Mutual-information based optimal experimental design for hyperpolarized [Formula: see text]C-pyruvate MRI

Area of Science:

• Medical Imaging
• Biophysics
• Metabolic Imaging

Background:

• Hyperpolarized MRI (HP-MRI) is crucial for measuring tumor metabolism.
• Accurate quantification of the pyruvate-to-lactate exchange rate is essential for assessing metabolic activity.
• Experimental design significantly impacts the precision of recovered kinetic parameters.

Purpose of the Study:

• To develop an information-theory-based optimal experimental design for HP-MRI.
• To minimize uncertainty in the apparent pyruvate-to-lactate exchange rate ([Formula: see text]).
• To optimize pulse sequence flip angles for enhanced metabolic measurements.

Main Methods:

• Utilized mutual information to quantify information content regarding pyruvate conversion kinetics.
• Employed an optimization approach to determine optimal flip angles for HP-MRI pulse sequences.
• Compared time-varying flip angle schemes against constant flip angle schemes.

Main Results:

• Mutual information analysis guided the optimization of flip angles.
• Both variable and constant flip angle schemes achieved comparable accuracy and precision.
• Optimized constant flip angles of 35° for pyruvate and 28° for lactate were identified.

Conclusions:

• An information-theory approach effectively optimizes experimental design in HP-MRI.
• Recommended optimized constant flip angles (35° pyruvate, 28° lactate) offer a practical balance of performance and implementation ease.
• This method enhances the quantitative accuracy of tumor metabolism assessment using HP-MRI.