Noninvasive measurements of cardiac high-energy phosphate metabolites in dilated cardiomyopathy by using 31P spectroscopic chemical shift imaging

Abstract

Dilated cardiomyopathy (DCM) is accompanied by an impaired cardiac energy metabolism. The aim of this study was to investigate metabolic ratios in patients with DCM compared to controls by using spectroscopic two-dimensional chemical shift imaging (2D-CSI). Twenty volunteers and 15 patients with severe symptoms (left ventricular ejection fraction, LVEF<30%) and ten patients with moderate symptoms (LVEF>30%) of DCM were investigated. Cardiac 31P MR 2D-CSI measurements (voxel size: 40x40x100 mm3) were performed with a 1.5 T whole-body scanner. Measurement time ranged from 15 min to 30 min. Peak areas and ratios of different metabolites were evaluated, including high-energy phosphates (PCr, ATP), 2,3-diphosphoglycerate (2,3-DPG) and phosphodiesters (PDE). In addition, we evaluated how PCr/ATP ratios correlate with LVEF as an established prognostic factor of heart failure. The PCr/gamma-ATP ratio was significantly decreased in patients with moderate and severe DCM and showed a linear correlation with reduced LVEFs. PDE/ATP ratios were significantly increased only in patients with severe DCM as compared to volunteers. Applying 31P MRS with commonly-available 2D-CSI sequences is a valuable technique to evaluate DCM by determining PCr/ATP ratios noninvasively. In addition to reduced PCr/ATP ratios observed in patients suffering from DCM, significantly-increased PDE/ATP ratios were found in patients with severe DCM.

PET imaging of cardiac hypoxia: Opportunities and challenges

“…31 P magnetic resonance spectroscopy (MRS) is able to determine absolute phosphocreatine and ATP levels in the heart, and measure intracellular pH [48], which are all associated with oxygen or blood flow deficit. Significant reductions of phosphocreatine: ATP ratios have been demonstrated in patients with heart failure [49,50] and hypertrophic cardiomyopathy [51] correlating with declining left ventricular ejection fraction [52]. Similar changes have also been recently demonstrated in healthy volunteers in a normobaric hypoxia chamber [53].…”

64Cu-CTS: A Promising Radiopharmaceutical for the Identification of Low-Grade Cardiac Hypoxia by PET

“…These characteristics mirror the reductions in phosphocreatine-to-ATP ratio previously demonstrated by 31 P MR spectroscopy in patients with heart failure (24,25) and hypertrophic cardiomyopathy (26) and correlate with declining left ventricular ejection fraction and increased mortality (27). Although moderate depletion of cardiac ATP has also been observed in patients diagnosed with hypertrophied and failing myocardium (28), we used a less severe experimental threshold at which phosphocreatine levels were compromised but ATP levels were maintained, to provide a more sensitive means of screening for diagnostically relevant hypoxia-selective complexes.…”

Evaluation of transient apical ballooning with cardiac magnetic resonance imaging and 31-phosphorous magnetic resonance spectroscopy

“…EF improved by 46% and 29%. Myocardial PCr/ATP ratios have been recently correlated to left ventricular EF in heart failure [9] and drug treatment has been shown to be able to improve PCr/ATP ratios in those patients [5]. Whether changes in PCr/ATP ratios are a cause or a consequence of left ventricular function in our study group deserves closer investigation [10].…”