← Back to Patent Explorer
US5070299A Expired / Lapsed US ⏱️ 0.0 years remaining

Slice profile optimization for a nuclear magnetic resonance tomography apparatus operated with a gradient echo sequence

Assignee: Siemens AG
•
Filing: 1990-06-25
•
Granted: 1991-12-03
•
Expires: 2010-06-25
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract In a nuclear magnetic resonance tomography apparatus, for slice profile optimization, a pre-saturation RF pulse is generated in the presence of a slice selection gradient before the excitation RF pulse in a gradient echo sequence. The frequency spectrum of the pre-saturation RF pulse is defined so that it excites regions of the slice which correspond to the edges of the excitation RF pulse. A spoiler gradient in the z-direction is generated between the pre-saturation RF pulse and the excitation RF pulse. As a result of the pre-saturation RF pulse, the dependency of the slice profile on the flip angle of the excitation RF pulse and on the relationship T R /T 1 is reduced.

Inventors

  • 👤 Berthold Kiefer
  • 👤 Franz Schmitt

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-07 14:50
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/4818; G01R33/482; G01R33/483; G01R33/4838

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 160 words
In a method for operating a magnetic resonance imaging tomography apparatus using a gradient echo sequence including the steps of exciting nuclear spins in a slice of an examination subject by generating an excitation RF pulse in the presence of a slice selection gradient in a first direction, phase-coding the excited nuclear spins by a phase-coding gradient in a second direction perpendicular to said first direction to obtain a nuclear magnetic resonance signal, and reading out said nuclear magnetic resonance signal in the presence of a read-out gradient in a third direction perpendicular to said first and second directions, the improvement comprising: generating a pre-saturation RF pulse in said slice selected by said slice selection gradient before generating said excitation RF pulse, said presaturation RF pulse having a frequency spectrum which excites regions of said slice corresponding to the edges of said RF excitation pulse; and generating a spoiler gradient between said pre-saturation RF pulse and said excitation RF pulse.
Claim 2
Dependent Claim 160 words
In a method for operating a magnetic resonance imaging tomography apparatus using a gradient echo sequence including the steps of exciting nuclear spins in a slice of an examination subject by generating an excitation RF pulse in the presence of a slice selection gradient in a first direction, phase-coding the excited nuclear spins by a phase-coding gradient in a second direction perpendicular to said first direction to obtain a nuclear magnetic resonance signal, and reading out said nuclear magnetic resonance signal in the presence of a read-out gradient in a third direction perpendicular to said first and second directions, the improvement comprising: generating a pre-saturation RF pulse in said slice selected by said slice selection gradient before generating said excitation RF pulse, said presaturation RF pulse having a frequency spectrum which excites regions of said slice corresponding to the edges of said RF excitation pulse; and generating a spoiler gradient between said pre-saturation RF pulse and said excitation RF pulse.
Claim 3
Dependent Claim 44 words
The improvement of claim 1 wherein the step of generating a spoiler gradient is further defined by maintaining said slice selection gradient active between said pre-saturation RF pulse and said excitation RF pulse so that said slice selection gradient functions as said spoiler gradient.
Claim 4
Dependent Claim 36 words
The improvement of claim 1 wherein the step of generating a spoiler gradient is further defined by generating a separate spoiler gradient in said first direction between said pre-saturation RF pulse and said excitation RF pulse.
Claim 5
Dependent Claim 47 words
The improvement of claim 1 wherein completion of the step of reading out said nuclear magnetic resonance signal defines the end of a scan, and comprising the additional steps of: conducting a plurality of scans; and generating a pre-saturation RF pulse at a beginning of each scan.
Claim 6
Dependent Claim 50 words
The improvement of claim 1 wherein completion of the step of reading out said nuclear magnetic resonance signal defines the end of a scan, and comprising the additional steps of: conducting a plurality of scans; and generating only one pre-saturation RF pulse at a beginning of said plurality of scans.

References Cited (Backward Citations)

US4168462A Cited
US4506222A Cited
US4506222B1 Cited
US4521732A Cited
US4680546A Cited
US4733184A Cited
US4706024A Cited
US4701708A Cited
US4816764A Cited
DE3725705A1 Cited
US4849697A Cited
US5010300A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1994-12-02 1995-06-03 1995-12-03 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1998-12-02 1999-06-03 1999-12-03 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2002-12-02 2003-06-03 2003-12-03 $7700.00 Window Closed / Lapsed

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag