Dynamic volumetric hyperpolarized ¹³ C imaging with multi-echo EPI.

Area of Science:

• Medical Imaging
• Metabolic Imaging
• Hyperpolarized MRI

Background:

• Dynamic metabolic imaging provides insights into cellular function.
• Current methods for mapping hyperpolarized tracers have limitations in resolution and speed.

Purpose of the Study:

• To develop and validate a method for generating dynamic, volumetric maps of hyperpolarized [1-13C]pyruvate and its metabolic products in vivo.
• To assess the efficacy of iterative least squares (IDEAL) reconstruction for this purpose.

Main Methods:

• Iterative least squares (IDEAL) reconstruction was applied to multiecho echo-planar imaging (EPI) data.
• Phantoms and mice injected with hyperpolarized [1-13C]pyruvate were imaged on a preclinical 3T scanner.
• Image quality was evaluated by assessing the separation of chemical species and generating time course and area-under-the-curve plots.

Main Results:

• Increased EPI shots (one to four) improved IDEAL decomposition and chemical species separation.
• Dynamic 3D metabolite maps of pyruvate and its products (pyruvate hydrate, lactate, bicarbonate, alanine) were successfully generated in live mice.
• Time course and area-under-the-curve graphs for the heart, kidneys, and liver showed good agreement with existing literature.

Conclusions:

• IDEAL decomposition of multishot multiecho 13C EPI is a robust method for high-quality dynamic volumetric mapping of hyperpolarized [1-13C]pyruvate and its metabolites.
• This technique has significant potential for assessing multiorgan metabolic phenomena in vivo.