With the advent of integrated whole-body scanners allowing for simultaneous recording of PET and MRI data, the interest in dual-mode contrast agents (CA) awakened, for two reasons: Targeted bimodal PET/MRI probes would release the full synergy between high sensitivity of PET and high resolution of MRI. Furthermore, application of responsive MRI-CA (whose relaxivity is determined by tissue pH, serum metal ions, enzyme activity etc.) seem to be of special interest.
However, such probes require quantification of their in vivo concentration; for PETlabelled smart MRI probes, these data could be taken from simultaneously recorded PET. We Aimed at labelling of gadolinium-CA with 68Ga because this nuclide is widely available at low cost.