Measurement of coronary blood flow velocity during handgrip exercise using breath-hold velocity encoded cine magnetic resonance imaging

Since the first clinical application of the concept of coronary flow reserve, defined as the ratio of hyperemic flow to flow at rest, for the assessment of significance of coronary artery disease,(1-3) several studies have been performed using various invasive and noninvasive techniques to determine coronary flow reserve in humans.(4-7) With the introduction of rapid, segmented k-space breathholding techniques, visualization of the left and right coronary arteries has become possible.(8,9) Additionally, the introduction of time-of-flight and phase-contrast techniques allows noninvasive blood flow velocity measurements in the coronary arteries in vivo.(10-13) A recent study demonstrated the feasibility of fast velocity encoded cine magnetic resonance imaging (MRI) with k-space segmentation and view sharing reconstruction for displaying phasic coronary flow velocity curve in the cardiac cycle.(14) The purpose of the present study was to assess the applicability of breathhold velocity encoded cine (VEC)-MRI for measuring the increase in coronary blood flow velocity in response to interventions in normal subjects.