Abstract
BackgroundA velocity-selective binomial excitation scheme for myocardial first-pass perfusion measurements with hyperpolarized 13C substrates, which preserves bolus magnetization inside the blood pool, is presented. The proposed method is evaluated against gadolinium-enhanced 1H measurements in-vivo.MethodsThe proposed excitation with an echo-planar imaging readout was implemented on a clinical CMR system. Dynamic myocardial stress perfusion images were acquired in six healthy pigs after bolus injection of hyperpolarized 13C urea with the velocity-selective vs. conventional excitation, as well as standard 1H gadolinium-enhanced images. Signal-to-noise, contrast-to-noise (CNR) and homogeneity of semi-quantitative perfusion measures were compared between methods based on first-pass signal-intensity time curves extracted from a mid-ventricular slice. Diagnostic feasibility is demonstrated in a case of septal infarction.ResultsVelocity-selective excitation provides over three-fold reduction in blood pool signal with a two-fold increase in myocardial CNR. Extracted first-pass perfusion curves reveal a significantly reduced variability of semi-quantitative first-pass perfusion measures (12–20%) for velocity-selective excitation compared to conventional excitation (28–93%), comparable to that of reference 1H gadolinium data (9–15%). Overall image quality appears comparable between the velocity-selective hyperpolarized and gadolinium-enhanced imaging.ConclusionThe feasibility of hyperpolarized 13C first-pass perfusion CMR has been demonstrated in swine. Comparison with reference 1H gadolinium data revealed sufficient data quality and indicates the potential of hyperpolarized perfusion imaging for human applications.
Highlights
A velocity-selective binomial excitation scheme for myocardial first-pass perfusion measurements with hyperpolarized 13C substrates, which preserves bolus magnetization inside the blood pool, is presented
Conventional first-pass perfusion Cardiovascular Magnetic Resonance (CMR) [5] is based on dynamic contrast enhancement (DCE) of saturation recovery [6] in response to bolus administration of a chelated gadolinium based contrast agent
Residual signal is observed at the tube boundary, where velocities deviate from the nominal value
Summary
A velocity-selective binomial excitation scheme for myocardial first-pass perfusion measurements with hyperpolarized 13C substrates, which preserves bolus magnetization inside the blood pool, is presented. Cardiovascular Magnetic Resonance (CMR) perfusion imaging is widely used for the clinical assessment of myocardial ischemia and has proven its excellent diagnostic value [1]. To increase the sensitivity and specificity of detecting perfusion defects, imaging under pharmacologically induced stress is performed, followed by an optional measurement under rest condition [2]. Stress is typically induced by administration of adenosine [3] or dobutamine [4]. Conventional first-pass perfusion CMR [5] is based on dynamic contrast enhancement (DCE) of saturation recovery [6] in response to bolus administration of a chelated gadolinium based contrast agent. Using dual-bolus [8] or dualsequences approaches [9] this issue can be addressed, but adds to complexity of data acquisition and analysis
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