title: Quantitative oxygen extraction fraction from 7-Tesla MRI phase: reproducibility and application in multiple sclerosis.
abstract: Quantitative oxygen extraction fraction (OEF) in cortical veins was studied in patients with multiple sclerosis (MS) and healthy subjects via magnetic resonance imaging (MRI) phase images at 7 Tesla (7 T). Flow-compensated, three-dimensional gradient-echo scans were acquired for absolute OEF quantification in 23 patients with MS and 14 age-matched controls. In patients, we collected T2*-weighted images for characterization of white matter, deep gray matter, and cortical lesions, and also assessed cognitive function. Variability of OEF across readers and scan sessions was evaluated in a subset of volunteers. OEF was averaged from 2 to 3 pial veins in the sensorimotor, parietal, and prefrontal cortical regions for each subject (total of ~10 vessels). We observed good reproducibility of mean OEF, with intraobserver coefficient of variation (COV)=2.1%, interobserver COV=5.2%, and scan-rescan COV=5.9%. Patients exhibited a 3.4% reduction in cortical OEF relative to controls (P=0.0025), which was not different across brain regions. Although oxygenation did not relate with measures of structural tissue damage, mean OEF correlated with a global measure of information processing speed. These findings suggest that cortical OEF from 7-T MRI phase is a reproducible metabolic biomarker that may be sensitive to different pathologic processes than structural MRI in patients with MS.
authors.affiliation: 1] Massachussets Institute of Technology, Cambridge, Massachusetts, USA [2] Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Audrey P
authors.initials: AP
authors.lastname: Fan
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Sindhuja T
authors.initials: ST
authors.lastname: Govindarajan
authors.affiliation: 1] Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA [2] Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: R Philip
authors.initials: RP
authors.lastname: Kinkel
authors.affiliation: 1] Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA [2] Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Nancy K
authors.initials: NK
authors.lastname: Madigan
authors.affiliation: Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: A Scott
authors.initials: AS
authors.lastname: Nielsen
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Benner
authors.affiliation: Department of Neurology and Psychiatry, University of Rome 'La Sapienza', Rome, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Tinelli
authors.affiliation: 1] Massachussets Institute of Technology, Cambridge, Massachusetts, USA [2] Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA [3] Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Rosen
authors.affiliation: 1] Massachussets Institute of Technology, Cambridge, Massachusetts, USA [2] Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Elfar
authors.initials: E
authors.lastname: Adalsteinsson
authors.affiliation: 1] Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA [2] Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Caterina
authors.initials: C
authors.lastname: Mainero
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D016022:Case-Control Studies; D002550:Cerebral Veins / Q000378:metabolism; D003071:Cognition / Q000502:physiology; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009103:Multiple Sclerosis / Q000378:metabolism* / Q000473:pathology* / Q000523:psychology; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D011446:Prospective Studies; D015203:Reproducibility of Results
chemical_list: D010100:Oxygen