Cardiac metabolic imaging using hyperpolarized [1-¹³ C]lactate as a substrate

Area of Science:

• Medical Imaging
• Metabolic Imaging
• Cardiovascular Research

Background:

• Hyperpolarized (HP) [1-¹³ C]lactate is a potential alternative to [1-¹³ C]pyruvate for cardiac metabolism studies.
• HP lactate can be safely administered at higher doses and polarized effectively.
• Previous HP lactate cardiac studies were limited to small animal models.

Purpose of the Study:

• To evaluate HP [1-¹³ C]lactate as a substrate for cardiac metabolism imaging in a large animal model.
• To compare the performance of HP [1-¹³ C]lactate with HP [1-¹³ C]pyruvate in porcine hearts.

Main Methods:

• Utilized dynamic nuclear polarization for substrate polarization.
• Acquired ¹³ C metabolic images in porcine hearts following injections of HP [1-¹³ C]lactate and HP [1-¹³ C]pyruvate.
• Employed hardware and data acquisition methods similar to the first human HP ¹³ C cardiac study.

Main Results:

• ¹³ C bicarbonate signal was localized to the myocardium with both substrates.
• No ¹³ C pyruvate signal was detected after HP ¹³ C lactate injection.
• HP lactate showed a signal-to-noise ratio of 88% compared to pyruvate.
• Bicarbonate signal SNR was 52% with lactate versus pyruvate, likely due to lactate's shorter T₁ and an extra metabolic step.

Conclusions:

• HP [1-¹³ C]lactate can be successfully used for cardiac metabolism imaging in a large animal model.
• Despite lower SNR, HP lactate demonstrates potential as a clinical substrate for human heart metabolic imaging.
• Further optimization may be needed to overcome SNR limitations for clinical translation.