  The properties of dephasing and the resulting relaxation of the magnetization
are the basic principle on which all magnetic resonance imaging methods are
based. The signal obtained from the gyrating spins is essentially determined by
the properties of the considered tissue. Especially the susceptibility
differences caused by magnetized materials (for example, deoxygenated blood,
BOLD-effect) or magnetic nanoparticles are becoming more important for
biomedical imaging. In the present work, the influence of such field
inhomogeneities on the NMR-signal is analyzed.
