B0 Distortion
When collecting multiple modes of MRI images it is often assumed that all images are exactly the same and overlap perfectly when the images are aligned. In fact, comparing MRI images is similar to looking at a house of mirrors at a carnival - each one is distorted differently.
Inhomogeneities in the B0 magnetic field are manifested as distortions in an image, and are most noticeable near air/tissue interfaces.
Echo planar imaging (EPI) sequences are most susceptible due to the limited bandwidth of information per pixel. As a result, diffusion weighted sequences, functional MRI and resting state fMRI scans exhibit noticeable geometric distortions as compared with T1 and T2 images.
By incorporating a fieldmap, one is able to model these distortions and correct these images so that all images are more perfectly aligned.
I am interested in developing improved B0 distortion corrections in order to improve multimodal image analysis.