Hyperpolarisation criteria in magnetic resonance

Area of Science:

• * Physics
• * Chemistry
• * Biophysics

Background:

• * Nuclear Magnetic Resonance (NMR) spectroscopy suffers from low sensitivity due to limited equilibrium magnetization.
• * Hyperpolarisation techniques are crucial for overcoming sensitivity limitations in NMR.
• * The precise definition and interpretation of
• hyperpolarisation
• within the magnetic resonance community require clarification.

Purpose of the Study:

• * To evaluate the consistency of a formal, entropy-based definition of hyperpolarisation with its practical application in magnetic resonance.
• * To introduce and validate an alternative hyperpolarisation criterion based on latent polarisation.
• * To establish a more practical and widely applicable definition of hyperpolarisation.

Main Methods:

• * Analysis of the formal definition of hyperpolarisation using von Neumann entropy.
• * Introduction of the concept of latent polarisation as a measure of extractable polarisation.
• * Comparison of the entropy-based criterion with the latent polarisation criterion against common usage in magnetic resonance.

Main Results:

• * The formal entropy-based definition of hyperpolarisation does not always align with the common understanding of achieving larger NMR signals.
• * Latent polarisation, representing the maximum extractable polarisation, provides a criterion that correlates better with general usage.
• * The study highlights that multiple valid interpretations of hyperpolarisation exist, depending on the specific research context.

Conclusions:

• * The formal definition of hyperpolarisation based on entropy may not fully capture the practical implications of enhanced NMR signals.
• * A hyperpolarisation criterion based on latent polarisation offers a more practical and consistent measure aligned with community standards.
• * The choice of hyperpolarisation definition should be guided by the specific scientific questions and applications in magnetic resonance research.