Unveiling extracellular inorganic phosphate signals from blood in human cardiac 31P NMR spectra

Area of Science:

• Cardiovascular Physiology
• Magnetic Resonance Imaging
• Biochemistry

Background:

• 31P NMR spectroscopy is crucial for assessing human heart metabolism.
• Blood-derived signals, primarily 2,3-diphosphoglycerate (2,3-DPG), often contaminate cardiac spectra.
• These contaminants obscure signals of myocardial inorganic phosphate, hindering pH and metabolic monitoring.

Purpose of the Study:

• To evaluate the feasibility of obtaining adequate myocardial inorganic phosphate signals without proton decoupling.
• To identify the source of signals in the chemical shift region of the 2-phosphate signal of 2,3-DPG.

Main Methods:

• Acquisition and analysis of 31P NMR spectra from the human heart.
• Assessment of spectral resolution without proton decoupling.
• Identification of signal origins through chemical shift analysis.

Main Results:

• Adequate spectral resolution for evaluating myocardial inorganic phosphate was achieved in approximately 70% of spectra, even without proton decoupling.
• Extracellular inorganic phosphate from blood was identified as a contributor to signals in the chemical shift region of the 2-phosphate signal of 2,3-DPG.

Conclusions:

• Human cardiac 31P NMR spectroscopy can yield interpretable myocardial inorganic phosphate signals without proton decoupling.
• Understanding blood signal contributions, including extracellular inorganic phosphate, is essential for accurate cardiac metabolic assessment.