LANTHANIDE-EDTA DOPED AGAROSE GELS FOR USE IN NMR IMAGING PHANTOMS

Gadolinium-ethylene-diamine-tetraacetic acid (Gd-EDTA) doped agarose g els have been used extensively to produce magnetic resonance imaging t est materials, These materials are limited in their use in imagers ope rating at different frequencies and temperatures, The aim of this pape r is to show that the theories used to predict the relaxation times fo r Gd-EDTA doped gels could be used for other paramagnetic lanthanide-E DTA gels with the aim of producing materials whose relaxation times ca n be theoretically determined but are less temperature and frequency d ependent, In the present work, various lanthanide-EDTA gels were studi ed regarding their NMR T-1 and T-2 water proton relaxation time depend encies with temperature and proton Larmor frequency. Gd-EDTA doped aga rose gels have a T-1 relaxation time dependence with temperature of 7. 5 ms/K, However an Er-EDTA doped gel has a temperature dependence of o nly 3.2 ms/K. Similarly Gd-EDTA doped agarose gels vary by 3.48 ms/MHz over the frequency range 2.5 MHz to 80 MHz compared to Bo-EDTA, which varies 0.359 ms/MHz over the same range. These results show that it i s possible to produce lanthanide-EDTA doped agarose gels that have mar kedly reduced temperature and frequency dependences of their relaxatio n times, but are still predictable using existing theories, This would allow the direct comparison of the performance of imagers operating a t different frequencies and temperatures. (C) 1997 Elsevier Science In c.