title: BOLD fMRI of cerebrovascular reactivity in the middle cerebral artery territory: A 100 volunteers' study.
abstract: OBJECTIVE
  The assessment of cerebrovascular reactivity (CVR) has shown promising results for its use in medical diagnosis and prognosis, especially in patients suffering from severe intracranial arterial stenosis. However, its quantification remains uncertain because of a large variability inherent in brain anatomy and in methodological settings. To overcome this variability, we provide lateralization index (LI) values for CVR within the middle cerebral artery territory to detect CVR impairment.
  
  
  METHODS
  We assessed CVR in 100 volunteers (41 females; 47.52 ± 21.58 years) without cervico-encephalic arterial stenosis using BOLD-fMRI contrast with a block-design hypercapnic challenge. Averaged end-tidal CO2 was used as a physiological regressor for statistical analyses with a general linear model. We measured %BOLD signal-change in segmented gray matter regions of interest in the middle cerebral artery territory (MCA). We calculated a laterality index according to the following formula: LI=(CVRleft-CVRright)/(CVRleft+CVRright). We tested the effects of methodological settings (i.e. hypercapnic gas, gas administration means, MR acquisition and sex) on %BOLD signal change and LI values with analysis of variance.
  
  
  RESULTS
  No adverse effects of the hypercapnic challenge were reported. LI values were independent of experimental conditions. Mean LI calculated in MCA territories was 0.016 ± 0.031, giving the lower and upper limits of 95% (m ± 2SD) of this population distribution at]-0.05; 0.08[.
  
  
  CONCLUSIONS
  LI can effectively help us to overcome measurement variabilities. Therefore, it can be used to detect abnormal asymmetries in CVR and identify patients at higher risk of ischemic stroke.
authors.affiliation: Université Grenoble Alpes 3bis, CNRS, LPNC, 38000 Grenoble, France; Université Savoie 3, LPNC, 73000 Chambéry, France. Electronic address: naila.boudiaf@gmail.com.
authors.forename: Naïla
authors.initials: N
authors.lastname: Boudiaf
authors.affiliation: Inserm, université Grenoble Alpes, GIN, CHU de Grenoble, 38000 Grenoble, France; Department of Neuroradiology and MRI, University Hospital of Grenoble-IFR1, Grenoble, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Attyé
authors.affiliation: Inserm, université Grenoble Alpes, GIN, CHU de Grenoble, 38000 Grenoble, France.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Warnking
authors.affiliation: Inserm, université Grenoble Alpes, GIN, CHU de Grenoble, 38000 Grenoble, France; Inserm, université Grenoble Alpes, CNRS, IRMaGe, CHU de Grenoble, 38000 Grenoble, France.
authors.forename: Irène
authors.initials: I
authors.lastname: Troprès
authors.affiliation: Inserm, université Grenoble Alpes, CNRS, IRMaGe, CHU de Grenoble, 38000 Grenoble, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Lamalle
authors.affiliation: Inserm, université Grenoble Alpes, CNRS, IRMaGe, CHU de Grenoble, 38000 Grenoble, France.
authors.forename: Johan
authors.initials: J
authors.lastname: Pietras
authors.affiliation: Inserm, université Grenoble Alpes, GIN, CHU de Grenoble, 38000 Grenoble, France; Inserm, université Grenoble Alpes, CNRS, IRMaGe, CHU de Grenoble, 38000 Grenoble, France; Department of Neuroradiology and MRI, University Hospital of Grenoble-IFR1, Grenoble, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Krainik
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging*; D001931:Brain Mapping / Q000379:methods; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D014838:Volunteers
keywords: BOLD-fMRI; Cerebral vascular reactivity; Hypercapnia; Middle cerebral artery stenosis