title: Perfusion MRI before and after acetazolamide administration for assessment of cerebrovascular reserve capacity in patients with symptomatic internal carotid artery (ICA) occlusion: comparison with 99mTc-ECD SPECT.
abstract: BACKGROUND
  Impaired cerebral vascular reserve (CVR) in patients with symptomatic internal carotid artery (ICA) occlusion is regarded as a possible indication for performing extra-/intracranial (EC/IC) bypass surgery. As perfusion MR imaging (MRI) can demonstrate cerebral haemodynamics at capillary level, our hypothesis was that perfusion MRI could be used in these patients for the evaluation of CVR following acetazolamide challenge in a similar way to single photon emission CT (SPECT) and might provide additional information.
  
  
  METHODS
  Enrolled in the study were 12 patients (mean age 61.3 years; 11 male, 1 female) with symptomatic unilateral ICA occlusion proven by angiography. Both perfusion MRI and 99m-technetium-ethyl-cysteinate dimer ((99m)Tc-ECD) SPECT were performed before and after injection of acetazolamide (Diamox ,1000 mg i.v.). CVR parameters including regional cerebral blood flow (rCBF) and volume (rCBV), and mean transit times (MTT) were measured by perfusion MRI.
  
  
  RESULTS
  The patients with impaired CVR proven by SPECT (n = 9) had a negative mean rCBF increment (-46.52%), negative rCBV increment (-13.5%) and delayed MTT (mean +2.98 s), respectively, on the occluded side (Student's t-test all P < 0.05). The patients with sufficient CVR (n = 3) had a mean rCBF increment of 1.2%, a decrement of rCBV of 10.46%, and a mean MTT shortening of 0.27 s following the acetazolamide injection.
  
  
  CONCLUSIONS
  Perfusion MRI before and after acetazolamide administration compares favourably with (99m)Tc-ECD SPECT for the detection of impaired CVR. The impact that perfusion MRI studies (before and after acetazolamide administration) might have on the treatment decision in patients with ICA occlusion has yet to be determined by a prospective study.
authors.affiliation: Department of Neuroradiology, Klinikum Grosshadern, University of Munich, 81377 Munich, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.forename: J H
authors.initials: JH
authors.lastname: Mehrkens
authors.forename: M
authors.initials: M
authors.lastname: Holtmannspoetter
authors.forename: R
authors.initials: R
authors.lastname: Linke
authors.forename: R
authors.initials: R
authors.lastname: Schmid-Elsaesser
authors.forename: H-J
authors.initials: HJ
authors.lastname: Steiger
authors.forename: H
authors.initials: H
authors.lastname: Brueckmann
authors.forename: R
authors.initials: R
authors.lastname: Bruening
mesh_terms: D000086:Acetazolamide; D000368:Aged; D002343:Carotid Artery, Internal; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D016009:Chi-Square Distribution; D003545:Cysteine / Q000031:analogs & derivatives*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D012307:Risk Factors; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C059659:technetium Tc 99m bicisate; D003545:Cysteine; D000086:Acetazolamide