This five slides about chemical exchange transfer (CEST) discusses the magnetic properties of paramagnetic metal ions and their use as MR imaging agents. This includes tranditional contrast agents that affect the relaxation rate of nearby water protons and paramagnetic shift reagents suitable for CEST imaging applications. A recent redox-active cobalt complex is presented as an innovative agent for mapping redox imbalances in vivo.
Note: slides 2 and 3 are hidden. These slides present the basis of MR signal (slide 2) and relaxation mechanisms pertinent to T1 and T2 contrast agents (slide 3). This information is relevant to CEST agents since kex must be equal to or less than the frequency difference between the exhangeable protons and bulk water. Increasing the frequency difference between these two signals permits faster exchange, which may then outcompete T1 and T2 relaxation mechanisms.
Following presentation of these five slides, students will be able to:
- Discuss MR signal origin and why Gd(III)-based agents improve image contrast.
- Identify magnetic properties relevant to relaxation and shift agents.
- Rationalize the CEST phenomenon and why paramagnetic transition metals are suitable for developing CEST agents.
This LO was developed at the 2014 VIPEr Workshop: Bioinorganic Applications of Coordination Chemistry, and therefore has yet to be implemented in a classroom setting.