One promising candidate metabolite is [1,4-13 C2]fumarate, which is converted to [1,4-13 C2]malate by the enzyme fumarase in one step of the citric acid cycle. Fumarate transport through the cell membrane is a relatively slow process, and so significant formation of malate is only observed in regions of necrotic cells where fumarate has access to the enzyme. This change in chemical identity can be observed in carbon-13 MRI via CSI (chemical shift imaging), and has been shown to be a sensitive marker of cell necrosis . The technique is currently being assessed for application in clinical trials which opens exciting new possibilities for imaging of cell necrosis and diagnostics of therapeutic response . All in vivo experiments to date have used [1,4-13 C2]fumarate polarized via dDNP (dissolution dynamic nuclear polarization) . There are three significant drawbacks to this technique: (1) it is prohibitively expensive, (2) complex cryogenic equipment is required to reach 1.4 K, and (3) the hyperpolarized material is delivered in batch-mode, with tens of minutes of preparation time required between sample deliveries. PHIP (parahydrogen induced polarization) is an alternative hyperpolarization modality which involves chemical addition of hydrogen gas enriched in the para spin isomer to a substrate molecule . PHIP is approximately 1-2 orders of magnitude less expensive than dDNP, and can produce hyperpolarized products with a much higher duty cycle because it only requires chemical reaction with hydrogen gas. However, the application of this powerful tool to in vivo metabolic studies is hampered by the limited number of metabolites that can be hyperpolarized by means of parahydrogen addition to an unsaturated precursor of the target molecule . Hyperpolarized [1- 13 C]fumarate has ]fumarate. The proton singlet order is then transformed into 13 C magnetization by applying a constant-adiabaticity magnetic field cycle , optimized for the [1-13 C]fumarate J-couplings. The fieldcycling profile is shown in the inset.