MR Derived Volumetric Flow Rate Waveforms at Locations within the Common Carotid, Internal Carotid, and Basilar Arteries

Abstract

The volumetric flow rate (VFR) waveform over the cardiac cycle in the cerebral vasculature is a significant factor in many studies, which involve cerebrovascular function. Perhaps contrary to expectation, the literature in this area is sparse and the characteristics of blood flow waveforms are ill defined. A better understanding of the variation of blood flow rate and pulsatility may aid our knowledge of risk factors involved in diseases and conditions, such as stroke, arteriovenous malformation, or aneurysm rupture. This study sought to characterise the blood flow waveform over the cardiac cycle at levels within the carotid artery and basilar artery (BA) in a normal cohort. The study cohort consisted of 22 subjects (recruitment age: 20 to 40 years) with no history of vascular disease (median age=26 years, interquartile range=25 to 32 years). Two-dimensional quantitative phase-contrast magnetic resonance imaging was performed on each subject at nine anatomic locations within the carotid artery and BA. Significant differences in pulsatility were present within the carotid tree. Archetypal VFR waveforms were established for this group at the nine locations. A normal individual's VFR waveform at a location within the carotid tree can be estimated by taking the group's archetypal waveform for that location, and scaling by the individual's average flow rate.