title: Signal changes on magnetic resonance perfusion images with arterial spin labeling after carotid endarterectomy.
abstract: BACKGROUND
  Cerebral hyperperfusion after carotid endarterectomy (CEA) is defined as an increase in ipsilateral cerebral blood flow (CBF). Practically, however, prompt and precise assessment of cerebral hyperperfusion is difficult because of limitations in the methodology of CBF measurement during the perioperative period. Arterial spin labeling (ASL) is a completely noninvasive and repeatable magnetic resonance perfusion imaging technique that uses magnetically-labelled blood water as an endogenous tracer. To clarify the usefulness of ASL in the management of cerebral hyperperfusion, we investigated signal changes by ASL with a single 1.5-s post-labeling delay on visual inspection.
  
  
  METHODS
  Thirty-two consecutive patients who underwent CEA were enrolled in this retrospective study.
  
  
  RESULTS
  On postoperative day 1, 22 (68.8%) and 4 (12.5%) patients exhibited increased ASL signals bilaterally (Group A) and on the operated side (Group B), respectively. Follow-up ASL showed improvement in these findings. Six (18.8%) patients showed no change (Group C). There was no apparent correlation between ASL signals on postoperative day 1 and the preoperative hemodynamic state, including the cerebrovascular reserve (P= 0.2062). Three (9.4%) patients developed cerebral hyperperfusion syndrome (two in Group A and one in Group B). Coincidence in the localization of increased ASL signals and electroencephalographic abnormalities was noted in these patients.
  
  
  CONCLUSIONS
  Visual analysis of ASL with a single post-labeling delay overestimates CBF and cannot identify patients at risk of cerebral hyperperfusion syndrome probably because of the strong effect of the shortened arterial transit time immediately after CEA. However, ASL may be used as for screening.
authors.affiliation: Department of Neurosurgery, Kyushu Rosai Hospital, Kitakyushu, Japan; Department of Neurosurgery, Fukuoka Children's Hospital, Fukuoka, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Shimogawa
authors.affiliation: Department of Neurosurgery, Kyushu Rosai Hospital, Kitakyushu, Japan; Department of Neurosurgery, Fukuoka Children's Hospital, Fukuoka, Japan.
authors.forename: Takato
authors.initials: T
authors.lastname: Morioka
authors.affiliation: Department of Neurosurgery, Kyushu Rosai Hospital, Kitakyushu, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Sayama
authors.affiliation: Department of Neurosurgery, Kyushu Rosai Hospital, Kitakyushu, Japan.
authors.forename: Sei
authors.initials: S
authors.lastname: Haga
authors.affiliation: Department of Neurosurgery, Kyushu Rosai Hospital, Kitakyushu, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Akiyama
authors.affiliation: Department of Cerebrovascular Disease, Kyushu Rosai Hospital, Kitakyushu, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Murao
authors.affiliation: Department of Cerebrovascular Disease, Kyushu Rosai Hospital, Kitakyushu, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kanazawa
authors.affiliation: Department of Cerebrovascular Disease, Kyushu Rosai Hospital, Kitakyushu, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Furuta
authors.affiliation: Department of Clinical Chemistry and Laboratory Medicine, Kyusyu University Hospital, Fukuoka, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Sakata
authors.affiliation: Department of Cerebrovascular Disease, Kyushu Rosai Hospital, Kitakyushu, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Arakawa
keywords: Arterial spin labeling; carotid endarterectomy; cerebral hyperperfusion; cerebral hyperperfusion syndrome