This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The retina is metabolically very active. With limited energy reserve, the retina depends solely on a continuous and adequate supply of oxygen and nutrients to maintain its functional and structural integrity. If blood flow is compromised, irreversible retinal cell damage could occur within minutes, which could result in visual impairment or vision loss. Oxygenation and perfusion deficits have been implicated in numerous retinal diseases, including diabetic retinopathy, glaucoma and macular degeneration. A non-invasive method to measure retinal oxygenation and perfusion at tissue level would be valuable since changes in these parameters generally precede anatomical abnormalities and/or clinical symptoms. The long-term goal of this project is to establish a non-invasive method, using magnetic resonance imaging (MRI), to assist clinicians in the diagnosis and treatment of retinal diseases. The immediate objective of this proposal is to develop a non-invasive MRI methodology to dynamically map changes in retinal oxygenation and perfusion following visual stimuli. While functional MRI (fMRI) and perfusion imaging using the conventional gradient-echo, blood-oxygenation-level-dependent (BOLD) technique is routine for non-invasive mapping of brain functions, its application to the eye is technically more difficult because of the retina?s proximity to the air-filled cranial sinuses and nasal cavity. These large air-tissue interfaces could cause drastic signal loss and image distortion. In this application, we will develop and validate a BOLD fMRI technique to measure stimulus-evoked oxygenation changes, and a perfusion-based fMRI technique to measure stimulus-evoked perfusion changes at very high spatial resolution. These techniques will then be applied to evaluate changes in retinal oxygenation and perfusion following to visual stimuli. We propose to carry out these studies on a cat model using a 4.7 Tesla magnet.
Showing the most recent 10 out of 912 publications
