Noninvasive determination of coronary blood flow velocity with magnetic resonance imaging: Comparison of breath-hold and navigator techniques with intravascular ultrasound

Abstract

The aim of this study was to evaluate two different magnetic resonance (MR) techniques for the noninvasive assessment of intracoronary blood flow. Coronary blood flow velocities were measured invasively in 26 angiographically normal segments of 12 patients. Noninvasive measurements were performed in identical segments with two MR techniques using a 1.5 T MR tomograph (ACS NT, Philips). A single breath‐hold technique (temporal resolution: 140 msec) and a similar non‐breath‐hold technique with prospective navigator correction and improved temporal resolution (45 msec) were used. Maximal coronary flow velocities determined by MR correlated closely with invasive measurements (breath‐hold: r = 0.70; navigator: r = 0.86); however, a significant underestimation of the MR measurements was found (slope = 0.33 and 0.37). The relative difference from the invasive method was lower for the navigator technique compared with the breath‐hold technique (P < 0.02). Both MR techniques allow the determination of coronary blood flow velocities. The higher temporal resolution and shorter acquisition window of navigator‐corrected non‐breath‐hold techniques lead to increased accuracy. This approach is a further step toward the diagnostic use of MR flow measurements in coronary artery disease. Magn Reson Med 41:544–549, 1999. © 1999 Wiley‐Liss, Inc.

Coronary vasomotor responses to isometric handgrip exercise are primarily mediated by nitric oxide: a noninvasive MRI test of coronary endothelial function

“…L-NMMA profoundly blocked the normal coronary vasomotor response in only 25 segments in 10 subjects such that it was difficult to justify additional studies, especially with L-NMMA, a nonapproved agent. MRI measures of coronary area (16) and CFV (11,18) were validated in prior studies, and our results are comparable with those reported using invasive techniques (2,15,24). Although systemic L-NMMA infusion caused a slight decrease in heart rate and increase in mean arterial pressure possibly mediated by neurohormonal mechanisms (26), the changes in RPP with IHE stress were not different during the placebo and L-NMMA IHE stress sessions.…”

103 Non-invasive measurement of coronary artery flow velocity at rest and during handgrip stress in healthy subjects using 3 T MRI

“…Scout scans were performed to determine the 3D course and orientation of the proximal right coronary artery (RCA). Baseline coronary velocity measurements were obtained using a VCG triggered breath-hold (11-23 sec) velocityencoded spiral cine sequence perpendicular to the RCA (FOV = 250 × 250 mm 2 , matrix = 312 × 312, spatial resolution = 0.8 × 0.8 × 8 mm 3 , TR = 34 ms, TE = 3.5 ms, RF excitation angle = 20°, spiral acquisition window = 27 ms, spiral interleaves = 11, VENC = 35 cm/s). After baseline imaging, each subject performed isometric handgrip for 3.5 min at 30% of their maximum grip strength on a nonmagnetic, handgrip dynamometer [6].…”

“…In response to endothelialdependent stressors, changes in coronary artery cross-sectional area and flow velocity occur which are typically assessed by invasive methods. Magnetic resonance flow mapping is non-invasive and validated for endothelialindependent stressors in humans by comparison with Doppler guidewire measurements [2,3]. One prior study [4], performed at 1.5 T and recording 7-11 cine frames per cardiac cycle, assessed coronary flow velocity during isometric handgrip exercise, a well-established provocateur of endothelial-dependent vasoreactivity [5].…”

Effect of Pulsatile Flow Waveform and Womersley Number on the Flow in Stenosed Arterial Geometry

“…Magnetic resonance (MR)- [54] and intravascular ultrasound (IVUS)- [55] based techniques have been described to provide valuable diagnostic and anatomical information; however, their temporal and spatial resolution is usually not sufficient for deriving information based on the differentiated velocity vector field such as the wall shear stress distribution [56]. CFD techniques, on the other hand, can provide a significantly larger amount of information on coronary flow dynamics, with greater spatial and temporal resolution, noninvasively, on a patient-specific basis and within a completely virtual environment.…”