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A transverse gradient coil design is described for wire wound cylindrical applications. The proposed design is aimed for use as a fixed gradient coil or as an insertable gradient coil. Although we describe a transverse gradient coil for clinical MRI scanners, the principle could be applied for use in preclinical systems. The gradient coil wire wound return paths are altered to allow for the ends of the gradient coil to be wrapped into the transverse plane of the MRI system to reduce the effect of their contribution to the magnetic field within the FoV. In essence, this new configuration reduces the inductance of the coil by decreasing the primary path and return path interactions, and in addition, minimising field oscillations to reduce peripheral nerve stimulation. The proposed design produces a large FoV, low coil inductance and small high order harmonics contributing to improved gradient magnetic field linearity. The proposed concept is particularly aimed at short bore magnets, as the length of the gradient tube becomes the limiting factor in magnet system bore length. © 2009 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 35B: 139-152, 2009

The aim of this article is to describe superconducting magnet coil arrangements from low to high field, particularly from 1T to 7T, within the context of the minimum stored energy designs. The findings illustrate that at low field, the maximum peak magnetic fields are located away from the most inner coils of the magnet configuration, whereas in high field designs, the maximum peak magnetic fields are created on coils lying on the inner diameter of the magnet bore. This becomes a critical aspect of any high field design, since there appears to be much less freedom of design at higher fields, due to the inherent limitations posed by peak magnetic fields on superconductors. Our findings also indicate that at low fields, 3T and less, reverse current coils can be used to shorten superconducting magnets, whereas at high field, above 3T, this is not necessarily the case, due to the large peak fields produced between adjacent, alternating current coils.

The aim of the research described here is to design head gradient coils using approaches previously developed by the authors. The wave equation method for designing gradient coils is used to design a transverse gradient coil winding on a cylindrical/spherical former. The results are compared with asymmetric cylindrical designs and other well-known head gradient coil designs to establish the quality of the gradient coil winding. Comparisons of field, inductance, torque, and other quality factors are made before conclusions are drawn about the adequacy of such a winding pattern to perform high-resolution imaging of the head. We show that it is possible to generate a robust winding pattern that has good efficiency and produces a sufficiently large imaging volume. (c) 2007 Wiley Periodicals, Inc.

A primary purpose of this research is to design a gradient coil that is planar in construction and can be inserted within existing infrastructure. The proposed wave equation method for the design of gradient coils is novel within the field. it is comprehensively shown how this method can be used to design the planar x-, y-, and z-gradient wire windings to produce the required magnetic fields within a certain domain. The solution for the cylindrical gradient coil set is also elucidated. The wave equation technique is compared with the well-known target held method to gauge the quality of resultant design. In the case of the planar gradient coil design, it is shown that using the new method, a set of compact gradient coils with large field of view can be produced. The final design is considerably smaller in dimension when compared with the design obtained using the target field method, and therefore the manufacturing costs and materials required are somewhat reduced.

In this work a superposition technique for designing gradient coils for the purpose of magnetic resonance imaging is outlined, which uses an optimized weight function superimposed upon an initial winding similar to that obtained from the target field method to generate the final wire winding. This work builds on the preliminary work performed in Part I on designing planar insertable gradient coils for high resolution imaging. The proposed superposition method for designing gradient coils results in coil patterns with relatively low inductances and the gradient coils can be used as inserts into existing magnetic resonance imaging hardware. The new scheme has the capacity to obtain images faster with more detail due to the deliver of greater magnetic held gradients. The proposed method for designing gradient coils is compared with a variant of the state-of-the-art target field method for planar gradient coils designs, and it is shown that the weighted superposition approach outperforms the well-known the classical method.

In this work a new approach for designing planar gradient coils is outlined for the use in an existing MRI apparatus. A technique that allows for gradient field corrections inside the diameter-sensitive volume is deliberated. These corrections are brought about by making changes to the wire paths that constitute the coil windings, and hence, is called the path correction method. The existing well-known target held method is used to gauge the performance of a typical gradient coil. The gradient coil design methodology is demonstrated for planar openable gradient coils that can be inserted into an existing MRI apparatus. The path corrected gradient coil is compared to the coil obtained using the target field method. It is shown that using a wire path correction with optimized variables, winding patterns that can deliver high magnetic gradient field strengths and large imaging regions can be obtained.