The document provides an overview of MRI gradient coils, which are essential components that create varying magnetic fields to enable spatial encoding of MRI signals. It discusses the traditional and modern manufacturing methods of these coils and their role in various imaging techniques. Additionally, the document offers resources for assistance and information regarding MRI equipment from Atlantis Worldwide.

1. Sensible Solutions for Refurbished Radiology
MRI Gradient Coils: 101
By: Vikki Harmonay

2. Sensible Solutions for Refurbished Radiology
Sometimes it’s great to review the basics of Magnetic Resonance
Imaging; how they work, what they cost, how they’re maintained
and even how they are installed. Let’s take a closer look at Gradient
Coils in MRI scanners.

3. Sensible Solutions for Refurbished Radiology
Gradients are simply loops of wire or thin conductive sheets on a
cylindrical shell that lies just inside the bore of an MRI Scanner.
When an electrical current passes through these coils, the result is a
secondary magnetic field. This gradient field distorts the main
magnetic field in a slight but predictable pattern. This causes the
resonance frequency of protons to vary in a function of position.
The main function of gradients is to allow spatial encoding of the
MRI signal, but are also critical for a wide range of physiologic
techniques. Examples includes MR angiography, diffusion ad
perfusion imaging.

4. Sensible Solutions for Refurbished Radiology
MRI gradient coils traditionally were composed of individual wires
wrapped onto fiberglass cylindrical formers coated with epoxy resin.
While this method is still used on many very-high-field human
scanners and laboratory instruments, most widely manufacturer
superconducting scanners now use distributed windings in a
“fingerprint” pattern. They consist of multiple thin metallic strips or
large copper sheets that have been etched into complex patterns and
applied to the cylinder.

5. Sensible Solutions for Refurbished Radiology
Almost all MR systems use three sets of gradient coils the x-, y- and
z-gradients. An independent power amplifier drives each coil set,
which creates a gradient field whose z-component varies linearly
along the x-, y- and z-directions respectively. The x- and y- gradients
usually have a saddle (Golay) coil configuration and the z- gradients
is usually based on circular (Maxwell) coils. The z -gradient is
produced by using two coils carrying currents in opposite direction.

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When a gradient is applied, it causes a frequency variation of protons
as a function of position along the direction of the gradient, which
can be used for spatial encoding. If the gradient is played out during
slice selection, as well as during signal readout, a slice can be
selected perpendicular to the gradient direction. If, for example, the
z- gradient is turned on in this way, a transverse slice is created in a
supine patient. By turning on two of more gradients simultaneously,
oblique slices can be obtained.

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If you have questions about gradient coils, it’s always wise to talk to
an expert. At Atlantis Worldwide, we’re happy to provide information
or recommendations about MRI, CT Scanners, C-Arms and other
Medical imaging equipment. For more than 30 years, we’ve helped
hospital and healthcare administrators, purchasers, radiology
professionals and physicians determine which MRI equipment is right
for their practice or facility and if refurbished or used equipment is a
wise and economically sound solution. Please feel free to reach out
to us anytime!
Talk To An Expert

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https://info.atlantisworldwide.com/blog/mri-gradient-
coils-101

9. Sensible Solutions for Refurbished Radiology
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