of cytotoxic edema on retina ADCusing high-resolution diffusion weighted MRI (DWI) in vivo at11.74T.
Methods:
Cytotoxic edema of retina from adult C57/BL6 mice (n = 5) wereinduced by intraperitoneal infusion of de-ionized water equalto 15% of its body weight over a 15-min period. Diffusion weightedimages were acquired before (baseline) and 35 min after (treated)the infusion. The 35-min retina ADC was normalized to the baselinevalue. All images were acquired with 47 × 94 × 500 µm3voxel size. Statistical significance was accepted at p <0.05 using paired student t-test.
Results:
Three MRI-detected layers have been observed at baseline and35 min after infusion on both T2-weighted images (Figs 1A&B)and calculated ADC maps (Figs. 1C & D). A 19% decrease inADC has been observed in the treated retina (Fig. 2, p <0.05).
Conclusions:
The substantial decrease of ADC in the treated mouse retinais consistent with the ADC changes seen in the brain from miceof hyponatremia, reflecting the acute cytotoxic retina edema.The current finding suggests that DWI can be used to detectretina edema in mice non-invasively.
Keywords: edema • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina