Photoreceptor degeneration changes magnetic resonance imaging features in a mouse model of retinitis pigmentosa

Retinal degeneration-1 (rd1) mice are animal models of retinitis pigmentosa, a blinding disease caused by photoreceptor cell degeneration. This study aims to determine magnetic resonance imaging (MRI) changes in retinas of 1- and 3-month-old rd1 mice. Apparent diffusion coefficient in retina was measured using diffusion MRI. The blood-retinal barrier leakage was evaluated using gadolinium-diethylenetriaminepentaacetic acid-enhanced T ₁-weighted MRI before and after systemic gadolinium- diethylenetriaminepentaacetic acid injection. Photoreceptor degeneration in rd1 retina was apparent by decreased retinal thickness and loss of water diffusion anisotropy in both 1- and 3-month-old rd1 mice. Furthermore, statistically significant increase of mean retinal apparent diffusion coefficient and gadolinium-diethylenetriaminepentaacetic acid-enhanced T₁-weighted MRI signals were observed in 3-month-old rd1 mice comparing with age-matched wild-type mice. Together, these data suggest that MRI parameter changes can signature common pathological changes in photoreceptor-degenerated eyes, particularly blood-retinal barrier leakage-induced retinal edema.