MR Physics 4 - K Space

Audience: Radiology Residents
Summary:
K-space is symmetrical
The center provides contrast information
The periphery provides spatial resolution
Radial K-space filling reduces artifact due to gross motion
Credit to MRI Principles. Mitchell and Cohen. Saunders 2nd Ed, Dec 5, 2003
for select images.

[@BradCaldwellAuburn]

Thank you! First video on k-space that actually explained its coordinate system.

[@meohash1]

well explained - watched two videos before this one and this truely made more sense ...thank you

[@RadiologyEducation]

I work hard to distill it down. May oversimplify at times, but a deep understanding of kspace is very hard to achieve

[@MuhammadSulemankmc]

Thanks for the video. if each value in K-space represents a different voxel in the slice, then removing the peripheral part of the k-space should remove the peripheral part of the image. however in reality it only loses fine details. this makes me more confused.

[@jacobvandijk6525]

No, there is no 1-on-1 relationship between a point in k-space and a point in image-space. Each value in k-space is related to EVERY POINT in image-space. So removing a point in k-space influences the entire image! Fine details are related to small wave lengths. At the edges of k-space the k-value is largest! Because k = 1 / wave length, removing a high k-value = removing a small wave length = removing some fine detail all over the image.

[@BradCaldwellAuburn]

Removing one point from k-space affects every pixel on ultimate brain image.

[@fedfamily4005]

I think you have resolution and FOV reversed at circa 8:00 minutes. Resolution is always considered element per distance and FOV is simply distance. In other words, resolution is how many voxels per distance of k-space. I think the bottom k-space is supposed to say "Same resolution, 1/2 FOV" and the right k-space should say "Lower resolution, Same FOV". IMHO

[@BradCaldwellAuburn]

I think video is correct because resolution and Fov is about the image you're going to convert to ultimately (the resolution/fov of brain image to be generated).

[@immane75]

please explain the matrix , FOV .........

[@sladpooja4218]

Yes plzz

[@dlo5640]

Couldnt the center of k space also be 0 phase 0 frequency? and the frequency doing the same thing as phase making it go from 7 to 0 to -7? So the center would have no gradient

[@Milagrosblanco684]

I'm currently enrolled in an MRI program and I am having MAJOR regret! All of this is extremely boring and difficult for the instructor to explain himself. This is only the beginning but I HOPE the other courses are more interesting......