Nuclear magnetic resonance detection method and apparatus

Claim 3

A method of producing an N.M.R. picture of a plane through an object as claimed in Claim 1 characterised in that at each position of orientation of the directional magnetic field a multiplicity of pulses of R.F. frequency magnetic field are used to provide the N.M.R. response for each particular orientation by averaging the multiplicity of N.M.R. responses.

Claim 4

Apparatus for producing an N.M.R. picture of a plane through an object including a first set of coils for generating an extremely high constant magnetic field, characterised in that the apparatus also includes a second set of coils (14, 14', 16, 16', or 18, 18') for generating an oscillating field the intensity of which varies across the object except at a selected plane where the oscillating field is substantially zero, and a third set of coils (14, 14', 16, 16', or 18,18') for generating a directional magnetic field, said second and third sets of coils being interchangeable in role, first control means (30, 32, 31, 34) connected to the third set of coils for generating a set program to control the orientation of the directional magnetic field, a fourth set of coils (22) for subjecting the object to an R.F. magnetic field, second control means (38) connected to the fourth set of coils for generating R.F. signals at required intervals, detection means (22) for detecting the N.M.R. responses recording means (44) for recording the N.M.R. responses from each position of orientation of the directional magnetic field and means (46) for generating from the recorded N.M.R. responses the N.M.R. picture.

Claim 5

Apparatus for producing an N.M.R. picture of a plane through an object including a first set of coils for generating an extremely high constant magnetic field, characterised in that the apparatus also includes a second set of coils (14, 14', 16, 16', or 18, 18') for generating an oscillating field the intensity of which varies across the object except at a selected plane where the oscillating field is substantially zero, and a third set of coils (14, 14', 16, 16', or 18,18') for generating a directional magnetic field, said second and third sets of coils being interchangeable in role, first control means (30, 32, 31, 34) connected to the third set of coils for generating a set program to control the orientation of the directional magnetic field, a fourth set of coils (22) for subjecting the object to an R.F. magnetic field, second control means (38) connected to the fourth set of coils for generating R.F. signals at required intervals, detection means (22) for detecting the N.M.R. responses recording means (44) for recording the N.M.R. responses from each position of orientation of the directional magnetic field and means (46) for generating from the recorded N.M.R. responses the N.M.R. picture.

Claim 6

Apparatus for producing an N.M.R. picture of a plane through an object as claimed in Claim 3, characterised in that the first, second and third set of coils are arranged around a gap (10) within which the object to be examined is placed.

Claim 7

Apparatus for producing an N.M.R. picture of a plane through an object as claimed in Claim 4 characterised in that the first set of coils (12, 12') comprises four coils wound circumferentially around the gap and spaced apart along the axis of the tube.

Claim 8

Apparatus for producing an N.M.R. picture of a plane through an object as claimed in Claim 5, characterised in that the second set of coils comprises a first and second pair of x (16, 16') coils and a first and a second pair of y coils (14,14') the first pair of x and y coils (16, 14) being mounted radially opposite one another in a position on one side of said gap and the second pair of x and y coils (16', 14') being mounted radially opposite one another on the other side of said gap, the x and y coils being mounted orthogonally with respect to each other to provide magnetic fields at right angles to each other.

Claim 9

Apparatus for producing an N.M.R. picture of a plane through an object as claimed in Claim 4 characterised in that the fourth set of coils (22) for detecting the N.M.R. response are in the form of a crossed ellipse surrounding the object and situated in the gap.

Claim 10

Apparatus for producing an N.M.R. picture of a plane through an object as claimed in Claim 4 characterised in that the third set of coils (14, 14', 16, 16', or 18, 18') are provided with continuously changing signals to produce a continuous rotation of the field gradient.

Claim 11

Apparatus for producing an N.M.R. picture of a plane through an object as claimed in Claim 4, characterised in that the third set of coils (14, 14', 16, 16', or 18, 18') are provided with signals which are increased in a stepwise manner to produce a.step increase in the field gradient.

Claim 12

Apparatus for producing an N.M.R. picture of a plane through an object as claimed in Claim 3 characterised in that the second and third sets of coils (14, 14', 16, 16', and 18, 18') are constructed to have the same reluctance so as to be able to be interchangeably driven by the same pulse generator.