Upconversion and Magnetic Resonance Imaging

In an early study we showed the potential of Gd -based nanoparticles for magnetic resonance (MRI) and computed tomography (CT) [121]. In this article we speculated that Gd ions not at the surface could be in part responsible for the high relaxivities. The ri (ri = 1/Ti) and r2 ( 2= I/T2) values of the citrate Gdp3 nanoparticles at 3.0 T gave mass relaxivities of 8.8 0.2 and 9.4 0.2 (mg ml ) s . However, a later systematic study by us with sub-lOnm NaGdp4 [122] proved this wrong. For the latter the respective 

Work on Ln203 nanoparticles by Peters et al. has also appeared [126,127] with an excellent recent review on and Ho -based MRl contrast agents [128]. 

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