Zinc-sensitive MRI contrast agents: importance of local probe accumulation in zinc-rich tissues.

We present the in vitro characterisation of a Gd 3+ -based contrast agent that responds to Zn 2+ upon interaction with Human Serum Albumin. We show that the contradictory in vivo behaviour is related to Gd 3+ -accumulation in Zn-rich tissues. This highlights the importance of the biodistribution of such contrast agents.