The retina is approximately 300 mu m thick and is metabolically very active. With limited energy reserve, it depends solely on a continuous supply of oxygen and nutrients to maintain its functional and structural integrity. The retina is nourished by two blood supplies, namely, the retinal and choroidal circulation, that feed the inner (i.e., ganglion cells) and the outer (i.e., photoreceptors) retina, respectively. Oxygen transport into the highly structured retinal cell layers relies heavily on diffusion. As such, the oxygen tension midway between the inner and outer retina is close to hypoxic level under normal conditions and, thus, the retina is very susceptible to ischemic injury. Oxygenation and perfusion deficits have been implicated in numerous retinal diseases. A non-invasive method to map changes in retinal and choroidal oxygenation and perfusion would be valuable. Non-invasive magnetic resonance imaging (MRI) has been widely used for investigating anatomy, physiology and function in both animals and humans. While tissue oxygenation and perfusion imaging is routine for studying brain functions, its application to the eye is technically difficult due to the thin retina and its proximity to the air-filled cranial cavity. Recent data from our lab demonstrate that blood-oxygenation-level-dependent (BOLD) functional MRI can dynamically map visual-evoked changes in oxygenation in the retina. The main goals of this proposal are: 1) to develop and validate high-resolution (58x58x1000 mu m3) MRI modalities to map choroidal and retinal oxygenation and perfusion in the retina, and 2) to investigate the visual-evoked layer-specific responses to differential activations of photoreceptor versus ganglion cell activity by measuring changes in the choroidal versus retinal oxygenation and perfusion. Studies will be performed on cats using a 4.7 Tesla scanner.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY014211-03
Application #
6838767
Study Section
Diagnostic Imaging Study Section (DMG)
Program Officer
Dudley, Peter A
Project Start
2004-01-01
Project End
2007-12-31
Budget Start
2005-01-01
Budget End
2005-12-31
Support Year
3
Fiscal Year
2005
Total Cost
$380,250
Indirect Cost
Name
Emory University
Department
Neurology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Bresnen, Andrew; Duong, Timothy Q (2015) Brain high-energy phosphates and creatine kinase synthesis rate under graded isoflurane anesthesia: An in vivo (31) P magnetization transfer study at 11.7 tesla. Magn Reson Med 73:726-30
Muir, Eric R; Chandra, Saurav B; De La Garza, Bryan H et al. (2015) Layer-Specific Manganese-Enhanced MRI of the Diabetic Rat Retina in Light and Dark Adaptation at 11.7 Tesla. Invest Ophthalmol Vis Sci 56:4006-12
Muir, Eric R; Cardenas, Damon; Huang, Shiliang et al. (2014) MRI under hyperbaric air and oxygen: effects on local magnetic field and relaxation times. Magn Reson Med 72:1176-81
Shih, Yen-Yu I; De La Garza, Bryan H; Huang, Shiliang et al. (2014) Comparison of retinal and cerebral blood flow between continuous arterial spin labeling MRI and fluorescent microsphere techniques. J Magn Reson Imaging 40:609-15
Duong, Timothy Q (2014) Magnetic resonance imaging of the retina: from mice to men. Magn Reson Med 71:1526-30
Emeterio Nateras, Oscar San; Harrison, Joseph M; Muir, Eric R et al. (2014) Choroidal blood flow decreases with age: an MRI study. Curr Eye Res 39:1059-67
Zhang, Yi; Harrison, Joseph M; Nateras, Oscar San Emeterio et al. (2013) Decreased retinal-choroidal blood flow in retinitis pigmentosa as measured by MRI. Doc Ophthalmol 126:187-97
Huang, Shiliang; Du, Fang; Shih, Yen-Yu I et al. (2013) Methylene blue potentiates stimulus-evoked fMRI responses and cerebral oxygen consumption during normoxia and hypoxia. Neuroimage 72:237-42
Muir, Eric R; De La Garza, Bryan; Duong, Timothy Q (2013) Blood flow and anatomical MRI in a mouse model of retinitis pigmentosa. Magn Reson Med 69:221-8
Li, Guang; Shih, Yen-Yu Ian; Kiel, Jeffrey W et al. (2013) MRI study of cerebral, retinal and choroidal blood flow responses to acute hypertension. Exp Eye Res 112:118-24

Showing the most recent 10 out of 54 publications