[Magneto-pharmaceutic contrast changes in nuclear magnetic resonance tomography].

Changes in contrast due to paramagnetic substances depend on many factors, such as the properties and concentration of the substance, the external pulse and time parameters and the inherent relaxation time of the tissues. The physical background for contrast enhancement by paramagnetic substances is reviewed and the various groups of magneto-pharmaceuticals which have been used experimentally and clinically are described. The effect on signal intensity due to changes in dose, pulse sequence, repetition and echo times have been simulated and measured on phantoms and the effect of various tissue relaxation times on contrast has been investigated.