title: Susceptibility-Weighted Phase Imaging and Oxygen Extraction Fraction Measurement during Sedation and Sedation Recovery using 7T MRI.
abstract: OBJECTIVE
  In this work, we demonstrate oxygen extraction fraction (OEF) measurement using 7T MRI with susceptibility-weighted imaging (SWI), in sedated and nonsedated adults.
  
  
  METHODS
  Ten healthy subjects (30.3 ± 4.5 years, 9 men, 1 woman) formed control (n = 5) and sedation groups (n = 5). Midazolam and propofol injection was administered to the same sedation group subjects during 2 different scanning sessions. Two-dimensional SPGR imaging was performed before, during, and twice after (propofol, +10, +30 minutes; midazolam, +10, +40 minutes) conscious sedation. The equivalent procedure was performed with the control group without sedation. After SWI analysis, change in OEF between scans was quantified, and parcelated ΔOEF maps were generated with 77 gray matter (GM)-containing volumes-of-interest (VOIs).
  
  
  RESULTS
  Significant decreases in OEF were shown in 14 GM VOIs during sedation relative to the control group, most notably during midazolam sedation (P < .05). In contrast, no significant decrease was observed after 10 minutes and in only 4 VOIs after 40 minutes recovery.
  
  
  CONCLUSIONS
  Significant change in ΔOEF during conscious sedation using midazolam and propofol could be measured using SWI at 7T in vivo. This may be a potentially useful approach for the noninvasive assessment of OEF in the brain on a clinical basis.
authors.affiliation: Division of Ultrahigh Field MRI, Iwate Medical University, Iwate, Japan.|Department of Radiology, Hokkaido University Hospital, Hokkaido, Japan.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Goodwin
authors.affiliation: Division of Ultrahigh Field MRI, Iwate Medical University, Iwate, Japan.|Department of Radiology, Hokkaido University Hospital, Hokkaido, Japan.
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kudo
authors.affiliation: Division of Dental Anesthesiology, Department of Oral and Maxillofacial Surgery, Iwate Medical University, Iwate, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shinohe
authors.affiliation: Division of Ultrahigh Field MRI, Iwate Medical University, Iwate, Japan.
authors.forename: Satomi
authors.initials: S
authors.lastname: Higuchi
authors.affiliation: Division of Ultrahigh Field MRI, Iwate Medical University, Iwate, Japan.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Uwano
authors.affiliation: Division of Ultrahigh Field MRI, Iwate Medical University, Iwate, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Yamashita
authors.affiliation: Division of Ultrahigh Field MRI, Iwate Medical University, Iwate, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Sasaki
mesh_terms: D000328:Adult; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D054810:Deep Sedation / Q000379:methods; D005260:Female; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D018686:Anesthetics, Intravenous; D010100:Oxygen
keywords: 7T MRI; OEF; SWI; midazolam; propofol