Antenna system for the nmr - image representation - or nmr spectroscopy, as well as a method for the operation of such an antenna system

摘要

An antenna system for nuclear magnetic resonance (NMR) imaging or spectroscopy devices which produce a uniform magnetic field in an object under examination includes transmit and receive antenna arrays each comprising a group of loop antennas. A signal generating circuit produces a set of input antenna signals which are applied to the loop antennas of the transmit array which transmits RF signals of a frequency that perturbs the magnetic moment of nuclei in a volume of the object. The receiving antenna array is responsive to NMR signals produced by the relaxation of perturbed nuclei in said volume for producing a set of output antenna that are applied to a signal processing circuit. A control circuit selectively controls the relative phases and amplitudes of at least one set of antenna signals to control the size and location of the region of the volume in which excitation of nuclei occurs, or from which NMR signals are processed. The relative phases and amplitudes can be controlled in such a way that nuclei in only a preselected region of the volume are excited, and that NMR signals from nuclei in only a preselected region of the volume are processed.