Table 1 A comparison of the relative advantages and disadvantages of imaging metabolism with hyperpolarized ¹³C- and ²H-labelled substrates.

Complex equipment required for hyperpolarization.

Material can be taken off the shelf

Administered intravenously

Can be administered orally

Can be implemented at clinical magnetic field strengths (e.g., 3 T)

Although can be used clinically at 3 T⁵¹, the narrow frequency range and broad resonances means that it works better at higher field strengths, where spectral resolution improves linearly with field and sensitivity improves with the magnetic field to a power of + 1.65⁵².

Short polarization lifetimes make it logistically more challenging to administer a hyperpolarized ¹³C-labelled substrate in the clinic.

The material is stable and therefore quality control is not required immediately prior to administration.

Polarization is short-lived and therefore the technique can only interrogate relatively rapid metabolic reactions.

The ²H label is stable and therefore in principle can be used to interrogate slower metabolic reactions.

The high sensitivity of detection means that relatively low concentrations can be used, avoiding potential toxicity problems.

The low sensitivity of detection requires relatively high concentrations of the labelled material to be administered, which clinically may restrict use to substrates with a very low toxicity profile.

Detection of the ¹³C label requires the scanner to have X nucleus capability.

The ²H label can be detected indirectly via the loss of ¹H signal intensity⁵³.