Combined native magnetic resonance angiography, flow-quantifying, and perfusion-imaging for impending second-stroke assessment

Atherosclerotic carotid artery disease is the leading cause of ischemic stroke. Spencer and Reid first postulated the hemodynamic impact of stenosis within a vessel as a curve that predicts no substantive decline in flow until approximately 70% stenosis and a steep threshold for flow restriction at approximately 80% stenosis (1). Carotid stenosis risk appears to largely correspond to these thresholds, where moderate (50–69%) stenosis has a more benign prognosis than severe stenosis, and a progressive increase in stroke risk is associated with a degree of stenosis beyond 70%. Magnetic resonance imaging (MRI) is used widely in clinical diagnoses to reveal arterial stenosis noninvasively