High resolution hyperpolarized ¹³ C MRSI using SPICE at 9.4T.

Area of Science:

• Magnetic Resonance Imaging
• Spectroscopy
• Medical Physics

Background:

• Hyperpolarized (HP) 13C spectroscopic imaging offers metabolic insights but faces technical challenges.
• The SPectroscopic Imaging by exploiting spatiospectral CorrElation (SPICE) technique leverages data properties for improved imaging.
• Assessing SPICE's feasibility for high-resolution HP 13C imaging is crucial for its clinical translation.

Purpose of the Study:

• To evaluate the feasibility of the SPICE technique for high-resolution hyperpolarized 13C spectroscopic imaging.
• To investigate the impact of transient HP signals on SPICE reconstruction accuracy.
• To compare SPICE with conventional echo-planar spectroscopic imaging (EPSI) for HP 13C imaging.

Main Methods:

• Numerical simulations were conducted to assess SPICE reconstruction under varying transient HP signal conditions.
• Simulations compared SPICE and EPSI for HP 13C spectroscopic imaging.
• In vivo experiments utilized HP 13C SPICE on a mouse kidney at 9.4T using HP [1-13C] pyruvate.

Main Results:

• Simulated SPICE showed negligible impact (<4% variation) of transient HP signals on lactate/pyruvate ratios.
• HP 13C SPICE improved the signal-to-noise ratio (SNR) of lactate compared to HP 13C EPSI, enhancing tissue distinction.
• High-resolution in vivo HP 13C spectroscopic imaging of a mouse kidney was successfully acquired, revealing metabolic differences between renal cortices and medullas.

Conclusions:

• HP 13C SPICE is a feasible technique for obtaining high-resolution spectroscopic images with adequate spectral resolution.
• SPICE effectively mitigates SNR limitations seen in conventional EPSI for lactate imaging.
• The study successfully demonstrated the application of HP 13C SPICE in a preclinical in vivo model.