title: T2-Imaging to Assess Cerebral Oxygen Extraction Fraction in Carotid Occlusive Disease: Influence of Cerebral Autoregulation and Cerebral Blood Volume.
abstract: OBJECTIVE
  Quantitative T2'-mapping detects regional changes of the relation of oxygenated and deoxygenated hemoglobin (Hb) by using their different magnetic properties in gradient echo imaging and might therefore be a surrogate marker of increased oxygen extraction fraction (OEF) in cerebral hypoperfusion. Since elevations of cerebral blood volume (CBV) with consecutive accumulation of Hb might also increase the fraction of deoxygenated Hb and, through this, decrease the T2'-values in these patients we evaluated the relationship between T2'-values and CBV in patients with unilateral high-grade large-artery stenosis.
  
  
  METHODS
  Data from 16 patients (13 male, 3 female; mean age 53 years) with unilateral symptomatic or asymptomatic high-grade internal carotid artery (ICA) or middle cerebral artery (MCA) stenosis/occlusion were analyzed. MRI included perfusion-weighted imaging and high-resolution T2'-mapping. Representative relative (r)CBV-values were analyzed in areas of decreased T2' with different degrees of perfusion delay and compared to corresponding contralateral areas.
  
  
  RESULTS
  No significant elevations in cerebral rCBV were detected within areas with significantly decreased T2'-values. In contrast, rCBV was significantly decreased (p<0.05) in regions with severe perfusion delay and decreased T2'. Furthermore, no significant correlation between T2'- and rCBV-values was found.
  
  
  CONCLUSIONS
  rCBV is not significantly increased in areas of decreased T2' and in areas of restricted perfusion in patients with unilateral high-grade stenosis. Therefore, T2' should only be influenced by changes of oxygen metabolism, regarding our patient collective especially by an increase of the OEF. T2'-mapping is suitable to detect altered oxygen consumption in chronic cerebrovascular disease.
authors: Department of Neurology, Goethe University Frankfurt, Frankfurt, Germany.
authors: Alexander
authors: http://orcid.org/0000-0002-9502-1984
authors: A
authors: Seiler
authors: Brain Imaging Center, Goethe University Frankfurt, Frankfurt, Germany.
authors: Ralf
authors: R
authors: Deichmann
authors: Department of Neurology, Goethe University Frankfurt, Frankfurt, Germany.
authors: Waltraud
authors: W
authors: Pfeilschifter
authors: Department of Neuroradiology, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany.
authors: Elke
authors: E
authors: Hattingen
authors: Department of Neurology, Goethe University Frankfurt, Frankfurt, Germany.|Department of Neurology, Helios HSK Hospital, Wiesbaden, Germany.
authors: Oliver C
authors: OC
authors: Singer
authors: Institute of Neuroradiology, Goethe University Frankfurt, Frankfurt, Germany.
authors: Marlies
authors: M
authors: Wagner
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D001921:Brain / Q000378:metabolism*; D002343:Carotid Artery, Internal / Q000502:physiology; D016893:Carotid Stenosis / Q000175:diagnosis; D000071937:Cerebral Blood Volume; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020244:Infarction, Middle Cerebral Artery / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D055420:Perfusion Imaging; D012189:Retrospective Studies
chemical_list: D006454:Hemoglobins; D010100:Oxygen