Quantification of global myocardial oxygenation in humans: initial experience

Abstract

PurposeTo assess the feasibility of our newly developed cardiovascular magnetic resonance (CMR) methods to quantify global and/or regional myocardial oxygen consumption rate (MVO2) at rest and during pharmacologically-induced vasodilation in normal volunteers.MethodsA breath-hold T2 quantification method is developed to calculate oxygen extraction fraction (OEF) and MVO2 rate at rest and/or during hyperemia, using a two-compartment model. A previously reported T2 quantification method using turbo-spin-echo sequence was also applied for comparison. CMR scans were performed in 6 normal volunteers. Each imaging session consisted of imaging at rest and during adenosine-induced vasodilation. The new T2 quantification method was applied to calculate T2 in the coronary sinus (CS), as well as in myocardial tissue. Resting CS OEF, representing resting global myocardial OEF, and myocardial OEF during adenosine vasodilation were then calculated by the model. Myocardial blood flow (MBF) was also obtained to calculate MVO2, by using a first-pass perfusion imaging approach.ResultsThe T2 quantification method yielded a hyperemic OEF of 0.37 ± 0.05 and a hyperemic MVO2 of 9.2 ± 2.4 μmol/g/min. The corresponding resting values were 0.73 ± 0.05 and 5.2 ± 1.7 μmol/g/min respectively, which agreed well with published literature values. The MVO2 rose proportionally with rate-pressure product from the rest condition. The T2 sensitivity is approximately 95% higher with the new T2 method than turbo-spin-echo method.ConclusionThe CMR oxygenation method demonstrates the potential for non-invasive estimation of myocardial oxygenation, and should be explored in patients with altered myocardial oxygenation.

Myocardial Oxygenation Imaging: New Methods for Ischemia Detection

“…Despite this early success for the quantification of myocardial OEF and MVO 2 during hyperemia, measuring OEF and MVO 2 by CMR at rest remains a challenge. Recently, McCommis et al [45] reported measurements of global OEF and MVO 2 in volunteers using a quantitative T 2 -preparation method and the results agreed favorably with other literature values. These techniques may allow comprehensive evaluation of alternations of myocardial oxygenation in the pathophysiology of subjects with myocardial ischemia [46].…”

Oxygenation-sensitive cardiovascular magnetic resonance

“…The change of the myocardial consumption rate has been measured in volunteers using a single breath-hold T2 mapping technique [22]. …”

Emerging roles for integrated imaging modalities in cardiovascular cell-based therapeutics: a clinical perspective

“…Surveillance of regional contractile and diastolic function, infarct size and fibrosis burden may be especially prudent as these parameters can uncover early or subtle benefits from therapy before there is global improvement in cardiac performance [140, 141]. Other measurable indices may also emerge as having important implications for cell engraftment, such as microvascular obstruction, myocardial blood flow, haemorrhage, oedema, area at risk and oxygenation [142, 143]. …”