Abstract: A method of nuclear magnetic resonance imaging wherein motion artifacts in the image are reduced by compensating for variations in the coupling between the RF transmitter and/or detector coils (9A, 9B and/or 10A, 10B) and the body (43) being imaged due to movement of the body. Compensation is suitably effected by measuring the position of the body (43) with respect to a datum immediately prior to each excitation of nuclear spins in the body and setting the amplitude of the applied RF excitation pulse B (90.degree.) and the detector sensitivity in dependence on the measured position.

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: A nuclear magnetic resonance imaging method and apparatus using the Hahn spin echo technique wherein dephasing of spins due to selection field gradients (G1x, G2x, G3x) applied during the radio frequency excitation pulses (B1 (90.degree.), B2 (90.degree.), B3 (90.degree.) of the Hahn technique is corrected solely by magnetic field gradients (-G'x, -G2'x) applied before the last radio frequency excitation pulse.

Abstract: A nuclear magnetic resonance method and apparatus for examining a predetermined particular location (55) in a body wherein processed data obtained from four procedures are combined to extract processed data relating to the particular location. Each procedure comprises exciting spins in a region (45) of the body including the location (55) and acquiring and processing data in respect of the excited spins. In a first procedure the excited spins are of the same phase throughout the region (45). In a second procedure the excited spins are of a first phase in a first portion (49) of the region (45) of which portion the predetermined location (55) forms part, and are of the opposite phase in the rest of the region (45). In a third procedure the excited spins are of a first phase in a second portion (53) of the region which intersects the first portion (45) at the predetermined location (55) and are of the opposite phase in the rest of the region (45).

Abstract: An NMR chemical shift imaging method and apparatus wherein a number of experiments are performed with different encoding gradients sufficient to obtain a desired spatial resolution in the image, and each of said number of experiments is repeated for each of a number of different delay times between excitation and the start of data collection sufficient to obtain a desired chemical shift resolution in the image.

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 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 nuclear magnetic resonance imaging of a body in which the spins of a chosen nucleus in a selected slice of the body are rotated through an angle appreciably greater than 90.degree.. Two r.f. pulses, each accompanied by a magnetic field having a gradient in a direction parallel to the equilibrium axis of magnetic alignment of the spins are applied in sequence. Each r.f. pulse is at the Larmor frequency for the nuclei in the slice in the presence of the associated field gradient and each r.f. pulse is effective to rotate the spins by not greater than 90.degree.. The r.f. pulses together are sufficient to rotate the spins through the desired angle, the gradients of the magnetic fields being in opposite directions.

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 nuclear magnetic resonance imaging apparatus associated with heat treatment means (45) and arranged to examine material subjected to heat treatment. The heat treatment means may be automatically controlled in dependence on any output produced by the imaging means, and/or manually controlled by an operator viewing a visual display (33) produced by the imaging means. The heat treatment means may be hyperthermia treatment means for treating diseased tissue of a patient.

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 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 method and apparatus for determining the rate of flow of a liquid in a selected region of a body by nuclear magnetic resonance techniques. The method includes a sequence of applying a first magnetic pulse (B.sub.1 (90.degree.)) effective to excite nuclear magnetic resonance of a chosen nucleus within the liquid preferentially in a slice of the body which includes the selected region. A period of time (t.sub.D) is waited and then a second magnetic pulse (B.sub.1 (90.degree.)) is applied which is effective to excite nuclear magnetic resonance of the nuclei preferentially in the slice, and the free induction decay signal is measured. The whole sequence is repeated for different values of the period of time (t.sub.D). The values of the period of time (t.sub.D) and the corresponding measured signals are then related to the rate of flow of the liquid through the slice.

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.