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TOOLS
» K-Space Tool

What happens in k-space? This tool allows you to choose changes to be made to a k-space data set. The result of these changes is seen and discussed.

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K-Space Tool: High Pass Filter

The high pass filter removes the low spatial frequencies from k-space. When the fast Fourier transform is performed, the image shown is produced. It can be seen that there is little contrast in this image, yet edge definition remains. This is because the fine details of the image (edges etc.) are contained in the high spatial frequencies which are in the peripheries of k-space.

im_hpf (12K) k_hpf (4K)

Further reading on this topic:
Books: MRI From Picture to Proton p52-53, 119
Online: e-MRI

Choose from the list below alter k-space.

Alter k-space...

Introduction.
Apply a low pass filter—see only the contrast of the image.
Apply a high pass filter—see only the detail of the image.
Introduce random motion artefacts—cf coughing, swallowing, moving.
Introduce periodic motion artefacts—cf breathing, pulsatile flow.
Add random noise.
Add more random noise.
Create a large RF spike near centre of k-space.
Create a small RF spike near centre of k-space.
Create a large RF spike at the periphery of k-space.
Create a small RF spike at the periphery of k-space.
Reduce the scan percentage—miss out the top and bottom of k-space.
Acquire just over half of k-space—partial Fourier with three extra lines.
Remove every other k-space line—similar to how SENSE (sensitivity encoding) achieves accelerated data acquisition.

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TOOLS» K-Space Tool

K-Space Tool: High Pass Filter

TOOLS
» K-Space Tool