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dc.contributor.authorBrevard, Mathew E.
dc.contributor.authorDuong, Timothy Q.
dc.contributor.authorKing, Jean A.
dc.contributor.authorFerris, Craig F.
dc.date2022-08-11T08:10:27.000
dc.date.accessioned2022-08-23T17:09:26Z
dc.date.available2022-08-23T17:09:26Z
dc.date.issued2003-12-20
dc.date.submitted2010-11-01
dc.identifier.citationMagn Reson Imaging. 2003 Nov;21(9):995-1001.
dc.identifier.issn0730-725X (Linking)
dc.identifier.pmid14684202
dc.identifier.urihttp://hdl.handle.net/20.500.14038/45820
dc.description.abstractMost functional magnetic resonance imaging (fMRI) studies in animals are conducted under anesthesia to minimize motion artifacts. However, methods and techniques have been developed recently for imaging fully conscious rats. Functional MRI studies on conscious animals report enhanced BOLD signal changes as compared to the anesthetized condition. In this study, rats were exposed to different concentrations of carbon dioxide (CO(2)) while conscious and anesthetized to test whether cerebrovascular reactivity may be contributing to these enhanced BOLD signal changes. Hypercapnia produced significantly greater increases in MRI signal intensity in fully conscious animals (6.7-13.3% changes) as when anesthetized with 1% isoflurane (3.2-4.9% changes). In addition, the response to hypercapnia was more immediate in the conscious condition (< 30s) with signal risetimes twice as fast as in the anesthetized state (60s). Both cortical and subcortical brain regions showed a robust, dose- dependent increase in MRI signal intensity with hypercapnic challenge while the animals were conscious but little or no change when anesthetized. Baseline variations in MRI signal were higher while animals were conscious but this was off set by greater signal intensity changes leading to a greater contrast-to-noise ratio, 13.1 in conscious animals, as compared to 8.0 in the anesthetized condition. In summary, cerebral vasculature appears to be more sensitive to hypercapnic challenge in the conscious condition resulting in enhanced T2* MRI signal intensity and the potential for better BOLD signal changes during functional imaging.
dc.language.isoen_US
dc.relation<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=14684202&dopt=Abstract">Link to Article in PubMed</a>
dc.relation.urlhttp://dx.doi.org/10.1046/j.1528-1157.2003.61002.x
dc.subjectAnesthesia
dc.subjectAnimals
dc.subjectCarbon Dioxide
dc.subjectCerebrovascular Circulation
dc.subjectConsciousness
dc.subjectHypercapnia
dc.subject*Magnetic Resonance Imaging
dc.subjectMale
dc.subjectModels, Animal
dc.subjectRats
dc.subjectRats, Sprague-Dawley
dc.subjectPsychiatry
dc.titleChanges in MRI signal intensity during hypercapnic challenge under conscious and anesthetized conditions
dc.typeJournal Article
dc.source.journaltitleMagnetic resonance imaging
dc.source.volume21
dc.source.issue9
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/psych_pp/349
dc.identifier.contextkey1625931
html.description.abstract<p>Most functional magnetic resonance imaging (fMRI) studies in animals are conducted under anesthesia to minimize motion artifacts. However, methods and techniques have been developed recently for imaging fully conscious rats. Functional MRI studies on conscious animals report enhanced BOLD signal changes as compared to the anesthetized condition. In this study, rats were exposed to different concentrations of carbon dioxide (CO(2)) while conscious and anesthetized to test whether cerebrovascular reactivity may be contributing to these enhanced BOLD signal changes. Hypercapnia produced significantly greater increases in MRI signal intensity in fully conscious animals (6.7-13.3% changes) as when anesthetized with 1% isoflurane (3.2-4.9% changes). In addition, the response to hypercapnia was more immediate in the conscious condition (< 30s) with signal risetimes twice as fast as in the anesthetized state (60s). Both cortical and subcortical brain regions showed a robust, dose- dependent increase in MRI signal intensity with hypercapnic challenge while the animals were conscious but little or no change when anesthetized. Baseline variations in MRI signal were higher while animals were conscious but this was off set by greater signal intensity changes leading to a greater contrast-to-noise ratio, 13.1 in conscious animals, as compared to 8.0 in the anesthetized condition. In summary, cerebral vasculature appears to be more sensitive to hypercapnic challenge in the conscious condition resulting in enhanced T2* MRI signal intensity and the potential for better BOLD signal changes during functional imaging.</p>
dc.identifier.submissionpathpsych_pp/349
dc.contributor.departmentDepartment of Psychiatry
dc.source.pages995-1001


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