title: Dynamic alteration of regional cerebral blood flow during carotid compression and proof of reversibility.
abstract: BACKGROUND
  It is difficult to non-invasively visualize changes in regional cerebral blood flow caused by manual compression of the carotid artery.
  
  
  OBJECTIVE
  To visualize dynamic changes in regional cerebral blood flow during and after manual compression of the carotid artery.
  
  
  METHODS
  Two healthy volunteers were recruited. Anatomic features and flow directions in the circle of Willis were evaluated with time-of-flight magnetic resonance angiography (MRA) and two-dimensional phase-contrast (2DPC) MRA, respectively. Regional cerebral blood flow was visualized with territorial arterial spin-labeling magnetic resonance imaging (TASL-MRI). TASL-MRI and 2DPC-MRA were performed in three states: at rest, during manual compression of the right carotid artery, and after decompression. In one volunteer, time-space labeling inversion pulse (Time-SLIP) MRA was performed to confirm collateral flow.
  
  
  RESULTS
  During manual carotid compression, in one volunteer, the right thalamus changed to be fed only by the vertebrobasilar system, and the right basal ganglia changed to be fed by the left internal carotid artery. In the other volunteer, the right basal ganglia changed to be fed by the vertebrobasilar system. 2DPC-MRA showed that the flow direction changed in the right A1 segment of the anterior cerebral artery and the right posterior communicating artery. Perfusion patterns and flow directions recovered after decompression. Time-SLIP MRA showed pial vessels and dural collateral circulation when the right carotid artery was manually compressed.
  
  
  CONCLUSIONS
  Use of TASL-MRI and 2DPC-MRA was successful for non-invasive visualization of the dynamic changes in regional cerebral blood flow during and after manual carotid compression.
authors.affiliation: Department of Radiology, Juntendo University School of Medicine , Tokyo , Japan.
authors.forename: Kouichi
authors.initials: K
authors.lastname: Asahi
authors.forename: M
authors.initials: M
authors.lastname: Hori
authors.forename: N
authors.initials: N
authors.lastname: Hamasaki
authors.forename: S
authors.initials: S
authors.lastname: Sato
authors.forename: H
authors.initials: H
authors.lastname: Nakanishi
authors.forename: R
authors.initials: R
authors.lastname: Kuwatsuru
authors.forename: K
authors.initials: K
authors.lastname: Sasai
authors.forename: S
authors.initials: S
authors.lastname: Aoki
keywords: Territorial arterial spin-labeling magnetic resonance imaging (TASL-MRI); manual carotid artery compression; regional cerebral blood flow; two-dimensional phase-contrast MRA (2DPC-MRA)