Gradient coil apparatus for magnetic resonance imaging

Abstract

A gradient coil assembly for a magnetic resonance imaging system comprising: a first gradient coil configured to generate a first gradient field in a first field of view; a second gradient coil configured to generate a second gradient field orthogonal to the first gradient field in a second field of view; and a third gradient coil configured to generate a third gradient field orthogonal to the first gradient field and the second gradient field in a plurality of fields of view.

1 . A gradient coil assembly for a magnetic resonance imaging system comprising: 
 an first gradient coil configured to generate a first gradient field in a first field of view;    a second gradient coil configured to generate a second gradient field orthogonal to said first gradient field in a second field of view; and    a third gradient coil configured to generate a third gradient field orthogonal to said first gradient field and said second gradient field in a plurality of fields of view.    
     
     
         2 . The gradient coil assembly of  claim 1  wherein said first gradient coil, said second gradient coil and said third gradient coil comprise an Z-axis, a X-axis and a Y-axis gradient coils respectively.  
     
     
         3 . The gradient coil assembly of  claim 1  wherein at least one of said first gradient coil and said second gradient coil comprise only a single gradient coil.  
     
     
         4 . The gradient coil assembly of  claim 1  wherein said plurality of fields of view comprises a wide field of view and a zoom field of view.  
     
     
         5 . A gradient coil assembly for a magnetic resonance imaging system comprising 
 an first gradient coil configured to generate a first gradient field in a single field of view;    a second gradient coil configured to generate a second gradient field orthogonal to said first gradient field in at least one field of view; and    a third gradient coil configured to generate a third gradient field orthogonal to said first gradient field and said second gradient field in a plurality of fields of view; and    wherein at least one of said first gradient coil and said second gradient coil comprise only a single coil and said third gradient coil comprises a plurality coils configured to generate said plurality of fields of view.    
     
     
         6 . The gradient coil assembly of  claim 5  wherein said first gradient coil, said second gradient coil and said third gradient coil comprise an Z-axis, a X-axis and a Y-axis gradient coils respectively.  
     
     
         7 . The gradient coil assembly of  claim 5  wherein said plurality of fields of view comprises a wide field of view and a zoom field of view.  
     
     
         8 . A method for decreasing gradient field pulse sequence duration for a magnetic resonance imaging system, the method comprising: 
 establishing an allowable gradient field strength for an axis of a plurality of axes for a field of view;    applying a weighting factor associated with each said axis of said plurality of axes;    establishing a slew rate responsive to a selected axis of said plurality of axes that exhibits a largest gradient field strength in light of said weighting factor and said field of view; and    operating said plurality of axes at said largest gradient field strength.    
     
     
         9 . The method of  claim 8  wherein said establishing is responsive to an effective gradient coil length.  
     
     
         10 . The method of  claim 8  wherein said weighting factor is one of a plurality of weighting factors corresponding to comparative allowable gradient field strengths among said plurality of axes.  
     
     
         11 . The method of  claim 8  wherein said plurality of axes correspond to an X, Y, and Z axes of said magnetic resonance imaging system.  
     
     
         12 . The method of  claim 8  wherein said operating includes limiting a gradient field strength of only said selected axis of said plurality of axes.  
     
     
         13 . A method for reducing peripheral nerve stimulation for a magnetic resonance imaging system, the method comprising: 
 establishing an allowable gradient field strength for an axis of a plurality of axes for a field of view;    applying a weighting factor associated with each said axis of said plurality of axes;    establishing a slew rate responsive to a selected axis of said plurality of axes that exhibits a largest gradient field strength in light of said weighting factor and said field of view; and    operating said plurality of axes at said largest gradient field strength.    
     
     
         14 . The method of  claim 13  wherein said establishing is responsive to an effective gradient coil length.  
     
     
         15 . The method of  claim 13  wherein said weighting factor is one of a plurality of weighting factors corresponding to comparative allowable gradient field strengths among said plurality of axes.  
     
     
         16 . The method of  claim 13  wherein said plurality of axes correspond to an X, Y, and Z axes of said magnetic resonance imaging system.  
     
     
         17 . The method of  claim 13  wherein said operating includes limiting a gradient field strength of only said selected axis of said plurality of axes.  
     
     
         18 . A system for decreasing gradient field pulse sequence duration in a magnetic resonance imaging system, comprising: 
 a magnetic resonance imaging system including a gradient coil assembly for a magnetic resonance imaging system comprising: 
 an first gradient coil configured to generate a first gradient field in a first field of view;  
 a second gradient coil configured to generate a second gradient field orthogonal to said first gradient field in a second field of view; and  
 a third gradient coil configured to generate a third gradient field orthogonal to said first gradient field and said second gradient field in a plurality of fields of view.  
   
     
     
         19 . The system of  claim 18  wherein said first gradient coil, said second gradient coil and said third gradient coil comprise an Z-axis, a X-axis and a Y-axis gradient coils respectively.  
     
     
         20 . The system of  claim 18  wherein at least one of said first gradient coil and said second gradient coil comprise only a single gradient coil.  
     
     
         21 . The system of  claim 18  wherein said plurality of fields of view comprises a wide field of view and a zoom field of view.  
     
     
         22 . A system for reducing peripheral nerve stimulation in a magnetic resonance imaging system, comprising: 
 a magnetic resonance imaging system including a gradient coil assembly for a magnetic resonance imaging system comprising: 
 an first gradient coil configured to generate a first gradient field in a first field of view;  
 a second gradient coil configured to generate a second gradient field orthogonal to said first gradient field in a second field of view; and  
 a third gradient coil configured to generate a third gradient field orthogonal to said first gradient field and said second gradient field in a plurality of fields of view.  
   
     
     
         23 . A storage medium encoded with a machine-readable computer program code; 
 said code including instructions for causing a computer to implement a method for reducing peripheral nerve stimulation for a magnetic resonance imaging system, the method comprising: 
 establishing an allowable gradient field strength for an axis of a plurality of axes for a field of view;  
 applying a weighting factor associated with each said axis of said plurality of axes;  
 establishing a slew rate responsive to a selected axis of said plurality of axes that exhibits a largest gradient field strength in light of said weighting factor and said field of view; and  
 operating said plurality of axes at said largest gradient field strength.  
   
     
     
         24 . A computer data signal comprising code configured to cause a processor to implement a method for reducing peripheral nerve stimulation in a magnetic resonance imaging system, the method comprising: 
 establishing an allowable gradient field strength for an axis of a plurality of axes for a field of view;    applying a weighting factor associated with each said axis of said plurality of axes;    establishing a slew rate responsive to a selected axis of said plurality of axes that exhibits a largest gradient field strength in light of said weighting factor and said field of view; and    operating said plurality of axes at said largest gradient field strength.    
     
     
         25 . A system for decreasing gradient field pulse sequence duration and reducing peripheral nerve stimulation with known gradient pulse areas for a magnetic resonance imaging system, the method comprising: 
 a means for establishing an allowable gradient field strength for an axis of a plurality of axes for a field of view;    a means for applying a weighting factor associated with each said axis of said plurality of axes;    a means for establishing a slew rate responsive to a selected axis of said plurality of axes that exhibits a largest gradient field strength in light of said weighting factor and said field of view; and    a means for operating said plurality of axes at said largest gradient field strength.