Hyperpolarized [1-¹³C]-acetate Renal Metabolic Clearance Rate Mapping

Area of Science:

• Medical Imaging
• Biochemistry
• Physiology

Background:

• Carbon-11 acetate (PET) and hyperpolarized carbon-13 acetate (MRI) are tracers for oxidative metabolism.
• Understanding kidney metabolic processes requires comparable kinetic formalisms between PET and MRI.

Purpose of the Study:

• To compare the kinetic formalism of 11C-acetate PET and 13C-acetate MRI in the kidneys.
• To compare dynamic metabolic information obtained from hyperpolarized 13C-acetate MRI and 11C-acetate PET.

Main Methods:

• Dynamic hyperpolarized 13C-acetate MRI and 11C-acetate PET were performed on rats before and after furosemide administration.
• Metabolic clearance rates (MCR) were estimated and compared between modalities in vivo and via simulations.

Main Results:

• Both 13C-acetate and 11C-acetate showed dependency on mean transit time and MCR after furosemide.
• No dependency on apparent renal perfusion was observed for either tracer.
• Metabolic clearance rates (MCR) measured by both modalities were correlated.

Conclusions:

• Hyperpolarized 13C-acetate MRI is feasible for measuring intrarenal energetic demand via MCR.
• Quantitative measures from 13C-acetate MRI correlate with 11C-acetate PET findings.
• This validates MRI as a comparable, albeit temporally different, tool for metabolic assessment.