Imaging considerations for in vivo 13C metabolic mapping using hyperpolarized 13C-pyruvate

Area of Science:

• Medical Imaging
• Biophysics
• Metabolic Imaging

Background:

• Hyperpolarized 13C-pyruvate metabolic imaging offers insights into cellular metabolism.
• Challenges exist in optimizing signal-to-noise ratio (SNR) and image quality due to varying signal kinetics of pyruvate and its metabolites (lactate, alanine).

Purpose of the Study:

• To evaluate strategies for improving SNR and image quality in hyperpolarized 13C-pyruvate metabolic imaging.
• To assess the impact of acquisition parameters on multishot fast chemical shift imaging (CSI) and 3D echo-planar spectroscopic imaging (3DEPSI) sequences.

Main Methods:

• Mathematical simulations and rat experiments were conducted using multishot fast CSI and 3DEPSI sequences.
• Acquisition timing was optimized for peak lactate production.
• Strategies evaluated included variable flip angles, centric phase encoding (cPE), EPSI waveform design (flyback vs. symmetric), and spectral bandwidth (BW).

Main Results:

• Combining variable flip angles and cPE enhanced image quality while maintaining good SNR.
• Symmetric EPSI and reduced spectral bandwidth (BW) showed a trend towards increased SNR.
• Optimized imaging strategies were identified for improved metabolic imaging.

Conclusions:

• The evaluated imaging strategies provide guidance for optimizing hyperpolarized 13C-pyruvate metabolic imaging protocols.
• Specific parameter choices can significantly enhance SNR and image quality for better metabolic assessment.