Hyperpolarized [2-¹³C]pyruvate MR molecular imaging with whole brain coverage

Area of Science:

• Neuroscience
• Biochemistry
• Medical Imaging

Background:

• Cerebral energy metabolism is crucial for brain function.
• Previous imaging techniques had limitations in quantifying metabolic pathways in vivo.
• Hyperpolarized (HP) ¹³C Magnetic Resonance Imaging (MRI) offers enhanced sensitivity for metabolic studies.

Purpose of the Study:

• To apply HP ¹³C MRI for the first time to image and quantify [2-¹³C]pyruvate uptake and metabolism in the human brain.
• To provide novel metabolic information on cerebral energy metabolism.
• To simultaneously investigate glycolytic and oxidative metabolism.

Main Methods:

• Utilized HP [2-¹³C]pyruvate injected intravenously in 5 healthy volunteers.
• Employed a specialized spectral-spatial multi-slice echoplanar imaging (EPI) pulse sequence for whole-brain coverage within a 1-minute acquisition.
• Acquired dynamic and volumetric ¹³C-labeled images of pyruvate and its metabolites, including [5-¹³C]glutamate and [2-¹³C]lactate.

Main Results:

• Successfully imaged and quantified ¹³C-labeled pyruvate, glutamate, and lactate in the human brain.
• Calculated metabolic ratios and apparent conversion rates, such as pyruvate-to-lactate (k_PL) and pyruvate-to-glutamate (k_PG).
• Demonstrated the feasibility of simultaneously assessing glycolytic and oxidative metabolism in a single injection.

Conclusions:

• HP ¹³C MRI is a powerful tool for non-invasive metabolic imaging of the human brain.
• This technique provides quantitative insights into cerebral energy metabolism, including glycolysis and oxidative pathways.
• The study establishes a foundation for future clinical applications in neurological disorders affecting brain metabolism.