title: Effects of thoracic pressure changes on MRI signals in the brain.
abstract: Cerebrovascular stressors, such as breath holding or CO2 inhalation, cause global magnetic resonance imaging (MRI) signal changes. In this study, we show that intrathoracic pressure changes cause rapid MRI signal alterations that have similar spatial patterns to the changes associated with breath holding or CO2 inhalation. Nine subjects performed the Valsalva maneuver during functional MRI data collection. Expiratory pressures ranged from 10 to 40 mm Hg. Breath holds ending on either inhalation or exhalation were also collected. The maximal and minimal functional MRI (fMRI) signal scaled with thoracic pressure load, and the overall amplitude of responses to the Valsalva varied, depending on brain tissue. Additionally, a Valsalva effort as short as 5 seconds yielded signal changes similar in spatial distribution and magnitude to a 20-second breath hold, suggesting potential applications of the Valsalva maneuver for calibrated fMRI experiments.
authors.affiliation: Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Mental Health, Bethesda, Maryland, USA.
authors.forename: Paula
authors.initials: P
authors.lastname: Wu
authors.affiliation: 1] Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Mental Health, Bethesda, Maryland, USA [2] Functional MRI Facility, National Institute of Mental Health, Bethesda, Maryland, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Bandettini
authors.affiliation: 1] Department of Neurobiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA [2] Brain Research Institute, University of California at Los Angeles, Los Angeles, California, USA.
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Harper
authors.affiliation: Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Mental Health, Bethesda, Maryland, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Handwerker
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply; D062485:Breath Holding; D002245:Carbon Dioxide / Q000378:metabolism*; D002560:Cerebrovascular Circulation; D006339:Heart Rate; D006801:Humans; D006935:Hypercapnia / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011312:Pressure; D012119:Respiration; D014636:Valsalva Maneuver; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide