Chapter 14: Fast Multi-dimensional NMR for In Vivo Spectroscopy

Molecular imaging techniques based on hyperpolarisation-enhanced magnetic resonance (HP-MR) are revolutionising disease diagnoses. By measuring the chemical kinetics and pool sizes of specific biochemical compounds in vivo, these have the potential to detect small, yet significant differences between healthy and pathological cell metabolism in the imaging subject. In this chapter, fast-imaging strategies for spectral and spatially resolved HP-MR are reviewed. Presently there exist pulse sequences that can probe up to five spatiotemporal or frequency dimensions in vivo and can be tailored to the HP substrate and products to be measured, their SNR and resolution needed. We organize this review by discussing the current state of in vivo MR, including in vivo MR of hyperpolarised proton and carbon-13, as well as deuterium and nitrogen-15. Then, we discuss acquisition strategies for HP-MR in vivo and their limitations, including hardware and software capabilities of NMR spectroscopy/MRI detection systems, and other additional challenges of data sampling in living biological systems.