Phase-Encoded Hyperpolarized Nanodiamond for Magnetic Resonance Imaging

TL;DR

This paper introduces a novel MRI imaging technique using hyperpolarized nanodiamonds with phase-encoded contrast, enabling detailed, label-specific imaging of biological structures based on spin orientation.

Contribution

It demonstrates the use of nanodiamond's intrinsic paramagnetic centers for hyperpolarized 13C MRI with phase-contrast, a new modality for bio-imaging.

Findings

Nanodiamonds exhibit hours-long T1 relaxation times.

Phase-encoded hyperpolarization enables spin-based tagging.

Spatial resolution of millimeter-scale structures achieved.

Abstract

Surface-functionalized nanomaterials can act as theranostic agents that detect disease and track biological processes using hyperpolarized magnetic resonance imaging (MRI). Candidate materials are sparse however, requiring spinful nuclei with long spin-lattice relaxation (T1) and spin-dephasing times (T2), together with a reservoir of electrons to impart hyperpolarization. Here, we demonstrate the versatility of the nanodiamond material system for hyperpolarized 13C MRI, making use of its intrinsic paramagnetic defect centers, hours-long nuclear T1 times, and T2 times suitable for spatially resolving millimeter-scale structures. Combining these properties, we enable a new imaging modality that exploits the phase-contrast between spins encoded with a hyperpolarization that is aligned, or anti-aligned with the external magnetic field. The use of phase-encoded hyperpolarization allows nanodiamonds to be tagged and distinguished in an MRI based on their spin-orientation alone, and could permit the action of specific bio-functionalized complexes to be directly compared and imaged.