Radiopharmacy

An example of the LARAMED team expertise on radiopharmacy are results obtained within the METRICS project (acronym for Multimodal pET/mRi Imaging with Cyclotron produced ^51/52Mn iSotopes), which aims to develop the technology needed to obtain a cyclotron driven production of ^51/52Mn PET radionuclides and to achieve PET/MRI hybrid imaging in combination with paramagnetic Mn(II) compounds.

An overview of the recent activities carried out in order to develop a new class of Mn(II) dithiocarbamates complexes which can potentially be used as magnetic resonance imaging contrast media is given below.

 The Mn(II) complexes were prepared by reacting MnCl2∙4H2O(Mn1) with the PTA or dithiocarbamate ligands.

The[ Mn(II)(L)2] (Mn2,Mn3andMn4) complexes were prepared by adding 5mL Milli-Q water containing MnCl2∙4H2O to two equivalents of the sodium salt of the ligand L and L’ (L=[(CH3CH2)2-N-C(=S)S-], or [(CH3CH2OCH2CH2)2-N-C(=S)S and L’=[C7H12O2-N-C(=S)S-]) under inert conditions.

All complexes were characterised with elemental, ESI(+)MS, infrared (IR) and magneto-metric analysis. The magnetic measurements on the Mn complexes were carried out using a Superconducting Quantum Interference Device (SQUID) magnetometer, operating with a maximum applied field H=50kOe. Both longitudinal (T1) and transverse relaxation times (T2) were measured by appropriate spin-echo sequences.

The longitudinal (r1=1/T1) and transverse (r2=1/T2) relaxation rates were measured at 25°C at two magnetic field strengths: 0.5T and 1.5T (corresponding to 20 MHz and 60 MHz proton Larmor frequency) on a Stelar Spinmaster spectrometer working at adjustable field.

The relaxation times of the solutions containing Gadobenato dimeglumina and the Mn chelates were also measured in the concentration ranges between 0.01 and 5.0 mmol/L with MRI phantom measurements at 1.5 T with a clinical SIEMENS Magnetom Aera of 1.5 T.