NMR RELAXATION STUDIES WITH MNDPDP

Purpose: Our studies were designed to compare the efficacy of mangafod ipir trisodium (MnDPDP, Teslascan) as a tissue-specific MR agent with that of manganese chloride (MnCl2), to compare the efficacy of differe nt doses and rates of administration of MnDPDP, and to collect the dat a needed for predicting optimum pulse sequences. Material and Methods: The dose response for the relaxation rates R1 and R2 at 0.47 T, and t he manganese (Mn) concentrations in rat liver and in the liver, pancre as, heart and adrenals of pigs was determined for both MnDPDP and MnCl 2 administered i.v. Computer simulations were carried out to model the effects of different tissue Mn concentrations and TR on signal intens ities and contrast-to-noise ratios. Results: In rat liver and pig orga ns both compounds produced a positive dose-response in R1 and tissue M n concentration, and only small or no response in R2. The Mn concentra tion in rat liver was positively correlated with R1, regardless of the form in which Mn was given, or the rate of administration. Optimal im aging parameters are therefore expected to be different pre- and post- MnDPDP administration. Conclusion: The added cardiovascular safety of MnDPDP compared with MnCl2 does not result in loss of efficacy in incr easing R1 at the intended clinical dose of 5 mu mol/kg, MnDPDP. The ch anges in R2 were too small to affect T2-weighted images. The data give the basis for choosing the appropriate pulse sequences for MnDPDP-enh anced MR imaging.