Protocol for producing hyperpolarized ¹³C-bicarbonate for clinical MRI of extracellular pH in aggressive tumors

Tumor acidosis is one of the hallmarks indicating the initiation and progression of various cancers. Here, we present a protocol for preparing a hyperpolarized (HP) ¹³C-bicarbonate tissue pH MRI imaging contrast agent to detect aggressive tumors. We describe the steps for the formulation and polarization of a precursor molecule ¹³C-glycerol carbonate (¹³C-GLC), the post-dissolution reaction, and converting HP ¹³C-GLC to an injectable HP ¹³C-bicarbonate solution. We then detail procedures for MRI data acquisition to generate tumor pH maps for assessing tumor aggressiveness. For complete details on the use and execution of this protocol, please refer to Mu et al.¹.