Assessment of Coronary Arterial Flow and Flow Reserve in Humans With Magnetic Resonance Imaging

Abstract

Background The noninvasive measurement of absolute epicardial coronary arterial flow and flow reserve would be useful in the evaluation of patients with coronary circulatory disorders. Phase-contrast magnetic resonance imaging (PC-MRI) has been used to measure coronary arterial flow in animals, but its accuracy in humans is unknown. Methods and Results Twelve subjects (7 men, 5 women; age, 44 to 67 years) underwent PC-MRI measurements of flow in the left anterior descending coronary artery or one of its diagonal branches at rest and after administration of adenosine (140 μg·kg −1 ·min −1 IV). Immediately thereafter, intracoronary Doppler velocity (IDV) and flow measurements were made during cardiac catheterization at rest and after intravenous administration of adenosine. For the 12 patients, the correlation between MRI and invasive measurements of coronary arterial flow and coronary arterial flow reserve was excellent: coronary flow MRI (mL/min)= 0.85×coronary flow IDV (mL/min)+17 (mL/min), r =.89, and coronary flow reserve MRI =0.79×coronary velocity reserve IDV +0.34, r =.89. For the range of coronary arterial flows (18 to 161 mL/min) measured by MRI, the limit of agreement between MRI and catheterization measurements of flow was −13±30 mL/min; for the range of coronary reserves (0.7 to 3.7) measured by MRI, the limit of agreement between the two techniques was 0.1±0.4. Conclusions Cine velocity-encoded PC-MRI can noninvasively measure absolute coronary arterial flow in the left anterior descending artery in humans. PC-MRI can detect pharmacologically induced changes in coronary arterial flow and can reliably distinguish between those subjects with normal and abnormal coronary artery flow reserve.

Phase-Contrast Magnetic Resonance Imaging Measurements of Cerebral Autoregulation With a Breath-Hold Challenge

“…2,32 Furthermore, cardiac MRI studies in acutely ill patients, with expiratory breathholding for artifact reduction, indicate that breath-holding can be performed in clinical settings. 33 In stroke patients, the breath-holding index can be used instead of the percentage flow/velocity increase to account for a submaximal challenge. 8 In the present study, in control subjects, the short (1 minute) time interval between breath-holding periods did not result in VMR differences between the first and the second breath-hold.…”

Coronary Artery Flow Velocity Is Related To Lumen Area and Regional Left Ventricular Mass

“…Nevertheless, many studies have validated APV/2 as a useful approximation of mean velocity. 1,26,27 The assumption of circular arterial cross-sectional area may also introduce some scatter. However, many clinical studies have used circular arterial cross-sectional areas calculated from quantitative coronary diameter measurements.…”

Assessment of Coronary Arterial Restenosis With Phase-Contrast Magnetic Resonance Imaging Measurements of Coronary Flow Reserve

“…13,15,17 At the time of analysis of the MRI data, paired magnitude images and velocity maps were displayed on an image-processing workstation. On the baseline and peak flow image sets, a region of interest (ROI) was generated by manually tracing the vessel lumen on the magnitude image.…”

“…13 Because flow reserve is reduced in patients with restenosis, 4,14 we hypothesized that MRI could be used to identify restenosis in the months after successful percutaneous intervention. To test this hypothesis, we compared MRI measures of CAFR with measures of stenosis severity obtained with computer-assisted quantitative coronary angiography (QCA) in a group of patients with recurrent chest pain after successful percutaneous intervention.…”