High-Resolution Dynamic ³¹P-MR Spectroscopic Imaging for Mapping Mitochondrial Function.

Area of Science:

• Biomedical Engineering
• Metabolic Imaging
• Mitochondrial Physiology

Background:

• Mitochondrial dysfunction is central to diseases like diabetes and heart disease.
• Current studies often use isolated mitochondria, limiting in vivo relevance.
• Non-invasive methods are needed to study mitochondrial function in living organisms.

Purpose of the Study:

• To develop a novel method for high-resolution dynamic ³¹P-MR spectroscopic imaging (MRSI).
• To enable non-invasive, dynamic metabolic mapping in rodent models.
• To assess mitochondrial function in vivo.

Main Methods:

• Integrated physics-based spectral models, biochemical modeling, and subspace learning.
• Employed rapid spiral trajectories and sparse sampling for fast data acquisition.
• Utilized a low-rank tensor-based framework for image reconstruction.

Main Results:

• Achieved high-resolution dynamic metabolic mapping in rat hindlimb (4x2 mm³, 1.28 s).
• Enabled in vivo mapping of phosphocreatine resynthesis time-constant, an index of mitochondrial oxidative capacity.
• Demonstrated reproducibility and validated accuracy through in vivo and in vitro experiments.

Conclusions:

• A novel model-based method for high-resolution dynamic ³¹P-MRSI was developed.
• The method effectively delineated metabolic heterogeneity in rat hindlimb.
• This technique offers potential for in vivo, longitudinal studies of mitochondrial dysfunction in disease.