title: Age and sex variability and normal reference values for the V(MCA)/V(ICA) index.
abstract: OBJECTIVE
  The index of mean blood flow velocity (V) in the middle cerebral artery (MCA) divided by respective velocity in the ipsilateral internal carotid artery (ICA), or V(MCA)/V(ICA) index, is commonly used as a marker of vasospasm, although reference values are not established. We sought to provide reference data for these velocities and index.
  
  
  METHODS
  Transcranial color-coded duplex and carotid duplex sonography was performed in 335 healthy volunteers (211 women, 124 men; mean age +/- SD, 42 +/- 18 years; range, 18-86 years). Age analyses were based on three groups: I, <40; II, 40-60; and III, >60 years. The V(MCA)/V(ICA) index was calculated based on angle-corrected blood flow velocities determined in the MCA and extracranial ICA.
  
  
  RESULTS
  Mean flow velocities in the MCA and ICA diminished with increasing age, most pronounced in those subjects >40 years. The V(MCA)/V(ICA) index increased significantly (1.67 + 0.005 [age]; P < .05) with age in women, but not in men. In women, reference values and ranges for the V(MCA)/V(ICA) index were as follows, by group: I, 1.82 (range, 0.88-2.68); II, 1.91 (range, 0.94-2.88); and III, 2.06 (range, 0.59-3.53). Respective values for men were as follows, by group: I, 2.10 (range, 0.96-3.24); II, 2.04 (range, 0.71-3.37); and III, 1.78 (range, 0.81-2.75). In subjects <40 years, the V(MCA)/V(ICA) index was significantly higher in men than in women.
  
  
  CONCLUSIONS
  The V(MCA)/V(ICA) index significantly varies with age and sex. Sonographic diagnosis of cerebral vasospasm should be based on age- and sex-adjusted reference values of the V(MCA)/V(ICA) index.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Krejza
authors.forename: Piotr
authors.initials: P
authors.lastname: Szydlik
authors.forename: David S
authors.initials: DS
authors.lastname: Liebeskind
authors.forename: Jan
authors.initials: J
authors.lastname: Kochanowicz
authors.forename: Oleg
authors.initials: O
authors.lastname: Bronov
authors.forename: Zenon
authors.initials: Z
authors.lastname: Mariak
authors.forename: Elias R
authors.initials: ER
authors.lastname: Melhem
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012737:Sex Factors; D017585:Ultrasonography, Doppler, Transcranial