Vascular space occupancy (VASO) cerebral blood volume-weighted MRI identifies hemodynamic impairment in patients with carotid artery disease

J Magn Reson Imaging. 2009 Mar;29(3):718-24. doi: 10.1002/jmri.21667.

Abstract

Purpose: To assess the role of vascular space occupancy (VASO) magnetic resonance imaging (MRI), a noninvasive cerebral blood volume (CBV)-weighted technique, for evaluating CBV reactivity in patients with internal carotid artery (ICA) stenosis.

Materials and methods: VASO reactivity, defined as a signal change in response to hypercapnic stimulus (4-second exhale, 14-second breath-hold), was measured in the left and right ICA flow territories in patients (n=10) with varying degrees of unilateral and bilateral ICA stenosis and in healthy volunteers (n=10).

Results: Percent VASO reactivity was more negative (P<0.01) bilaterally in patients (ipsilateral: -3.6+/-1.5%; contralateral: -3.4+/-1.2%) compared with age-matched controls (left: -1.9+/-0.6%; right: -1.9+/-0.8%). Owing to the nature of the VASO contrast mechanism, this more negative VASO reactivity was attributed to autoregulatory CBV effects in patients. A postbreath-hold overshoot, which was absent in healthy volunteers, was observed unilaterally in a subset of patients.

Conclusion: More negative VASO reactivity was observed in patients with ICA stenosis and may be a marker of autoregulatory effects. Furthermore, the postbreath-hold overshoot observed in patients is consistent with compensatory microvascular vasoconstriction and may be a marker of hemodynamic impairment. Based on the results of this feasibility study, VASO should be useful for identifying CBV adjustments in patients with steno-occlusive disease of the ICA.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Blood Volume
  • Brain / blood supply*
  • Carotid Artery Diseases / diagnosis
  • Carotid Artery Diseases / physiopathology*
  • Cerebrovascular Circulation*
  • Feasibility Studies
  • Female
  • Hemodynamics
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged