Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion

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Abstract
Purpose: Compare extracranial internal carotid artery flow rates and intracranial collateral use between conventional ≥ 50% carotid stenosis and carotid near-occlusion, and between symptomatic and asymptomatic carotid near-occlusion. Methods: We included patients with ≥ 50% carotid stenosis. Degree of stenosis was diagnosed on CTA. Mean blood flow rates were assessed with four-dimensional phase-contrast MRI. Results: We included 110 patients of which 83% were symptomatic, and 38% had near-occlusion. Near-occlusions had lower mean internal carotid artery flow (70 ml/min) than conventional ≥ 50% stenoses (203 ml/min, P < .001). Definite use of ≥ 1 collateral was found in 83% (35/42) of near-occlusions and 10% (7/68) of conventional stenoses (P < .001). However, there were no differences in total cerebral blood flow (514 ml/min vs. 519 ml/min, P = .78) or ipsilateral hemispheric blood flow (234 vs. 227 ml/min, P = .52), between near-occlusions and conventional ≥ 50% stenoses, based on phase-contrast MRI flow rates. There were no differences in total cerebral or hemispheric blood flow, or collateral use, between symptomatic and asymptomatic near-occlusions. Conclusion: Near-occlusions have lower internal carotid artery flow rates and more collateral use, but similar total cerebral blood flow and hemispheric blood flow, compared to conventional ≥ 50% carotid stenosis.
Funding Information
  • Knut och Alice Wallenbergs Stiftelse
  • Region Västerbotten
  • Västra Götalandsregionen
  • Hjärt-Lungfonden
  • STROKE-Riksförbundet
  • Jeanssons Stiftelser
  • Svenska Läkaresällskapet
  • The research foundation for neurological research at the University Hospital of Northern Sweden
  • The research foundation for medical research at Umeå University
  • The Northern Swedish Stroke fund
  • Umea University

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