EP0182481A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A method of, and apparatus for, determining fluid movement using nuclear magnetic resonance
Assignee: Leland Stanford Junior University
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Filing: 1985-10-07
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Granted: —
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Expires: 2005-10-07
Abstract
Abstract A modified spin echo sequence is employed to identify fuild movement in a material. The volume of interest is subject to a static field along one axis (Z) and an RF magnetic excitation pulse transverse to the static field is applied which tilts the nuclear spins in the volume. The tilted nuclear spins are then allowed to precess about the uniform static field in the presence of a gradient field whereby the nuclear spins become dephased. Thereafter, a spin echo of the static spins is created by either a 180° RF pulse or reversal of the gradient field. Upon refocusing of the static nuclear spins a restoration RF pulse is applied to realign the stationary nuclear spins with the static field. Nuclear spins undergoing bulk motion as in fluid flow will be refocused to a different phase than the stationary spins so that the final RF pulse will in general leave these residual spins with a non-zero transverse magnetic moment. Such residual transverse magnetic spins are then detected to identify the fluid movement.
Inventors
- 👤 Michael Allan Taber
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 10:08
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/563; G01R33/56308; G01R33/56316
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
88 words
A method of determining fluid movement in a material, characterised by the steps of applying a static magnetic field to said material thereby aligning nuclear spins; applying a first RF magnetic pulse to said material thereby tilting said nuclear spins; applying a gradient field to said nuclei whereby said nuclear spins become dephased; refocusing said dephased nuclear spins; applying a restoration RF magnetic pulse to said nuclear spins upon refocusing of said nuclear spins; and identifying residual transverse nuclear spins in said material as indicative of moving nuclei.
Claim 2
Independent Claim
88 words
A method of determining fluid movement in a material, characterised by the steps of applying a static magnetic field to said material thereby aligning nuclear spins; applying a first RF magnetic pulse to said material thereby tilting said nuclear spins; applying a gradient field to said nuclei whereby said nuclear spins become dephased; refocusing said dephased nuclear spins; applying a restoration RF magnetic pulse to said nuclear spins upon refocusing of said nuclear spins; and identifying residual transverse nuclear spins in said material as indicative of moving nuclei.
Claim 3
Dependent Claim
49 words
A method as claimed in Claim 1, characterised in that said nuclei are selectively excited in a planar slice by means of the step of superimposing a gradient magnetic field on said static magnetic field, said first RF magnetic pulse being at the Larmor frequency for said planar slice.
Claim 4
Dependent Claim
28 words
A method as claimed in Claim 1 or Claim 2, characterised in that said step.of identifying residual nuclear spins includes detecting FID signals from said residual nuclear spins.
Claim 5
Dependent Claim
36 words
A method as claimed in Claim 3, characterised by the step of selectively applying a gradient magnetic field to said residual nuclear spins during the detecting of FID signals to determine the location of moving nuclei.
Claim 6
Dependent Claim
19 words
S. A method as claimed in any preceding claim, characterised by the step of imaging said residual nuclear spins.
Claim 7
Independent Claim
19 words
A method as claimed in any preceding claim, characterised in that said movement is blood flow in a body.
Claim 8
Dependent Claim
100 words
Apparatus for determining fluid movement in a material, characterised by means for applying a static magnetic field to said material, means for applying an RF magnetic pulse to said material thereby tilting nuclear spins in said material, means for applying a gradient field to said nuclei whereby said nuclear spins become dephased, means for refocusing said dephased nuclear spins to produce a spin echo, means for applying a restoration RF magnetic pulse to said nuclear spins upon refocusing of said nuclear spins of static nuclei, and means for identifying residual nuclear spins in said material as indicative of moving nuclei.
Claim 9
Dependent Claim
100 words
Apparatus for determining fluid movement in a material, characterised by means for applying a static magnetic field to said material, means for applying an RF magnetic pulse to said material thereby tilting nuclear spins in said material, means for applying a gradient field to said nuclei whereby said nuclear spins become dephased, means for refocusing said dephased nuclear spins to produce a spin echo, means for applying a restoration RF magnetic pulse to said nuclear spins upon refocusing of said nuclear spins of static nuclei, and means for identifying residual nuclear spins in said material as indicative of moving nuclei.
Claim 10
Dependent Claim
39 words
Apparatus as claimed in Claim 7, wherein said nuclei are in a plane, characterised by means for superimposing a gradient magnetic field on said static magnetic filed, said RF magnetic pulse being at the Larmor frequency for said plane.
Claim 11
Dependent Claim
30 words
Apparatus as claimed in Claim 7 or Claim 8, characterised in that said means for identifying residual nuclear spins includes means for detecting FID signals from said residual nuclear spins.
Claim 12
Dependent Claim
31 words
Apparatus as claimed in Claim 9, characterised by means for selectively applying a gradient field to said residual nuclear spins during the detecting of FID signals thereby to detect moving nuclei.
References Cited (Backward Citations)
No citation records indexed.
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