US5498962A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Imaging method
Assignee: Philips Medical Systems MR Technologies Finland Oy
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Filing: 1994-03-10
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Granted: 1996-03-12
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Expires: 2014-03-10
Abstract
Abstract An SLP pulse is applied to an object to be imaged preceding one or more excitation pulses (a o or a) of a known magnetic resonance imaging technique. The SLP pulse tilts the nuclear magnetization away from the direction of B o , locks the magnetization with the rotating magnetic component and returns the magnetization back to the direction of B o . The known magnetic resonance imaging technique used with the SLP pulse includes applying at least one excitation pulse to generate transverse magnetization in the object. The excitation pulse causes the angle between the nuclear magnetization and B o to be less than 90°.
Inventors
- 👤 Raimo E. Sepponen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:19
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/483; G01R33/4833; G01R33/54; G01R33/56; G01R33/563; G01R33/56308
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
140 words
A method for the magnetic resonance imaging examination of an object using one of the known magnetic resonance imaging techniques, said method comprising the steps of: a. applying a radio frequency pulse to the object to tilt the nuclear magnetization from the direction of the polarizing magnetic field; b. allowing the tilted nuclear magnetization in the object to relax along the magnetic component of the radio frequency pulse for a locking period; c. orienting the nuclear magnetization parallel to the polarizing magnetic field; and d. applying a magnetic resonance imaging sequence to the object, said imaging sequence comprising: applying at least one excitation pulse to the object to generate transverse magnetization in the object such that after each of said at least one excitation pulse the angle between the nuclear magnetization and the polarizing magnetic field is less than 90°.
Claim 2
Independent Claim
140 words
A method for the magnetic resonance imaging examination of an object using one of the known magnetic resonance imaging techniques, said method comprising the steps of: a. applying a radio frequency pulse to the object to tilt the nuclear magnetization from the direction of the polarizing magnetic field; b. allowing the tilted nuclear magnetization in the object to relax along the magnetic component of the radio frequency pulse for a locking period; c. orienting the nuclear magnetization parallel to the polarizing magnetic field; and d. applying a magnetic resonance imaging sequence to the object, said imaging sequence comprising: applying at least one excitation pulse to the object to generate transverse magnetization in the object such that after each of said at least one excitation pulse the angle between the nuclear magnetization and the polarizing magnetic field is less than 90°.
Claim 3
Dependent Claim
51 words
A method according to claim 1 wherein a spin echo is generated by performing the further steps of applying a first magnetic field gradient for a first period and applying a second gradient such that the second gradient has a component which is opposite to the direction of the first gradient.
Claim 4
Dependent Claim
28 words
A method according to claim 1 further including applying a refocusing pulse after each of said at least one excitation pulse to generate one or more spin echoes.
Claim 5
Dependent Claim
16 words
A method according to claim 1 wherein the magnetic resonance imaging method is Fourier imaging method.
Claim 6
Dependent Claim
17 words
A method according to claim 1 further including the introduction of a contrast agent into the object.
Claim 7
Dependent Claim
17 words
A method according to claim 1 wherein the radio frequency pulse comprises an adiabatic half passage sweep.
Claim 8
Dependent Claim
43 words
A method according to claim 1 wherein at least two excitation pulses following the locking period, said excitation pulses generating a transverse magnetization such that the angle between the nuclear magnetization and the direction of the polarizing magnetic field is less than 90°.
Claim 9
Dependent Claim
26 words
A method according to claim 1 wherein at least two spatially selective excitation pulses are applied on different parts of the object in a predetermined order.
Claim 10
Dependent Claim
44 words
A method according to claim 1 wherein the at least one excitation pulse is spatially selective and the width of the area to be excited is predetermined such that a moving material fills the predetermined proportion of the area to be excited during TR.
Claim 11
Dependent Claim
26 words
A method according to claim 9 wherein a map of blood vessels in the object under examination is formed by using a maximum intensity projection method.
Claim 12
Dependent Claim
43 words
A method according to claim 1 further including, generating two or more images of the object by repeating steps a through d with different locking periods and different strengths of radio frequency pulse; and deriving information about the relaxation from the acquired images.
Claim 13
Dependent Claim
42 words
A method according to claim 1 further including acquiring two or more images of the object by repeating steps a through d, and introducing a paramagnetic substance into the object between the acquisition of two images of a part of the object.
Claim 14
Dependent Claim
26 words
A method according to claim 1 further including, acquiring two or more images of the same part of the object with locking pulses of different strengths.
Claim 15
Dependent Claim
17 words
A method according to claim 13 further including, deriving information about the relaxation from the collected images.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-03-12 | 1999-09-11 | 2000-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-03-12 | 2003-09-11 | 2004-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-03-12 | 2007-09-11 | 2008-03-12 | $7700.00 | Window Closed / Lapsed |