Asymmetrical gradient coil for head imaging

This work presents a novel approach to develop dedicated transverse gradient coils for head imaging. The proposed coil design is based on the stochastic optimization of an asymmetrical stream function and improves the matching between the region‐of‐interest and the homogeneous gradient volume. Additionally, the electric field produced by these asymmetrical coils is 30% lower than that produced by standard symmetrical designs, which minimizes the risk of magnetostimulation of nerves in fast imaging techniques. A prototype of the asymmetrical gradient coil was built to test the method and magnetic field produced by the prototype was measured. Magnetic field measurements and electrical parameters of coils are in good agreement with theoretical calculations. Magn Reson Med 48:707–714, 2002. © 2002 Wiley‐Liss, Inc.

[1]  Magnetic fields mapping with the phase reference method. , 1999, Magnetic resonance imaging.

[2]  P Mansfield,et al.  Limits to neural stimulation in echo‐planar imaging , 1993, Magnetic resonance in medicine.

[3]  D. Doddrell,et al.  Gradient-Coil Design by Simulated Annealing , 1993 .

[4]  W Irnich,et al.  Magnetostimulation in MRI , 1995, Magnetic resonance in medicine.

[5]  Dardo Tomasi,et al.  Shielded biplanar gradient coil design , 1999, Journal of magnetic resonance imaging : JMRI.

[6]  B. Rutt,et al.  Simple linear formulation for magnetostimulation specific to MRI gradient coils , 2001, Magnetic resonance in medicine.

[7]  D. Tomasi.  Stream function optimization for gradient coil design , 2001, Magnetic resonance in medicine.

[8]  S Crozier,et al.  A design methodology for short, whole-body, shielded gradient coils for MRI. , 1995, Magnetic resonance imaging.

[9]  S Y Lee,et al.  Planar gradient coil design by scaling the spatial frequencies of minimum‐inductance current density , 1997, Magnetic resonance in medicine.

[10]  R. Turner,et al.  Gradient coil design: a review of methods. , 1993, Magnetic resonance imaging.

[11]  K F King,et al.  Concomitant gradient field effects in spiral scans , 1999, Magnetic resonance in medicine.

[12]  A M Abduljalil,et al.  Torque free asymmetric gradient coils for echo planar imaging , 1994, Magnetic resonance in medicine.

[13]  S Crozier,et al.  An "openable," high-strength gradient set for orthopedic MRI. , 1999, Journal of magnetic resonance.

[14]  B. Rutt,et al.  Design and fabrication of a three‐axis edge ROU head and neck gradient coil , 2000, Magnetic resonance in medicine.

[15]  B. Rutt,et al.  Constrained length minimum inductance gradient coil design , 1998, Magnetic resonance in medicine.

[16]  Stuart Crozier,et al.  The Design of Transverse Gradient Coils of Restricted Length by Simulated Annealing , 1994 .

[17]  R M Weisskoff,et al.  Nonaxial whole‐body instant imaging , 1993, Magnetic resonance in medicine.

[18]  T. Carpenter,et al.  Design of a biplanar gradient coil using a genetic algorithm. , 1997, Magnetic resonance imaging.

[19]  R Bowtell,et al.  Analytic approach to the design of transverse gradient coils with co‐axial return paths , 1999, Magnetic resonance in medicine.

[20]  D Tomasi,et al.  Fast optimization of a biplanar gradient coil set. , 1999, Journal of magnetic resonance.

[21]  D. Alsop,et al.  Optimization of torque‐balanced asymmetric head gradient coils , 1996, Magnetic resonance in medicine.