Regionally resolved cardiac metabolism using a dipole-loop array coil for 7 T ³¹P-MRSI.

Area of Science:

• Cardiovascular Magnetic Resonance Imaging
• Metabolic Imaging
• Biophysics

Background:

• Cardiac metabolism assessment is crucial for understanding heart function.
• Phosphorus-31 magnetic resonance spectroscopic imaging (³¹P-MRSI) provides insights into cellular energetics.
• Novel coil technology is needed to improve the spatial resolution and signal-to-noise ratio (SNR) of cardiac ³¹P-MRSI.

Purpose of the Study:

• To introduce and evaluate a novel commercial phosphorus-31 (³¹P) dipole-loop array coil for cardiac imaging.
• To assess the performance of the coil in phantoms and healthy volunteers.
• To measure regional cardiac metabolism using ³¹P-MRSI at 7 Tesla (7T).

Main Methods:

• Coil hardware was described, and B₁ ⁺ field maps were simulated and measured.
• Seventeen healthy volunteers underwent 7T ³¹P-MRSI scans.
• Reproducibility was assessed, and regional phosphocreatine/γ-adenosine triphosphate (PCr/ATP) ratios were correlated with cardiac strain measurements.

Main Results:

• The dipole-loop array coil demonstrated good B₁ ⁺ uniformity (0.13 ± 0.06 microT/sqrt(W)) around the heart.
• Regional PCr/ATP ratios were measured in four left ventricular regions, consistent with previous studies.
• Intrasession and intersession reproducibility coefficients ranged from 0.22-0.88 and 0.29-0.79, respectively.
• Regional PCr/γATP correlated with circumferential strain, but not radial strain.

Conclusions:

• The novel dipole-loop array coil is a promising tool for human cardiac ³¹P-MRSI at 7T.
• The coil offers improved B₁ ⁺ uniformity and SNR, beneficial for clinical studies of cardiac energetics.
• This technology enables, for the first time, the assessment of regional changes in cardiac energetics across the entire left ventricle.