Paramagnetic relaxation-based 19F MRI probe to detect protease activity

A novel design principle for F-19 MRI probes detecting protease activity was developed. This principle is based on F-19 MRI signal quenching by the intramolecular paramagnetic effect from Gd3+. The intramolecular Gd3+ dramatically attenuated the F-19 probe signal, and the paramagnetic effect was cancelled by the probe hydrolyzation by caspase-3. Using this probe, it was shown that the probe could detect caspase-3 activity spatially from a phantom image using F-19 MRI.