Understanding Aliasing Artifact in Medical Imaging

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Which artifact occurs when anatomy outside the FOV is folded onto the top of anatomy inside the FOV?

Appearance Aliasing (correct)

Signal distortion

Frequency wrap

Phase wrap

What causes appearance aliasing?

Undersampling of data

Frequency encoding

Signal distortion

Gradients (correct)

What is the term for aliasing along the frequency encoding axis?

Signal distortion

Frequency wrap (correct)

Appearance Aliasing

Phase wrap

What happens when the FOV is smaller than the anatomy in the frequency direction of the image?

Frequencies outside the FOV are represented as a lower frequency Signup and view all the answers

What is the term for aliasing along the phase axis of the image?

Phase wrap Signup and view all the answers

What causes phase wrap?

Undersampling of data Signup and view all the answers

What happens when the FOV in the phase encoding axis is smaller than the dimensions of the abdomen?

Phase wrap occurs Signup and view all the answers

What frequencies are accurately digitized in the FOV?

All frequencies within the FOV Signup and view all the answers

What happens to frequencies outside the FOV that exceed the Nyquist frequency?

They are represented as a lower frequency Signup and view all the answers

What is the term for the artifact where anatomy outside the FOV is folded onto the top of anatomy inside the FOV?

Appearance Aliasing Signup and view all the answers

Which technique is used to eliminate aliasing in the frequency direction?

Increasing the digital sampling rate Signup and view all the answers

What is the purpose of using presaturation bands?

To null signal from areas outside the FOV Signup and view all the answers

What is the term used to describe antialiasing along the phase axis?

No phase wrap Signup and view all the answers

How does increasing the number of phase encodings steps compensate for aliasing along the phase axis?

By increasing the number of k-space lines Signup and view all the answers

What can happen if the volume imaging does not include all of the anatomy lying outside the region under investigation?

Aliasing will occur in the slice-select direction Signup and view all the answers

How is aliasing in the frequency direction eliminated?

Increasing the digital sampling rate Signup and view all the answers

What is the effect of enlarging the FOV to compensate for aliasing along the phase axis?

It increases the scan time Signup and view all the answers

What is the purpose of antialiasing software methods?

To reduce aliasing along the phase axis Signup and view all the answers

What is the term used to describe aliasing along both the frequency and phase axes?

Remedy Aliasing Signup and view all the answers

What happens when aliasing occurs in the slice-select direction in volume imaging?

Undersampling during the process Signup and view all the answers

Understanding Aliasing Artifact in Medical Imaging

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Questions and Answers

Which artifact occurs when anatomy outside the FOV is folded onto the top of anatomy inside the FOV?

What causes appearance aliasing?

What is the term for aliasing along the frequency encoding axis?

What happens when the FOV is smaller than the anatomy in the frequency direction of the image?

What is the term for aliasing along the phase axis of the image?

What causes phase wrap?

What happens when the FOV in the phase encoding axis is smaller than the dimensions of the abdomen?

What frequencies are accurately digitized in the FOV?

What happens to frequencies outside the FOV that exceed the Nyquist frequency?

What is the term for the artifact where anatomy outside the FOV is folded onto the top of anatomy inside the FOV?

Which technique is used to eliminate aliasing in the frequency direction?

What is the purpose of using presaturation bands?

What is the term used to describe antialiasing along the phase axis?

How does increasing the number of phase encodings steps compensate for aliasing along the phase axis?

What can happen if the volume imaging does not include all of the anatomy lying outside the region under investigation?

How is aliasing in the frequency direction eliminated?

What is the effect of enlarging the FOV to compensate for aliasing along the phase axis?

What is the purpose of antialiasing software methods?

What is the term used to describe aliasing along both the frequency and phase axes?

What happens when aliasing occurs in the slice-select direction in volume imaging?

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