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'Pixel'
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Result: Searchterm 'Pixel' found in 8 messages
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Pim vanOoij

Thu. 19 Mar.09,
09:58

[Reply (2 of 3) to:
'PCA aliasing problem'
started by: 'Pim vanOoij'
on Fri. 27 Feb.09]


 
  Category: 
Artifacts

 
PCA aliasing problem
This is not spatial aliasing I am talking about, but velocity aliasing. This means that when your velocity encoding parameter is set to 100 cm/s and true velocity in a certain pixel is 120 cm/s, the measured velocity will be -80 cm/s.

In my problem however, with a velocity encoding parameter of 100 cm/s, in certain pixels I measure a velocity of around -60 cm/s where an actual velocity of 40 cm/s exists, which is a real mystery to me.

I don't think increasing FOV will prevent this from happening. Maybe it has something to do with velocity aliasing in other parts of the FOV, where true flow velocity of 110-120 cm/s exists, but I wouldn't know why. Anyone? Thanks.
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Pim vanOoij

Fri. 27 Feb.09,
15:27

[Start of:
'PCA aliasing problem'
2 Replies]


 
  Category: 
Artifacts

 
PCA aliasing problem
Hi everyone,

Has anybody who reads this ever encountered aliasing in phase contrast measurements in pixels where velocity did not exceed Venc? If so, could this be due to signal leakage of surrounding vessels? Thanks for your help!

Pim
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Johan J

Thu. 8 Feb.07,
20:48

[Reply (2 of 3) to:
'scan matrices and steps'
started by: 'Steven Smith'
on Wed. 20 Dec.06]


 
  Category: 
General

 
scan matrices and steps
It means that the matrix is variable, so you can choose to have 256, 260, 264 etc matrixes. This is than again part of how advanced the fourier transformation algorithm is.

Cheers

BTW Matrixes are just a number, and actually say nothing at all regarding resolution...yess FOV devided by matrix gives you a pixel size which is actually the interesting part.
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