Abstract: A nuclear spin tomograph comprises a magnet system with a, preferably, elongated holder (19,20) for a test object arranged in its one axis to slide in the longitudinal direction. The test object is further surrounded by coil systems for generating gradient fields and for irradiating a radio-frequency field. The magnet system is provided with a yoke iron body (10) enclosing a longitudinal opening (11) for receiving the test object, with outer marginal areas of the longitudinal opening (11) accommodating coil sections (12, 12'; 13, 13') which extend in the direction of the longitudinal opening (11), which are bent over at the ends thereof and which close above the opening (11) (FIG. 1).

Abstract: In order to record nuclear magnetic resonance signals in an area of interest of a sample body which is exposed to a constant magnetic field, a measuring head is applied to a surface of the sample body adjacent the area of interest. The measuring head includes an RF transreceiver unit having a helical line disposed within a shield being open at one of its radial end planes. The helical line is free from connections on one end, and the other end is arranged as an uppermost winding which is electrically connected to the shield via a connection arranged in the open radial end plane. The amplitude of an RF current supplied to a transmitter coil which is arranged coaxially to said measuring head is adjusted to generate an image plane of predetermined constant magnetic RF field strength B at a defined distance above the open radial end plane. The RF current is gated to induce pulsed nuclear magnetic resonance transitions for a predetermined kind of nuclei with respect to the strength of the constant magnetic field.

Abstract: The use of longer 180.degree. pulse sequences for the generation of spin echos is made possible according to the invention during NMR tomography using the 2d-Fourier transformation process in that the phase coding gradient between each pair of 180.degree. pulses is switched on in such a manner that the dephasing caused between each pair of 180.degree. pulses by the phase coding gradient is twice as great as the dephasing caused before the beginning of the first 180.degree. pulse by the phase coding gradient. The mirror images which appear otherwise when using the known 180.degree. pulse sequences, e.g. the Carr-Purcell-Gill-Meiboom pulse sequence, are avoided by this measure.

Abstract: In an NMR tomography method, the nuclear spins are caused by a pulse sequence to supply in one pass a number of successive induction signals, whereupon the induction signals corresponding to each other as regards their succession in time are processed by calculation to form a plurality of image signal sets corresponding to a sequence of section images which differ from each other by the intensity of the induction signals varying according to the relaxation time T.sub.1 or T.sub.2.

Abstract: An apparatus produces complete stereoscopic images of a three-dimensional object. It comprises an image transmitter (13) on which are shown one after the other in time two-dimensional images (14) corresponding to sections lying one behind the other in space. In addition, the element (18) is provided which is disposed between the image transmitter (13) and an observer (36), said element being synchronously controlled by the image transmitter (13) and changing the spatial positioning of the image (14) between image transmitter (13) and observer (36). Optical means (31, 32) serve to reduce an image (14) shown on the image transmitter (13) in the plane of the element (18) and to re-enlarge it for analysis. The apparatus is particularly suitable for showing tomographic pictures, i.e. for imaging the inside of a living body.

Abstract: The use of longer 180.degree. pulse sequences for the generation of spin echos is made possible according to the invention during NMR tomography using the 2d-Fourier transformation process in that the phase position and, thus, the sense of rotation of the 180.degree. pulses is reversed after every two pulses. The mirror images which appear otherwise when using the known 180.degree. pulse sequences, e.g. the Carr-Purcell-Gill-Meiboom pulse sequence, are avoided by this measure.

Abstract: For the purpose of limiting NMR spectroscopy to a selected area of a body the said area is prepared by applying first a homogeneous magnetic field passing through the entire body and superimposing thereafter upon the said magnetic field a first magnetic field of identical orientation whose strength varies in a first sense (first field gradient), exciting thereafter all the selected nuclear spins present within the body and in addition, selectively, only the nuclear spins present in a first body plane containing the volume element and extending vertically to the said first field gradient so that the selected nuclear spins contained in this body plane are returned to the direction of the homogeneous magnetic field while the nuclear spins outside this plane receive an orientation differing from the sense of the homogeneous magnetic field.

Abstract: In NMR tomography, the nuclear spins of a selected type present in a selected area of a body are selectively excited by applying first a selection gradient field and exciting thereafter the nuclear spins by a HF signal which initially effects a rotation of the nuclear spins situated in a selected plane by an angle .alpha. of less than 90.degree., then a rotation of all selected nuclear spins by 90.degree. and finally again a rotation of the nuclear spins contained in the selected plane by an angle of 90.degree.-.alpha.. As a result thereof, the nuclear spins contained in the selected area have resumed at the end of this excitation their original orientation determined by a homogeneous magnetic field, while nuclear spins located outside this area lie within a plane extending almost vertically thereto. Thereafter, a measuring gradient field may be switched on without disturbing the orientation of the nuclear spins contained in the selected area.

Abstract: A medical device for electroshock therapy, and more particularly a defibrillator for the treatment of ventricular and auricular fibrillation. Devices of this kind contain a high-voltage generator comprising a transformer with a rectifier connected to its output for charging a shunt capacitor which can be discharged through the patient by means of electrodes connected to it. In order to avoid by simple means the occurrence of dangerous leakage currents and in order to simplify the solving of the problem of high-voltage insulation, the rectifier comprises two branch circuits which are connected to a common transformer winding and which feed the shunt capacitor; furthermore, a high-impedance voltage divider is connected in parallel to the shunt capacitor with its center connected to chassis.