A R2/R1 ratiometric procedure for a concentration-independent, pH-responsive, Gd(III)-based MRI agent.
A novel procedure for making the pH responsiveness of a Gd-based probe independent of its concentration has been developed. The method is based on a ratiometric approach and requires the measurement, at magnetic fields higher than 1 T, of the paramagnetic contribution to the longitudinal and the transverse NMR relaxation rates of water protons in the presence of a Gd-based probe with a rotational mobility in the nanosecond time scale. The method has been tested and validated in vitro by using a macromolecular adduct based on the polyornithine backbone, whose rotational mobility is pH dependent. The results reported in this communication improve substantially the diagnostic potential of MRI responsive agents.
Aime
Silvio
S
Dipartimento di Chimica IFM and Molecular Imaging Center, Via Pietro Giuria 7, I-10125 Torino, Italy. silvio.aime@unito.it
Fedeli
Franco
F
Sanino
Alberto
A
Terreno
Enzo
E