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| Result: Searchterm 'K-Space'
found in 13 messages |
| Result Pages: 1 [2] 3 |
More Results:  Database (65) News Service (1) Resources (2) |
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Behrouz Rahimpour
Sun. 17 Oct.10,
05:31
[Reply (1 of 2) to:
'How to fill the K-space?'
started by: 'Leak Sea'
on Sat. 16 Oct.10]
 Category:
Basics and Physics
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| How to fill the K-space? |
Is your question regarding k-Space filling patterns?
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|  View the whole thread | | |
Adrian Roman
Sat. 26 Dec.09,
13:26
[Start of:
'MRI data before 2D FFT'
0 Reply]
Category:
Basics and Physics
|
| MRI data before 2D FFT |
Hi,
I need some raw data in k-space, that is, before applying 2D FFT on it. I want to implement a program that does the transfrom, in order to exemplify the process. Is there such thing available?
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peter hobden
Wed. 14 Feb.07,
15:35
[Reply (1 of 3) to:
'Geometric distortion'
started by: 'ergun ahunbay'
on Tue. 2 Jan.07]
Category:
Artifacts
|
| Geometric distortion |
Dear Listers,
I have some questions about the image distortions in MRI:
1) Are the magnetic field inhomogeneities the only cause of image distortions? Does RF-inhomogeneities cause distortions or just signal inaccuracies?
There are other factors that can affect the /amount/ of distortion. Run an EPI sequence and change the bandwidth and see the image change shape.
There are other causes of image distortion which are not necessarily directly related to field homogeneity.
It is a complicated question you are asking here!
2) Is it accurate to say that a spiral sequence would not have distortion due to magnetic field inhomogeneity(, but it would have blurring). Would there be image geometric distortions with a spiral imaging?
I guess you are talking about spiral filling of k-space?? The sampling time reduction will help to reduce distortion to some extent.
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Renate Bloemer
Mon. 13 Nov.06,
19:46
[Reply (1 of 3) to:
'MRA'
started by: 'Marco Costa'
on Sun. 22 Oct.06]
Category:
Protocols
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| MRA |
A test bolus helps to get the delay at which time the CE-MRA sequence has to be started. The sequence needed is a one-slice dynamic fast gradient echo sequence (if possible with fat suppression or subtraction) and a temporal resolution of 0.5 to 1.5 sec. This thick slice is placed over the vessel of interest and the dynamic is started simultaneous with a small (1-2ml) bolus of Gad.
In the follow up you can see at which time the bolus is visible. If it is not clear to differentiate, a ROI measurement will help. The starting time depends on the k-space filling. Around the peak of the highest intensity, the contrast information should be read out (with "centric" at the beginning of the sequence).
Centric k-space filling order means that the central lines of the k-space are filled in the first seconds after starting the scan. Depending on the equipment, there is more than one non-centric order, for example linear, where the central lines are filled in the middle of the scan time.
Hope this helps.
Renate Bloemer
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| | View the whole thread | | |
Renate Bloemer
Mon. 13 Nov.06,
19:35
[Reply (1 of 3) to:
'Receiver Bandwidth'
started by: 'Stephanie Taylor'
on Wed. 1 Nov.06]
Category:
Basics and Physics
|
| Receiver Bandwidth |
Maybe these links will help: http://www.revisemri.com/tutorials/receiver_bandwidth/rbandwidth_files/fullscreen.htm
http://www.medical.siemens.com/siemens/en_US/rg_marcom_FBAs/files/DICpage/MRIHottopics2.pdf
http://www.ebyte.it/library/educards/mri/K-SpaceMRI.html
http://www.mr-tip.com/serv1.php?type=db1&dbs=Bandwidth
Renate Bloemer
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