1. A method for operating a magnetic resonance tomography apparatus having a gradient system and a radio-frequency system which, in combination, provide location coding for magnetic resonance signals from an examination subject, said method comprising the steps: placing a region to be imaged in an examination subject in an imaging volume of said magnetic resonance tomography apparatus; obtaining image datasets of at least portions of said region in a time sequence; determining a positional change of at least a part of said region with respect to said imaging volume by comparing a first of said image datasets to a second of said image datasets, said first and second image datasets being generated in chronological succession; and adapting said location coding to said positional change for at least one of said image datasets which is obtained in time following said first and second image datasets.