James A. Rioux1, 2, Chris V. Bowen2, 3, Valerij G. Kiselev4
1Department of Physics, Dalhousie University, Halifax, Nova Scotia, Canada; 2Institute for Biodiagnostics (Atlantic), National Research Council, Halifax, Nova Scotia, Canada; 3Departments of Physics, Radiology and Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; 4Department of Radiology and Medical Physics, University Medical Center Freiburg, Freiburg, Germany
Existing analytical models of the MRI signal response to spherical magnetic particles (including SPIO-labelled cells) describe the FID and the signal at the echo time TE of spin echo sequences. In this work, we present an extension of these models that also describes the complete signal evolution during the spin echo in regimes where diffusion cannot be neglected. This model shows good agreement with both experimental data and Monte Carlo simulations. Fitting experimental data to this model may allow extraction of additional physical parameters, providing improved quantification of labelled cells.