Bias Field Correction in Magnetic Resonance Images of a Rat Brain

Magnetic Resonance Imaging (MRI) is nowadays a widely used medical tool, as it is a non-invasive and non-harmful way to study inner soft tissues. One of the characteristics of this method is the bias field, also called Intensity In-homogeneity (IIH), which is an artifact that affects quantitative image analysis consisting in a low frequency variation of the brightness through all the image acquired. This undesired effect makes difficult medical functions such as visual inspection or also intensity-based segmentation [1]. The bias field is a deterministic function tied to complex physical interactions between the magnetic and electric fields and the living tissues, and this is why in this paper this bias field is directly corrected from the corrupt image data, using all the a priori information at our disposal. We will speciffically work on surface-coil images acquired at 9.4T, where the inhomogeneity effect is even stronger [2].