Multi-Echo Spin-Echo (MESE) Signal Behavior of Paramagnetic Holmium-166 Loaded Microspheres for Radiotherapy: Experiment and Simulation

Gerrit Hendrik van de Maat¹, Peter R. Seevinck¹, Koen L. Vincken¹, Hendrik de Leeuw¹, Chris J. Bakker^1,2

The potential of multi-echo spin-echo (MESE) measurements for quantification of holmium-166 loaded microspheres (HoMS) was explored. This was done by investigating the signal decay due to HoMS by MR experiments on a gel series containing HoMS and by Monte Carlo simulations. Results were compared to the theoretical model of strong field behavior and appeared to be in good agreement for a wide range of HoMS concentrations. The study indicates the potential of MESE for the quantification of HoMS concentrations up to 20mg/ml.