title: Changes in blood flow velocity and diameter of the middle cerebral artery during hyperventilation: assessment with MR and transcranial Doppler sonography.
abstract: OBJECTIVE
  To compare blood flow velocity changes within the middle cerebral artery (MCA) during hyperventilation, as measured with by both transcranial Doppler sonography and MR imaging, with the diameter of the MCA as measured with MR imaging alone.
  
  
  METHODS
  The studies were performed in six healthy volunteers ranging in age from 22 to 31 years (mean, 27 years). Transcranial Doppler sonography was carried out with a range-gated 2-MHz transducer. MR examinations were done on a 1.5-T imaging unit. MR angiography was performed using the time-of-flight technique. MR flow measurements were carried out by using the phase-mapping technique with an ECG-triggered phase-contrast sequence.
  
  
  RESULTS
  During hyperventilation, the mean blood flow velocity of the proximal MCA declined by 49.6% +/- 5.7 (mean +/- standard deviation) as measured with Doppler sonography, and by 47% +/- 4.6 as measured with MR flow calculation. The diameter of the MCA (3.4 +/- 0.3 mm) remained unchanged on MR imaging studies (3.3 +/- 0.3 mm).
  
  
  CONCLUSIONS
  We found a good correlation between relative flow velocity changes measured by transcranial Doppler sonography and MR techniques. MR imaging revealed no significant changes in the diameter of the proximal MCA during normal versus hyperventilation. Relative changes in flow velocity in the MCA would thereby reflect relative changes in cerebral blood flow, at least during hyperventilation.
authors.affiliation: Department of Neurology, University Hospital Charité, Humboldt University, Berlin, Germany.
authors.forename: J M
authors.initials: JM
authors.lastname: Valdueza
authors.forename: J O
authors.initials: JO
authors.lastname: Balzer
authors.forename: A
authors.initials: A
authors.lastname: Villringer
authors.forename: T J
authors.initials: TJ
authors.lastname: Vogl
authors.forename: R
authors.initials: R
authors.lastname: Kutter
authors.forename: K M
authors.initials: KM
authors.lastname: Einhäupl
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply*; D002536:Cerebral Arteries / Q000503:physiopathology; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology*; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D012016:Reference Values; D017585:Ultrasonography, Doppler, Transcranial; D014655:Vascular Resistance / Q000502:physiology
chemical_list: D010100:Oxygen