Local planar gradients with order‐of‐magnitude strength and speed advantage

Abstract

A three-axis uniplanar gradient coil was designed and built to provide order-of-magnitude increases in gradient strength of up to 500 mT/m on the x-and y-axes, and 1000 mT/m for the z-axis at 640 A input over a limited FOV (ϳ16 cm) for superficial regions, compared to conventional gradient coils, with significant gradient strengths extending deeper into the body. The gradient set is practically accommodated in the bore of a conventional whole-body, cylindrical-geometry MRI scanner, and operated using standard gradient supplies

A uniplanar three-axis gradient set for in vivo magnetic resonance microscopy

“…Optimized biplanar coil windings for finite areas and minimum inductance have been reported using methods such as stream function representation of current density that are also applicable to uniplanar gradient geometries. Uniplanar or surface gradient coil designs [23][24][25][26][27][28] have not received as much attention since cylindrical or biplanar gradient coils meet the requirements of most applications and avoid some of the design and operational complexities inherent in uniplanar designs. Dodd and Ho describe both uniplanar and biplanar microscopy gradient designs with discrete wire concentric return paths intended for very high resolution imaging of small samples [29].…”

Monoplanar gradient system for imaging with nonlinear gradients

“…SEMs generated by the prototype encoding system have been shown to be locally orthogonal; they are, therefore, suitable for encoding a cylindrical volume with a diameter of approximately 350 mm, which is larger than for other monoplanar setups built previously [4][5][6][7] and is sufficient for some abdomen imaging applications in humans. The first in-vivo images have been presented in this paper; further studies are in progress.…”

“…Despite those ig. 5 Hand-built coil elements before casting. In the layer of channel 1 (left image) two extra elements were incorporated which can be connected separately.…”

“…Previously built setups have been optimized for micro imaging [6] or only implemented one channel [4,7]. The single comparable study achieved a usable volume of approximately 160 mm [5].…”

“…Previous studies enforced approximate linearity over a reduced volume for monoplanar gradients to accommodate the unavoidable field decay or were specifically designed for small target volumes [4][5][6][7]. In our recent studies [8][9][10] we have shown that reasonable spatial encoding can be achieved as long as the local gradients of the encoding fields are non-collinear and have a non-zero magnitude.…”