Document Detail


Lamina-specific functional MRI of retinal and choroidal responses to visual stimuli.
MedLine Citation:
PMID:  21447679     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: To demonstrate lamina-specific functional magnetic resonance imaging (MRI) of retinal and choroidal responses to visual stimulation of graded luminance, wavelength, and frequency.
MATERIALS AND METHODS: High-resolution (60 × 60 μm) MRI was achieved using the blood-pool contrast agent, monocrystalline iron oxide nanoparticles (MION) and a high-magnetic-field (11.7 T) scanner to image functional changes in the normal rat retina associated with various visual stimulations. MION functional MRI measured stimulus-evoked blood-volume (BV) changes. Graded luminance, wavelength, and frequency were investigated. Stimulus-evoked fMRI signal changes from the retinal and choroidal vascular layers were analyzed.
RESULTS: MRI revealed two distinct laminar signals that corresponded to the retinal and choroidal vascular layers bounding the retina and were separated by the avascular layer in between. The baseline outer layer BV index was 2-4 times greater than the inner layer BV, consistent with higher choroidal vascular density. During visual stimulation, BV responses to flickering light of different luminance, frequency, and wavelength in the inner layer were greater than those in the outer layer. The inner layer responses were dependent on luminance, frequency, and wavelength, whereas the outer layer responses were not, suggesting differential neurovascular coupling between the two vasculatures.
CONCLUSIONS: This is the first report of simultaneous resolution of layer-specific functional responses of the retinal and choroid vascular layers to visual stimulation in the retina. This imaging approach could have applications in early detection and longitudinal monitoring of retinal diseases where retinal and choroidal hemodynamics may be differentially perturbed at various stages of the diseases.
Authors:
Yen-Yu I Shih; Bryan H De la Garza; Eric R Muir; William E Rogers; Joseph M Harrison; Jeffrey W Kiel; Timothy Q Duong
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2011-07-15
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  52     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-07-18     Completed Date:  2011-09-13     Revised Date:  2012-02-10    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5303-10     Citation Subset:  IM    
Affiliation:
Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Blood Volume
Choroid / blood supply,  physiology*
Contrast Media / administration & dosage
Dose-Response Relationship, Drug
Ferumoxytol / administration & dosage
Magnetic Resonance Imaging*
Male
Nanoparticles / administration & dosage
Photic Stimulation / methods*
Rats
Rats, Sprague-Dawley
Regional Blood Flow
Retina / physiology*
Retinal Vessels / physiology
Grant Support
ID/Acronym/Agency:
EY018855/EY/NEI NIH HHS; R01 EY009702-17/EY/NEI NIH HHS; R01 EY014211/EY/NEI NIH HHS; R01EY09702/EY/NEI NIH HHS
Chemical
Reg. No./Substance:
0/Contrast Media; 0/monocrystalline iron oxide nanoparticle; 1317-61-9/Ferumoxytol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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