How can a zipper MRI artifact be limited to a single line?

In summary, the herringbone or spike MRI artifact occurs when a certain RF wave emitted by the patient is distorted by extraneous RF interference and affects the whole image in a striped pattern after being sampled through a DFT process into Fourier space. On the other hand, the zipper artifact is a frequency-specific problem that affects a particular frequency in Fourier space and produces a single vertical stripe on the image. This phenomenon occurs at a single point in time, showing a dot in k-space. The question is how this frequency-specific problem can produce a single vertical stripe on the image, instead of affecting the entire image as in the herringbone artifact. This is because the information in k-space affects the whole reconstructed image after performing a reverse FFT. The
  • #1
member 664596
TL;DR Summary
The presence of a stripe of artifact on the final MRI image would logically entail multiple points of frequency information on the actual (Fourier space) data acquisition; however, a zipper artifact is the result of a systematic corruption of a specific frequency. Why wouldn't it, then, manifest itself throughout the entire final image, as opposed to a single vertical stripe?
he so-called [herringbone or spike MRI artifact][1] on a given example could be traced to a specific point(s) in Fourier space ("k-space").

The idea is that during the acquisition of the image, a certain RF wave emitted by the patient (providing the info about diseased or normal anatomy) had become distorted by some extraneous RF interference, and sampled as such through a DFT process into Fourier space (k space). After producing the reverse FFT, that dot of artifact affected the whole image in a striped pattern:

sUbsh.png


There is another RF-interference artifact in MRI, called [zipper-artifact][3], manifested on the clinical images is as a thin stripe up and down:

EzWjA.png


In the case of the zipper artifact there is a corruption of the signal sent back to the RF antenna from the patient being scanned, affecting a particular, specific frequency, which logically matches the polluting source. This frequency-specific phenomenon would affect each signal collected in the process of filling in k space. In contradistinction, a zipper artifact occurs at a single point in time, showing a dot in k-space.

The question is:

If every point of information in k-space (Fourier space) in MRI affects the entire reconstructed image after performing a reverse FFT, how can a frequency-specific problem in Fourier space produce a single vertical stripe on image space - as opposed to affecting the whole image as in the herringbone artifact above?
 
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  • #2
What do you get when you take the FFT of a single frequency?
 
  • #3
Dale said:
What do you get when you take the FFT of a single frequency?
Are you referring to a single point in 2D Fourier space? That would yield a stripped pattern on image space. But I know you are most likely not making reference to this.
 
  • #4
Are you referring to a single point in 2D Fourier space?
No, I am asking for what you get when you transform a pure sin wave.
 
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  • #5
member 664596 said:
[text removed] In the case of the zipper artifact there is a corruption of the signal sent back to the RF antenna from the patient being scanned, affecting a particular, specific frequency, which logically matches the polluting source. This frequency-specific phenomenon would affect each signal collected in the process of filling in k space. In contradistinction, a zipper artifact occurs at a single point in time, showing a dot in k-space.

The question is:

If every point of information in k-space (Fourier space) in MRI affects the entire reconstructed image after performing a reverse FFT, how can a frequency-specific problem in Fourier space produce a single vertical stripe on image space - as opposed to affecting the whole image as in the herringbone artifact above?

Were the patients in the herringbone and zipper artifact examples enclosed in a Faraday cage during imaging?
 

1. What is a zipper MRI artifact?

A zipper MRI artifact is a type of image distortion that appears as a series of parallel lines on an MRI scan. It is caused by the metal zipper on a patient's clothing or medical equipment, such as a hospital gown or IV pole, interfering with the magnetic field of the MRI machine.

2. Why is it important to limit the zipper MRI artifact to a single line?

Limiting the zipper MRI artifact to a single line is important because it can obscure important anatomical structures and make it difficult to interpret the MRI scan. It can also lead to misdiagnosis and potentially affect patient care.

3. How can a zipper MRI artifact be limited to a single line?

One way to limit the zipper MRI artifact to a single line is by using a technique called "zipping". This involves having the patient hold their breath and move the zipper up or down during the scan, which creates a single line instead of multiple lines. Additionally, using non-metallic zippers or removing clothing with metal zippers can also help limit the artifact.

4. Can a zipper MRI artifact be completely eliminated?

Unfortunately, it is not possible to completely eliminate a zipper MRI artifact. However, by using the techniques mentioned above, it can be minimized and limited to a single line, which can greatly improve the quality and accuracy of the MRI scan.

5. Are there any other types of artifacts that can occur during an MRI scan?

Yes, there are several other types of artifacts that can occur during an MRI scan, including motion artifacts, aliasing artifacts, and susceptibility artifacts. These can also affect the quality and accuracy of the MRI image and steps should be taken to minimize them, such as having the patient remain still and using appropriate imaging parameters.

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