Quantitative Analysis of Transverse Relaxation Due to Strongly Magnetized Micron-Sized Spheres Subjected to Unrestricted Diffusion in Gradient Echo and Spin Echo Imaging: Validation of Theory with Experiments and Monte Carlo Simulation

Peter Roland Seevinck¹, Koen Lucas Vincken¹, Gerrit Hendrik van de Maat¹, Chris J.G. Bakker¹

The signal decay time course of FID and SE of an aqueous suspension of strongly magnetized micron-sized spheres was investigated in great detail to explore the influence of volume fraction, field strength and diffusion. Excellent agreement between MR experiments, Monte Carlo simulations and both the theory of the static dephasing regime and the strong field behavior was demonstrated based on R2, R2 and R2* relaxation rates. This allows accurate prediction FID and SE signal behavior and quantification strongly magnetized spherical particles such as holmium- and iron-loaded microspheres and iron-labeled cells.