US6836114B2
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Pulse imaging sequences and methods for T1p-weighted MRI
Assignee: University of Pennsylvania
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Filing: 2003-03-14
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Granted: 2004-12-28
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Expires: 2023-03-14
Abstract
Abstract Provided are pulse imaging sequences and methods for 2D multi-slice T1rho-weighted and 3D T1rho-weighted magnetic resonance imaging (MRI). Further provided is a self-compensating spin-locking sequence for correcting and reducing artifacts in T1rho-weighted imaging. Also provided is a sequence combining 3D T1rho-weighted MRI with a self-compensating spin-locking pulse for facilitating T1rho-weighted imaging with surface coils.
Inventors
- 👤 Ravinder Reddy
- 👤 Sridhar R. Charagundla
- 👤 Ari Borthakur
- 👤 Erik M. Shapiro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:42
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/483; G01R33/4833; G01R33/4835; G01R33/50
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
104 words
A 2D multi-slice T 1ρ -weighted pulse sequence for magnetic resonance imaging, comprising in sequential order: a first radio frequency pulse for selectively exciting a band of spins; a second radio frequency pulse, wherein the second pulse is a spin-locking pulse divided into at least two segments, wherein the spin-locking segments have 90° alternating phase shift for spin-locking in a transverse plane of the spins; a third radio frequency slice-selective pulse, phase-shifted 180° from the first radio frequency pulse, which restores spin-locked magnetization to a longitudinal axis for imaging with any pulse sequence; and a strong crusher gradient applied to destroy residual transverse magnetization.
Claim 2
Dependent Claim
104 words
A 2D multi-slice T 1ρ -weighted pulse sequence for magnetic resonance imaging, comprising in sequential order: a first radio frequency pulse for selectively exciting a band of spins; a second radio frequency pulse, wherein the second pulse is a spin-locking pulse divided into at least two segments, wherein the spin-locking segments have 90° alternating phase shift for spin-locking in a transverse plane of the spins; a third radio frequency slice-selective pulse, phase-shifted 180° from the first radio frequency pulse, which restores spin-locked magnetization to a longitudinal axis for imaging with any pulse sequence; and a strong crusher gradient applied to destroy residual transverse magnetization.
Claim 3
Dependent Claim
21 words
The pulse sequence of claim 1 , wherein each of the first and third radio frequency pulses is a π/2 pulse.
Claim 4
Independent Claim
97 words
A method of magnetic resonance imaging using a 2D multi-slice T 1ρ -weighted sequence, comprising: applying a first radio frequency pulse for selectively exciting a band of spins; applying a spin-locking pulse, wherein the spin-locking pulse further comprises at least two segments with 90° alternating phase shift for spin-locking in a transverse plane of the spins; applying a third radio frequency slice-selective pulse, phase-shifted 180° from the first radio frequency pulse which restores spin-locked magnetization to a longitudinal axis for imaging with any pulse sequence; and applying a strong crusher gradient applied to destroy residual transverse magnetization.
Claim 5
Independent Claim
97 words
A method of magnetic resonance imaging using a 2D multi-slice T 1ρ -weighted sequence, comprising: applying a first radio frequency pulse for selectively exciting a band of spins; applying a spin-locking pulse, wherein the spin-locking pulse further comprises at least two segments with 90° alternating phase shift for spin-locking in a transverse plane of the spins; applying a third radio frequency slice-selective pulse, phase-shifted 180° from the first radio frequency pulse which restores spin-locked magnetization to a longitudinal axis for imaging with any pulse sequence; and applying a strong crusher gradient applied to destroy residual transverse magnetization.
Claim 6
Dependent Claim
23 words
The method of claim 3 , wherein applying each of the first and third radio frequency pulses further comprises applying a π/2 pulse.
Claim 7
Dependent Claim
99 words
A self-compensating spin-locking pulse sequence for correcting artifacts in T 1ρ -weighted magnetic resonance imaging, comprising in sequential order: a first radio frequency pulse for a selected θ that nutates magnetization into a transverse plane; a spin-locking pulse, wherein the spin-locking pulse further comprises at least two segments that are 90° phase-shifted and have an amplitude B s1 , applied for time period TSL; a second radio frequency pulse for a selected θ applied, phase-shifted by 180° to return a T 1ρ -relaxed magnetization to a longitudinal axis for imaging; and a crusher gradient to dephase residual transverse magnetization.
Claim 8
Dependent Claim
99 words
A self-compensating spin-locking pulse sequence for correcting artifacts in T 1ρ -weighted magnetic resonance imaging, comprising in sequential order: a first radio frequency pulse for a selected θ that nutates magnetization into a transverse plane; a spin-locking pulse, wherein the spin-locking pulse further comprises at least two segments that are 90° phase-shifted and have an amplitude B s1 , applied for time period TSL; a second radio frequency pulse for a selected θ applied, phase-shifted by 180° to return a T 1ρ -relaxed magnetization to a longitudinal axis for imaging; and a crusher gradient to dephase residual transverse magnetization.
Claim 9
Dependent Claim
24 words
The sequence of claim 5 , wherein each of the first and second radio frequency pulses for a selected θ is a π/2 pulse.
Claim 10
Independent Claim
113 words
A method of correcting artifacts in T 1ρ -weighted imaging with the self compensating spin-locking pulse, comprising applying a three-pulse preparatory cluster to an imaging sequence, including the following steps: applying a first radio frequency pulse for a selected θ that nutates magnetization into a transverse plane; applying a spin-locking pulse, wherein the spin-locking pulse further comprises at least two segments that are 90° phase-shifted and have an amplitude B s1 , applied for time period TSL; applying a second radio frequency pulse for a selected θ phase-shifted by 180° to return a T 1ρ -relaxed magnetization to a longitudinal axis for imaging; and applying a crusher gradient to dephase residual longitudinal magnetization.
Claim 11
Independent Claim
113 words
A method of correcting artifacts in T 1ρ -weighted imaging with the self compensating spin-locking pulse, comprising applying a three-pulse preparatory cluster to an imaging sequence, including the following steps: applying a first radio frequency pulse for a selected θ that nutates magnetization into a transverse plane; applying a spin-locking pulse, wherein the spin-locking pulse further comprises at least two segments that are 90° phase-shifted and have an amplitude B s1 , applied for time period TSL; applying a second radio frequency pulse for a selected θ phase-shifted by 180° to return a T 1ρ -relaxed magnetization to a longitudinal axis for imaging; and applying a crusher gradient to dephase residual longitudinal magnetization.
Claim 12
Dependent Claim
19 words
The method of claim 7 , further comprising applying the three-pulse preparatory cluster pre-appended to a spin-echo-based imaging sequence.
Claim 13
Dependent Claim
20 words
The method of claim 7 , further comprising applying the three-pulse preparatory cluster pre-appended to a gradient echo-based imaging sequence.
Claim 14
Dependent Claim
22 words
The method of claim 7 , wherein B s1 is a fraction of a maximum available radio frequency field B 1 .
Claim 15
Dependent Claim
21 words
The method of claim 7 , wherein each of the first and second radio frequency pulses is a π/2 hard pulse.
Claim 16
Dependent Claim
76 words
A 3D T 1ρ -weighted pulse sequence for magnetic resonance imaging, comprising a pulse cluster pre-encoded with a gradient echo sequence, wherein the pulse cluster further comprises in sequential order: a first π/2 hard pulse; a spin-locking pulse having amplitude B 1 ; a second π/2 hard pulse phase shifted 180° from the first hard pulse; and a strong crusher gradient applied to destroy residual magnetization in a transverse plane and inhibit formation of unwanted coherences.
Claim 17
Dependent Claim
76 words
A 3D T 1ρ -weighted pulse sequence for magnetic resonance imaging, comprising a pulse cluster pre-encoded with a gradient echo sequence, wherein the pulse cluster further comprises in sequential order: a first π/2 hard pulse; a spin-locking pulse having amplitude B 1 ; a second π/2 hard pulse phase shifted 180° from the first hard pulse; and a strong crusher gradient applied to destroy residual magnetization in a transverse plane and inhibit formation of unwanted coherences.
Claim 18
Dependent Claim
20 words
The pulse sequence of claim 12 , wherein the spin-locking pulse further comprises two or more segments with alternating phases.
Claim 19
Dependent Claim
24 words
The pulse sequence of claim 13 , wherein spin-locking pulse segments are +90° and −90° phase-shifted from the phase of the first π/2 pulse.
Claim 20
Independent Claim
82 words
A method for magnetic resonance imaging using a 3D T 1ρ -weighted pulse sequence, comprising applying a pulse cluster pre-encoded with a gradient echo sequence, wherein applying a pulse cluster further comprises; applying a first π/2 hard pulse; applying a spin-locking pulse having amplitude B 1 ; applying a second π/2 hard pulse phase shifted 180° from the first hard pulse; and applying a strong crusher gradient to destroy residual magnetization in a transverse plane and inhibit the formation of unwanted coherences.
Claim 21
Independent Claim
82 words
A method for magnetic resonance imaging using a 3D T 1ρ -weighted pulse sequence, comprising applying a pulse cluster pre-encoded with a gradient echo sequence, wherein applying a pulse cluster further comprises; applying a first π/2 hard pulse; applying a spin-locking pulse having amplitude B 1 ; applying a second π/2 hard pulse phase shifted 180° from the first hard pulse; and applying a strong crusher gradient to destroy residual magnetization in a transverse plane and inhibit the formation of unwanted coherences.
Claim 22
Dependent Claim
41 words
The method of claim 15 , wherein the step of applying a spin-locking pulse further comprises applying a spin-locking pulse having at least two segments, wherein the at least two spin-locking segments have alternating phases for spin-locking in a transverse plane.
Claim 23
Independent Claim
100 words
A method of obtaining 3D T 1ρ -weighted images with a coil, comprising applying a pulse cluster pre-encoded with a gradient echo sequence, wherein applying a pulse cluster further comprises; applying a first π/2 hard pulse; applying a spin-locking pulse having amplitude B 1 and having at least two segments, wherein the spin-locking segments have alternating phases for spin-locking in a transverse plane of the spins; applying a second π/2 hard pulse, phase shifted 180° from the first hard pulse; and applying a strong crusher gradient to destroy residual magnetization in the transverse plane and inhibit formation of unwanted coherences.
Claim 24
Independent Claim
100 words
A method of obtaining 3D T 1ρ -weighted images with a coil, comprising applying a pulse cluster pre-encoded with a gradient echo sequence, wherein applying a pulse cluster further comprises; applying a first π/2 hard pulse; applying a spin-locking pulse having amplitude B 1 and having at least two segments, wherein the spin-locking segments have alternating phases for spin-locking in a transverse plane of the spins; applying a second π/2 hard pulse, phase shifted 180° from the first hard pulse; and applying a strong crusher gradient to destroy residual magnetization in the transverse plane and inhibit formation of unwanted coherences.
Claim 25
Dependent Claim
13 words
The method of claim 17 , wherein the coil is a surface coil.
Claim 26
Dependent Claim
15 words
The method of claim 17 , wherein the coil is a volume radio frequency coil.
Claim 27
Dependent Claim
25 words
The method of claim 17 , wherein applying spin-locking segments further comprises applying spin-locking segments +90° and −90° phase shifted from the first hard pulse.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2007-12-28 | 2008-06-28 | 2008-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-12-28 | 2012-06-28 | 2012-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-12-28 | 2016-06-28 | 2016-12-28 | $7700.00 | Window Closed / Lapsed |