Towards iron oxide nanoparticles quantization in molecular MR images by default field deconvolution

MRI contrast agents, such as USPIO, are often used for pathology diagnoses. Locating and quantifying USPIO is of high interest. Contrast techniques like T₂ ^* cartography and positive contrast imaging have been developped in recent years. Another strategy is to analyse magnetic field inhomogeneities produced by the particles. We present a 3D post-processing method SYMDEF. This method consists in obtaining a SusceptibilitY Map by the deconvolution of DEfault Field map (the magnetic susceptibility is linked to USPIO concentration). Constrained least squares filtering is proposed to add robustness to SYMDEF. SYMDEF is compared with another method detailed by Haacke. Results show that SYMDEF allows us to retrieve susceptibility information from default field map without any prior knowledge as susceptibility. Our approach is a good candidate for USPIO quantization.