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

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 ofunilateral and bilateral ICAstenosis 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 plusmn; 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.