Research ArticleCARDIAC IMAGING

Accurate needle-free assessment of myocardial oxygenation for ischemic heart disease in canines using magnetic resonance imaging

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Science Translational Medicine  29 May 2019:
Vol. 11, Issue 494, eaat4407
DOI: 10.1126/scitranslmed.aat4407

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BOLD-hearted

Atherosclerosis and other conditions can restrict the flow of blood to the heart, resulting in tissue damage and ischemic heart disease (IHD). Yang et al. used repeat hypercapnia (transient elevation in carbon dioxide) during cardiac magnetic resonance imaging to detect myocardial oxygenation in a model of IHD in canines. Without relying on exogenous contrast agents, this blood oxygen level–dependent (BOLD) imaging method could map regions of the heart affected by coronary narrowing. Combined with a computational framework that reduces noise, the authors demonstrated the ability to perform noninvasive, rapid, whole-heart imaging under free-breathing conditions, suggesting that this technique may be useful for monitoring myocardial ischemia.

Abstract

Myocardial oxygenation—the ability of blood vessels to supply the heart muscle (myocardium) with oxygen—is a critical determinant of cardiac function. Impairment of myocardial oxygenation is a defining feature of ischemic heart disease (IHD), which is caused by pathological conditions that affect the blood vessels supplying oxygen to the heart muscle. Detecting altered myocardial oxygenation can help guide interventions and prevent acute life-threatening events such as heart attacks (myocardial infarction); however, current diagnosis of IHD relies on surrogate metrics and exogenous contrast agents for which many patients are contraindicated. An oxygenation-sensitive cardiac magnetic resonance imaging (CMR) approach used previously to demonstrate that CMR signals can be sensitized to changes in myocardial oxygenation showed limited ability to detect small changes in signals in the heart because of physiologic and imaging noise during data acquisition. Here, we demonstrate a CMR-based approach termed cfMRI [cardiac functional magnetic resonance imaging (MRI)] that detects myocardial oxygenation. cfMRI uses carbon dioxide for repeat interrogation of the functional capacity of the heart’s blood vessels via a fast MRI approach suitable for clinical adoption without limitations of key confounders (cardiac/respiratory motion and heart rate changes). This method integrates multiple whole-heart images within a computational framework to reduce noise, producing confidence maps of alterations in myocardial oxygenation. cfMRI permits noninvasive monitoring of myocardial oxygenation without requiring ionizing radiation, contrast agents, or needles. This has the potential to broaden our ability to noninvasively identify IHD and a diverse spectrum of heart diseases related to myocardial ischemia.

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