Abstract: A method of producing a magnetic resonance image of a defined region of an object by an echo volumar imaging process including subjecting the object to an initial selection process to select a thick slice within the object to produce an active volume of spin magnetisation subjecting the active volume so defined to a combination of 180.degree. RF pulses and suitably modulated x, y and z gradients to produce an echo volumar image.

Abstract: A magnetic resonant image of an object is produced by subjecting the object to an initial slice selection to provide an active region and by subjecting the active region to a plurality of 180.degree. RF pulses and appropriate amplitude modulated x and y gradients.

Abstract: A coil circuit comprising a multi-mode resonant gradient or RF coil circuits for imaging and spectroscopy in Nuclear Magnetic Resonance systems.

Abstract: A resonant array for NMR for use at high frequencies, the array comprising two identical end structures and a plurality of continuous rods joining the identical end structures to comprise a plurality of or electrical circuit sections, the continuous rods being of electrically conductive material; the continuous rods thereby supporting the end structures a predetermined distance apart.

Abstract: Zonal magnification of a selected area of an image produced by Echo Planar Imaging is acheived by taking images of a defined area in the presence of a selective 180.degree. R.F. control pulse so that subsequent processing produces a magnified image of the selected area with enhanced resolution.

Abstract: A nuclear magnetic resonance (NMR) method of producing a series of three or four dimensional spin parameter maps of a defined region, which spin parameter maps are displayable as a set of contiguous planar spin parameter maps with arbitrary orientation.

Abstract: A surface electrical coil structure for use as a signal receiver and/or transmitter with the desired magnetic field characteristics and which comprises a plurality of small coils positioned over or around a specified volume each coil being singly or severally electrically connected such that the flow of electrical current within each coil produces the desired signal response or magnetic field.

Abstract: The screen is provided by surrounding the coil producing the magnetic field with a set of electrical conductors the currents within the conductors being controlled in such a manner that the field is neutrailized in a specific region of space, the current distribution within the conductors being determined by calculating the current within a hypothetical superconductive shield which would have the effect of neutrailizing the field, the current through the conductors thereby being a substitute for the superconductive shield.

Abstract: A magnetic coil comprising a plurality of conductors is designed by calculation of the continuous current density required on the surface on which the conductors are positioned to generate a specific magnetic field on a further target surface or at specified points.

Abstract: A magnetic field of required strength is provided in a desired space by a set of electrical conductors supplied with an electrical current or currents the current distribution being determined by the induced surface current distribution in a conductive former shaped to be of the same shape as the set of conductors. This enables magnetic coils of complex design to be readily designed.

Abstract: A switched coil arrangement is connected in a bridge configuration of four switches S.sub.1, S.sub.2, S.sub.3 and S.sub.4 which are each shunted by diodes D.sub.1, D.sub.2, D.sub.3 and D.sub.4 so that current can flow in either direction through a coil L depending on the setting of the switches. A capacitor C is connected across the bridge through a switch S.sub.5 to receive the inductive energy stored in coil L on breaking the current flow path through the coil. The electrostatic energy stored in capacitor C can then be used to supply current through the coil in the reverse direction either immediately or after a time delay. Coil L may be a superconductive coil. Losses in the circuit can be made up by a trickle charge of capacitor C from a separate supply V.sub.2.

Abstract: A method of investigating a body by nuclear magnetic resonance comprising preferentially exciting resonance in a slice of the body, applying a magnetic field to the body having first and second gradients (Gx, Gy) in different directions in the slice with both the gradients being periodically reversed at regular intervals, detecting the free induction decay signals occurring when the gradients are applied and processing the detected signals to retrieve data. The method is an adaptation of the echo-planar technique suitable for obtaining chemical shift information.

Abstract: This invention provides methods of investigating a body by nuclear magnetic resonance. Nuclear magnetic resonance is preferentially excited in a slice of the body and the resulting free induction decay signals are detected in the presence of a magnetic field having first and second gradients (G.sub.y, G.sub.x).In one proposed method two experiments are performed in which the phase of the first gradient (G.sub.y) reversal is opposite, and the detected signals from the two experiments are edited to obtain a set of signals, for Fourier transformation, occurring when the first gradient has one sense. Two such sets may be obtained, one for each sense of the first gradient, and the data obtained after Fourier transformation re-ordered and added.In a second proposed method the second gradient (G.sub.x) is applied only when the first gradient (G.sub.

Abstract: Spin density distribution in a sample subjected to a static magnetic field along a y-axis is determined by subjecting the sample to an initial magnetic field gradient Gz to the static field together with a 90.degree. selective rf pulse to select a strip. The Gz gradient is then replaced by a filter gradient Gx for a limited period of time during which the free induction signal only partially decays and then immediately replacing the filter gradient by a read gradient Gy and then reading out the free induction decay signal. The sequence may be repeated cyclically with a delay between each cycle. (FIG. 4).

Abstract: A display device has its input information subject to a non-linear processing in order to compensate for the non-linearity of a sensor or in order to enhance the display. The input is periodically read and after processing is converted to a time signal by means of a down counter fed with clock pulses. The time signal is used to control the dwell time of a beam of an oscilloscope or the pen lift mechanism of a chart recorder.

Abstract: The nuclear magnetic resonance spin density distribution in a sample is obtained by subjecting the sample to a static magnetic field and exciting the sample with a selective or non-selective r.f. excitation pulse and a combination of magnetic field gradients which vary in directions along and orthogonal to the direction of the static field. One or more of the gradients are repetitively reversed to allow cyclic regrowth and decay of the free induction decay signal.

Abstract: A nuclear magnetic resonance spin density distribution in a sample is obtained for a selected plane or planes by placing the sample in a static magnetic field, applying a gradient to the field and simultaneously applying selective rf pulses to select a plane or planes in the sample, switching to an orthogonal gradient and simultaneously applying selective rf pulses to select strips in the selected plane or planes and then applying orthogonal field gradients to the sample of such relative magnitudes that each point of the selected strips is subjected to a resultant magnetic field of amplitude unique to that point. The free induction decay signal is then read out from the strips.

Abstract: Nuclear magnetic resonance apparatus designed to enable two and three dimensional images of objects to be obtained has coils for applying a static magnetic field and for applying magnetic gradients to the field in each of three orthogonal directions over the entire volume of a sample and a radio frequency signal generator for applying signals having selected frequency components simultaneously with the magnetic field gradients. In use the spins in all regions of a sample except a slice are saturated or excited in the presence of one magnetic field gradient then a slot in the slice is energized in the presence of a second magnetic field gradient and the free induction decay from the slot read out in the presence of a third gradient. The procedure is repeated for successive slots in a slice and for successive slices.