Coronary flow and coronary flow reserve measurements in humans with breath‐held magnetic resonance phase contrast velocity mapping

Abstract

Objective evidence for coronary lesion significance can be obtained with ischemic stress testing. Since flow-limiting stenoses have already undergone compensatory vasodilatation to maintain flow, the response to vasoactive stimulation is dampened. The degree of response limitation is reflected by the coronary flow reserve (CFR). Absolute volume flow rates can be accurately and noninvasively measured with MRI techniques. The purpose was to assess the ability to measure coronary volume flow rate noninvasively, and characterize the effect of pharmacologic stress on coronary flow quantitatively by using ultrafast, breath-held segmented k-space phase-contrast-MR imaging (PC-MRI). Ten healthy volunteers were examined by using ultrafast breath-held PC-MRI. Coronary volume flow rates were measured in the anterior descending coronary artery (LAD) at rest and following intravenous administration of dipyridamole. CFR was determined based on these data. Mean LAD volume flow rates increased from 38 +/- 11 ml/min before application of dipyridamole to 169 +/- 42 ml/min. The mean CFR amounted to 5.0 +/- 2.6 (median = 4.15). This study demonstrates the feasibility of breath-held PC-MRI to noninvasively quantify coronary volume flow rates over the cardiac cycle. Pharmacologically induced changes in volume flow rate and thus CFR can be quantitated.

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

“…In 1993 Edelman et al (2) demonstrated for the first time that blood flow velocity can be determined noninvasively in human coronary arteries with MR, however, only a single mid diastolic value was obtained (2). Since then, the technique has been optimized and compared with invasive measurements of flow or flow reserve (3,5,7,25,26). Most previous investigators have used breath-hold techniques for noninvasive flow measurements.…”

“…The utilization of phased array coils will improve signal-to-noise ratio, allow higher spatial resolution and make the analysis of the circumflex artery possible. Improved magnets will enable the routine use of echoplanar imaging techniques, which have already been shown to allow flow measurements in small vessels with high temporal resolution (25). A further optimization of navigator techniques will decrease scan time without loss of image quality (34).…”

Blood flow measurements with magnetic resonance phase velocity mapping

“…Consequently, the acquisi tion can be performed in seconds instead of min utes, with high temporal and spatial resolution [60][61][62][63][64]. If velocity-encoding gradients are added to the regular sequence, the flow velocity can be measured rapidly.…”

Ultrafast Flow Quantification With Segmented k-Space Magnetic Resonance Phase Velocity Mapping

“…TGE has shown better flow behavior and is, therefore, more promising for reliable ultrafast flow quantification with relatively disturbed flow and significant vessel motion (e.g., coronary arteries). 9,10,14,20,25 In addition, previous in vitro and clinical studies 2,10,11,14,19,20,23,25,28,29 evaluating both EPI and TGE techniques for PVM have indicated that TGE is generally superior in terms of temporal and (sub-millimeter…”