Nuclear magnetic resonance method and apparatus

Claim 2

A nuclear magnetic resonance method for imaging a region of a body in which part of the region is moving with a motion such that its displacement with respect to time is anonmonotonic function during the time period over which a plurality of NMR data signals are collected which together define an image characterised in that the data signals are collected in an order dependent on the motion such that motion artefacts are reduced.

Claim 3

A method according to Claim 1 in which pulses v; a phase encoding magnetic gradient field (Gy) are applied with a respective NMR data signal being collected after each pulse, the pulses being applied in such an order as to cause the relationship between the displacement (d) of the moving part of the region at any one time and the value of the time integral of the pulse to tend towards a predetermined function.

Claim 4

A method according to Claim 1 in which a frequency encoding magnetic gradient field is used to define a plurality of parallel strips across the region, an NMR data signal being collected from the strips, the strips being caused to rotate across the region in successive data collection periods by variation of the direction of the field, such that the relationship between the angle which the strips make with an initial direction across the region at any one time and the displacement of the part of the region at that time tends towards a predetermined function.

Claim 5

A method according to Claim 2 or Claim 3 in which the predetermined function is a monotonic function.

Claim 7

A nuclear magnetic resonance apparatus for imaging a region of a body in which part of the region is moving with a motion such that its displacement with respect to time is a nonmonotonic function during the time period over which a plurality of NMR data signals which together define an image are collected the apparatus being characterised in that it includes means (10A, 10B, 29) for collecting the data signals in an order dependent on the motion such that motion artefacts are reduced.

Claim 8

A nuclear magnetic resonance apparatus for imaging a region of a body in which part of the region is moving with a motion such that its displacement with respect to time is a nonmonotonic function during the time period over which a plurality of NMR data signals which together define an image are collected the apparatus being characterised in that it includes means (10A, 10B, 29) for collecting the data signals in an order dependent on the motion such that motion artefacts are reduced.

Claim 9

An apparatus according to Claim 6 including means (5, 29) for applying pulses of a phase encoding magnetic gradient field (Gy) in an order as to cause the relationship between the displacement (d) of the moving part of the region at any one time and the value of the time integral of the phase encoding gradient pulse at the time to tend towards a predetermined function ; and means for collecting a respective NMR data signal after each pulse.

Claim 10

An apparatus according to Claim 6 including means (3, 5, 29) for applying a frequency encoding magnetic gradient field effective to define a plurality of parallel strips across the region and means for varying the direction of the fields so as to cause the strips to rotate across the region in successive data colection periods the direction of the fields being varied such that the relationship between the angle which the strips make with an initial direction across the region at any one time and the displacement of the moving part of the region at that time tends towards a predetermined function; and means (10A, 10B) for collecting an NMR data signal from the strips at each position.