Local bi‐planar gradient array design using conformal mapping and simulated annealing

Abstract

AbstractMany magnetic resonance imaging applications require high spatial and temporal resolution. The improved gradient performance required to achieve high spatial and temporal resolution may be achieved by using local gradient coils such as planar gradient inserts. The planar gradient set provides higher gradient performance because it is placed inside of the imaging bore of the magnet (within the body gradients) in close proximity to the imaging region. Although the wire patterns for planar gradients can be designed using two dimensional stream functions and simulated annealing, optimization of the two dimensional stream functions can be much more computationally intensive and time consuming than optimizing the one dimensional stream functions required for cylindrical gradients. To address this problem, we have developed a simple and rapid method for the design of planar gradient inserts to produce a high strength local gradient field and a reasonably uniform imaging region. By using conformal mapping, the two dimensional problem can be simplified to a faster and more easily calculated one dimensional problem. The mapping transforms the magnetic field and wire patterns in the cylindrical system into a magnetic field and wire patterns in the bi‐planar geometry providing a tool for bi‐planar gradient coil design using a one dimensional stream function. © 2009 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 35B: 23–31, 2009