02-26-2017, 10:51 PM
Hi,
After reading the questions/answers about making an image and also viewing the videos of Prof. Paul Callaghan (referenced in this site) I'm a bit confused on how to interpret frequency encoding.
1) On the one hand, it seems that reading a single while applying the gradient along the x-axis (the frequency encoding axis) should give us the x positions (from their linear relation to the precession frequency). So a FT on the acquired signal (a line in the k-space) should give us the positions.
2) On the other hand, while acquiring the said signal, the phase unwind/rewind like a helix so the different frequencies in the acquired signal relate to the distance between full turns of the phase helix
When we interpret the results of the FT on a k-space line, do we get frequencies that correspond to the absolute position (option 1 above) or the distance between phase turns (options 2)?
How can I make sense of this?
Thank you
After reading the questions/answers about making an image and also viewing the videos of Prof. Paul Callaghan (referenced in this site) I'm a bit confused on how to interpret frequency encoding.
1) On the one hand, it seems that reading a single while applying the gradient along the x-axis (the frequency encoding axis) should give us the x positions (from their linear relation to the precession frequency). So a FT on the acquired signal (a line in the k-space) should give us the positions.
2) On the other hand, while acquiring the said signal, the phase unwind/rewind like a helix so the different frequencies in the acquired signal relate to the distance between full turns of the phase helix
When we interpret the results of the FT on a k-space line, do we get frequencies that correspond to the absolute position (option 1 above) or the distance between phase turns (options 2)?
How can I make sense of this?
Thank you