Abstract: This invention relates to methods and means for improving the sensitivity and signal-to-noise ratio of spin-echo measurements on samples, which have to remain at their own temperature and which have a non-negligible electrical conductivity. These are applied to noninvasive, localized, in vivo examinations of endogeneous tissue, organs, bones, nerves and circulating blood in the course of medical check-ups as well as for differential diagnostics and for the validation of therapeutic measures. This equipment comprises a system of magnets and an arrangement of transmitting and receiving coils encompassing the test person (patient) preferably completely, but at least the region of exploration. Means for the excitation as well as specialized low temperature equipment for the detection of NMR-signals emanating from a very small subregion are provided.