National Research Development Corporation

Oxford Research Systems Limited

Other

British Technology Group Limited

Roger J Ordidge

Peter Mansfield

David N Guilfoyle

Ronald J Coxon

Robert E Gordon

Alistair Howseman

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.

Echo planar imaging using 180 degrees pulses

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.

Echo planar imaging systems

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.

NMR imaging

Enhanced NMR images of a desired portion of an object are obtained by obtaining a plurality of NMR responses of the object each response comprising information from a plurality of smaller volumes within the object and by combining together the plurality of NMR responses by addition or subtraction to obtain enhanced images from the selected smaller volumes.

NMR imaging systems

Undesired signals are eliminated using a shaped RF pulse comprising a region of random frequency components and a region of zero components to effectively eliminate signals from areas volumes or frequency bands which are not required.

NMR spectroscopy and NMR imaging

A method of obtaining an NMR spectrum from a first region lying wholly within a second region of a sample material, comprises obtaining a signal indicative of a first NMR spectrum from substantially all of the second region of the sample material applying to the sample a magnetic field gradient, and simultaneously applying to the sample an Rf perturbing pulse having an amplitude and a frequency distribution such as to perturb nuclear spins in the said first region, but not outside it, removing the magnetic field gradient, and thereafter obtaining from the sample a signal indicative of a second NMR spectrum before relaxation of the perturbed spins in the said first region, and comparing the said first and second signals to obtain a difference spectrum attributable to the said region. Three separate perturbing pulses are preferably employed, each in the presence of a corresponding field gradient. The experiment is preferably repeated a large number of times, with the Rf carrier frequency stepped between each Rf pulse (for example every 500 microseconds).

Method and apparatus for obtaining localized NMR spectra

A method of obtaining an NMR spectrum from a sample comprising the steps of: maintaining a static magnetic field along an axis which is homogeneous over at least a small volume constituting part of a sample applying a gradient to said magnetic field which varies in one direction orthogonal to said axis while applying an rf pulse to the sample to saturate all nuclei in the said volume except for a slab lying in a plane normal to the said one direction replacing the said gradient by a second gradient to said magnetic field which varies in a second direction orthogonal to said axis and said one direction while applying an rf pulse to the sample to saturate all nuclei in the said volume except for a slab lying in a plane normal to the said second direction, whereby nuclei in a narrow column extending parallel to the said axis have their spins left undisturbed replacing the second gradient by a third gradient to said static magnetic field which varies in a direction parallel to said axis while applying an rf pulse to the sample to selectively irradiate nuclei in a small region of the said column; and finally removing the third gradient and then reading out the free induction decay signal from the selectively irradiated nuclei in the presence of the static magnetic field alone.

Methods and apparatus of obtaining NMR spectra

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.y) has a given sense, and the free induction decay signals obtained when both gradients are present, and when only the first gradient is present, are separately processed. In a third proposed method, the first gradient (G.sub.y) is temporarily removed before each reversal of its sense, and the second gradient (G.sub.x) is reversed while the first gradient is removed, the magnitude of the second gradient being controlled so that the time integral of the second gradient at the beginning of each period when the first gradient has a given sense is the same as at the end of the preceding such period, the free induction decay signals occurring when the first gradient has said given sense only being used for data retrieval.

Growing community of inventors

Nottingham, United Kingdom

Roger J Ordidge