ABSTRACT
The application of paramagnetic metal ion complexes as MRI
contrast agents has an interesting history. Complexes developed
initially as T1 relaxivity agents contained paramagnetic Fe(III) and Mn(II), followed by studies on Gd(III) complexes [1]. More
recently, complexes of lanthanide ions other than Gd(III) have been
developed asMRI contrast agents that operate by chemical exchange
saturation transfer (CEST) [2-4]. In particular, Eu(III), Tm(III), and
Yb(III) have been extensively used as CEST or paramagnetic CEST
(paraCEST) agents as described in detail in Chapter 11. Why would
one then want to develop transition metal ion paraCEST agents
based on different elements? In this chapter, we show that the
unique coordination chemistry, tunable redox potentials as well
as suitable paramagnetic properties of transition metal ions make
them excellent candidates for the development as paraCEST agents.
