I'll spend time on this if I can, but for the moment just imagine that in frequency space, where MRI acquisition occurs, all I need to do to blank out an imaging anomaly is discard spatial frequencies that correspond to the principal spatial frequencies of the anomaly. This is analogous to blurring your speech by notch filtering the principal frequencies of your voice. With appropriate filtering, I can make your voice nearly indistinct from background noise, so that it appears not be there.
