EP0109238A2
Expired / Lapsed
EP
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Nuclear magnetic resonance method and apparatus
Assignee: Philips Design Ltd
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Filing: 1983-11-04
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Granted: —
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Expires: 2003-11-04
Abstract
Abstract A method of nuclear magnetic resonance imaging of a body in which the spins of a chosen nucleus in a selected slice (43) of the body are rotated through an angle appreciably greater than 90° by applying, in sequence, two substantially identical r.f. pulses (B 1 (90°), B 2 (90°)) accompanied by a magnetic field having a gradient (G 1 z, G 2 z) in a direction orthogonal to the plane of the slice (43). Each r.f. pulse is at the Larmor frequency for the chosen nuclei in the slice (43), and is effective to rotate the spins by not greater than 90° and the r.f. pulses together are sufficient to rotate the spins through the angle. The gradients of the magnetic fields are in opposite directions.
Inventors
- 👤 Ian Robert Young
- 👤 David Robert Bailes
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 19:11
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/4818; G01R33/482
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
171 words
A method of obtaining a representation of the spatial distribution of a quantity relating to nuclear magnetic resonance in a selected slice (43) of a body wherein rotation of the spins of a chosen nucleus within the selected slice (43) about an axis (X )perpendicular to the equilibrium axis of magnetic alignment of the spins through an angle appreciably greater than 90° is effected characterised in that: two r.f. pulses (B 1 (90°), B 2 (90°)) each accompanied by a magnetic field having a gradient (G 1 z, G 2 z) in a direction parallel to said equilibrium axis are applied in sequence, each r.f. pulse being at the Larmor frequency for said nuclei in said slice (43) in the presence of the associated field gradient (G 1 z, G 2 z) and each r.f. pulse being effective to rotate said spins by not greater than 90°, the r.f. pulses together being sufficient to rotate the spins through said angle, and the gradients of said magnetic fields being in opposite directions.
Claim 2
Independent Claim
171 words
A method of obtaining a representation of the spatial distribution of a quantity relating to nuclear magnetic resonance in a selected slice (43) of a body wherein rotation of the spins of a chosen nucleus within the selected slice (43) about an axis (X )perpendicular to the equilibrium axis of magnetic alignment of the spins through an angle appreciably greater than 90° is effected characterised in that: two r.f. pulses (B 1 (90°), B 2 (90°)) each accompanied by a magnetic field having a gradient (G 1 z, G 2 z) in a direction parallel to said equilibrium axis are applied in sequence, each r.f. pulse being at the Larmor frequency for said nuclei in said slice (43) in the presence of the associated field gradient (G 1 z, G 2 z) and each r.f. pulse being effective to rotate said spins by not greater than 90°, the r.f. pulses together being sufficient to rotate the spins through said angle, and the gradients of said magnetic fields being in opposite directions.
Claim 3
Dependent Claim
21 words
A method according to Claim 1 in which a first further magnetic field having a gradient (3 3 z) is applied.
Claim 4
Dependent Claim
62 words
A method according to Claim 2 in which said first further magnetic field (G 3 z) is applied after said second r.f. pulse (B 2 (90°)) and a second further magnetic field having a gradient is applied before the first (B 1 (90°)) of said two r.f. pulses, said second further gradient being in the opposite direction to said first further gradient.
Claim 5
Independent Claim
16 words
A method according to any one of the preceding claims in which said angle is 180°.
Claim 6
Independent Claim
27 words
A method according to any one of the preceding claims in which said two r.f. pulses (B 1 (90°), B 2 (90 o )) are substantially identical.
Claim 7
Independent Claim
179 words
An apparatus arranged to obtain a representation of the spatial distribution of a quantity relating to nuclear magnetic resonance in a selected slice (43) of a body wherein rotation of the spins of a chosen nucleus within the selected slice about an axis perpendicular to the equilibrium axis of magnetic alignment of the spins through an angle appreciably greater than 90 0 is effected, characterised in that the apparatus includes: means (1, 7, 9) arranged to apply in sequence two r.f. pulses (B 1 (90°), B 2 (90°)) each accompanied by a magnetic field having a gradient (G 1 z, G 2 z) in a direction parallel to said equilibrium axis, each r.f. pulse being at the Larmor frequency for said nuclei in said slice (43) in the presence of the associated field gradient, and each r.f. pulse being effective to rotate said spins by not greater than 90°, the r.f. pulses together being sufficient to rotate said spins through said angle, and the gradients (G l z, G 2 2) of said magnetic fields being in opposite directions.
Claim 8
Independent Claim
179 words
An apparatus arranged to obtain a representation of the spatial distribution of a quantity relating to nuclear magnetic resonance in a selected slice (43) of a body wherein rotation of the spins of a chosen nucleus within the selected slice about an axis perpendicular to the equilibrium axis of magnetic alignment of the spins through an angle appreciably greater than 90 0 is effected, characterised in that the apparatus includes: means (1, 7, 9) arranged to apply in sequence two r.f. pulses (B 1 (90°), B 2 (90°)) each accompanied by a magnetic field having a gradient (G 1 z, G 2 z) in a direction parallel to said equilibrium axis, each r.f. pulse being at the Larmor frequency for said nuclei in said slice (43) in the presence of the associated field gradient, and each r.f. pulse being effective to rotate said spins by not greater than 90°, the r.f. pulses together being sufficient to rotate said spins through said angle, and the gradients (G l z, G 2 2) of said magnetic fields being in opposite directions.
Claim 9
Dependent Claim
24 words
An apparatus according to Claim 6 including means arranged to apply a first further magnetic field having a gradient ( G 3 z ).
Claim 10
Dependent Claim
57 words
An apparatus according to Claim 9 including means arranged to apply said first further magnetic field (G3z) after said second r.f. pulse (B 2 (90°)) and a second further magnetic field having a gradient before the first (B1(90°)) of said two r.f. pulses, said second further gradient being in the opposite direction to said first further gradient.
Claim 11
Independent Claim
27 words
An apparatus according to any one of Claims 6 to 8 in which said two r.f. pulses (B 1 (90°), B 2 (90°)) are substantially identical .
References Cited (Backward Citations)
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