Abstract: In a nuclear magnetic resonance apparatus and RF coil arrangement comprises two or more separable parts (51 and 53) adapted to be assembled around the body to be examined to form the coil arrangement. The parts are suitably arranged to be connected, when assembled, by adjustable coupling structure (55, 57, 59 and 61) so that the volume embraced by the coil arrangement may be adjusted. The invention enables the coil arrangement to be positioned more closely around a body being examined than is possible with conventional, unitary, tubular coil arrangements.

Abstract: A radio frequency coil arrangement for an NMR imaging apparatus comprising one or more coils (10A, 10B) which are convexly shaped to facilitate close fitting of the arrangement round a body being imaged.

Abstract: A method and apparatus for NMR imaging a selected elongated region of a body wherein different portions of the elongated region respectively defined by the intersection of a number of discrete first slices perpendicular to the region with a second slice containing the whole region are imaged in turn. Each portion is imaged by exciting spins in one of the first slices (B1 (90), G1z, -G1z) and then rotating through 180.degree. any spins in the second slice (B2 (90), B3 (90), -Gy, Gy) the resulting spin echo of spins in the region of intersection of the first and second slices being then suitably encoded (Gx, G2z) and detected. The method and apparatus find particular application for imaging and spine of a patient.

Abstract: An NMR apparatus capable of being used for both chemical analysis and imaging of a body without adjustment of the magnetic field strength of the magnet system used to define the equilibrium axis of magnetic alignment of the nuclei within the body. The apparatus incorporates two magnet systems each capable of independently defining an equilibrium axis of magnetic alignment for nuclei within a body to be examined by NMR techniques.

Abstract: An NMR imaging method and apparatus wherein spatial encoding of spins is effected by applying a radio frequency field (B2) having a gradient, thereby avoiding the eddy current problems which can arise with d.c. gradient magnetic pulses conventionally used for spatially encoding spins.

Abstract: In a method of imaging a body in which nuclear magnetic resonance is excited in a region including part of the body, and the free induction decay signal is measured, a quantity of a material of known nuclear magnetic resonance properties is included in the region so as to enhance the measured free induction decay signal. This then reduces the generation of noise during subsequent processing of the signal. The material is suitably water in a container.

Abstract: A magnetic shim for an N.M.R. apparatus comprises a deformable body (particularly a flexible sheet) of electrically insulating material (e.g. P.V.C.) within which magnetic material (e.g. .gamma.-ferric oxide or barium ferrite) is dispersed. The shim may easily be attached (e.g. by an adhesive backing layer) to an inside wall of the apparatus and may suitably be cut to size until suitable magnetic compensation is achieved by trial and error. The nature of the compensation effected by the shim may be altered by employing different magnetic materials dispersed within the non-conducting material and/or by varying their concentration.

Abstract: A method and apparatus for determining the rate and direction of flow of a liquid in a selected region of a body by NMR techniques. NMR is excited preferentially in a slice of the body which includes the region and then a magnetic field having a gradient in a direction parallel to the flow of the liquid is applied, this field being effective to cause a phase difference between the resonance for the liquid which is flowing, or has flowed, in the region and the resonance for the rest of the slice. The free induction decay signal is measured, and the phase difference between the signal from the liquid, and the signal from the rest of the slice is related to the rate of flow of the liquid through the region.

Abstract: In a method of investigating the distribution of a quantity in a chosen region of a body (E) by nuclear magnetic resonance techniques movement of the body during the investigation is monitored by probes (A, B C) attached to the body and responsive to magnetic fields applied to the body during the investigation. An apparatus for carrying out the method is also described.

Abstract: A coil arrangement for use in generating and detecting nuclear magnetic resonance (NMR) in a body, e.g. an NMR imaging apparatus, which comprises a conductor arrangement which can be used both as an RF field generating coil and an orthogonally polarized RF field detecting coil. The arrangement comprises a plurality of non-magnetic electrically conductive paths (34 to 50) extending generally parallel to the axis of a cylindrical volume, and means (51, 53) interconnecting the paths at each of their ends. An input signal applied to diametrically opposite paths (36 and 46) causes currents to flow in loops formed by the paths and interconnections so as to produce a field directed perpendicular to the axis of the volume, and an output for application to a detector is derived from diametrically opposite paths (31 and 41) which are orthogonal to the paths to which the input signal is applied so that zero current is induced in them by the field produced by the input signal.

Abstract: A coil arrangement for generating a high frequency magnetic field in a generally cylindrical volume, e.g. for use in an NMR imaging apparatus, comprises a plurality of conductors (11, 13, 15, 17, 19) extending generally parallel to the axis of the volume at spaced positions around the volume and connection means (25, 27, 29) whereby the conductors are connected in electrically parallel paths for energization from a common source (S). The paths are arranged to have a high self-resonant frequency compared with the frequency of the source, e.g. by being arranged each to comprise a single turn only, and the impedances of the paths are arranged to differ so that when energized the fields produced by the individual conductors combine to produce a resultant desired field distribution.

Abstract: A method and apparatus for determining the rate of flow of a liquid in a region of a body using a nuclear magnetic resonance technique. Nuclear magnetic resonance is excited firstly preferentially in a slice of the body which includes the region and then over the whole of the body. A period of time is allowed to elapse, and nuclear magnetic resonance is then excited preferentially in the slice. The free induction decay signal is then measured, and the signal is related to the state of flow of the liquid through the slice.

Abstract: A method of exciting nuclear magnetic resonance at a particular location of a body comprises: exciting first nuclear spins in the body (A, Gx, -G'x, B, Gxd, C, Gy, -G'y, D) so that spins occurring in a first selected region of the body have their spin vectors lying in a first direction and any spins occurring elsewhere in the body have their spin vectors lying in a plane normal to the first direction; dephasing the spins in the body whose vectors lie in said plane (Gyd); and exciting nuclear spins in a second selected region of the body (E, Gz, -G'z) which intersects said first region at said particular location so that the vectors of the resultant spins in said particular location only are aligned in said plane.The method finds particular application in providing data for chemical analysis of material at a particular location of a body.Apparatus for carrying out the method is also described.

Abstract: A multi-slice method of NMR imaging wherein a number of discrete slices S.sub.1, S.sub.2, S.sub.3, S.sub.4 are excited simultaneously by using the usual field gradient Gz but an r.f. pulse B.sub.1 which is a mix of a number of pulses of different discrete frequencies, f.sub.1, f.sub.2, f.sub.3, f.sub.4, and recovering data in the presence of an alternating gradient G.sub.2 z in the same direction as used to establish the slices such that discrete spin echo signals of different frequency occur for each slice. Apparatus for use in the method is also disclosed.

Abstract: A magnet pole piece for an NMR imaging magnet is made of a plurality of magnetic wires (3) with one end of each wire held in a non-magnetic spacer (1), the other ends of the wires being brought to a pinch (5), and connected to a magnetic core (6). The wires are embedded in a synthetic resin (4) and the magnetization and uniformity thereof can be varied by adjusting the density of the wires at the spacer which forms the pole piece.

Abstract: A method and apparatus for determining the spatial distribution of the chemical shift spectra of a chosen element across a region of a body. Where the region is a slice, nuclear magnetic resonance for the element is excited preferentially in the slice. First and second pulsed magnetic gradient fields (Gx, Gy) having magnetic field gradients in first and second mutually orthogonal directions in the plane of the slice are applied. The value of the gradient of the first field is stepped through a range of first values, for each of the first values the gradient of the second field being stepped through a range of second values.

Abstract: A nuclear magnetic resonance imaging apparatus for medical use wherein a patient to be examined is positioned on support means (1) in a sitting posture and the required magnets (7, 11) and RF coils (13, 15) are arranged so as to allow easy movement of the patient into and out of the apparatus.

Abstract: A signal generator for generating signals to control a plurality of devices includes a digital computer and a control interface apparatus. The plurality of devices to be controlled is connected in use to the control interface apparatus. The computer has peripheral device select lines, output control lines, and a data output bus. The control interface apparatus is connected to one of the peripheral device select lines, and while it is enabled by that select line it decodes a device address on the data output bus under the control of one of the output control lines so as to select one of the plurality of devices connected to the interface apparatus, the number of the plurality of devices connected to the interface apparatus thus being limited only by the capacity of the data output bus.

Abstract: Method and apparatus for producing an N.M.R. picture of a plane through an object by isolating the plane using an oscillating gradient and interrogating the plane using a rotating gradient and a multiplicity of R.F. pulses which are averaged over a defined period to produce an average response which is used to produce the N.M.R. picture.

Abstract: A method of imaging a body by nuclear magnetic resonance wherein volume scanning of a region of the body is achieved by scanning a first planar slice of the region and at least one further slice of the region in the relaxation time for the scan of the first slice.