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| Result: Searchterm 'Phase'
found in 33 messages |
| Result Pages: 1 [2] 3 4 5 6 7 |
More Results:  Database (285) News Service (25) Resources (11) |
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阿立 王
Mon. 12 May.08,
08:14
[Start of:
'the phase effect of grads pulse'
0 Reply]
 Category:
Basics and Physics
|
| the phase effect of grads pulse |
hello ,everyong.I am a student from china,and recently I am writting a paper about above subject,but i can not found more resources.
who can help me?
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Herbert Müller
Thu. 5 May.22,
01:33
[Reply (11 of 12) to:
'90 excitation pulse vs 180 inversion pulse'
started by: 'Bjorn Redfors'
on Sat. 27 Jun.09]
Category:
Basics and Physics
|
| 90 excitation pulse vs 180 inversion pulse |
Hello,
I dont know if anyone has, for him/herself, answered this question. I know it is an old thread. But this is the question which also botheres me the most in NMR/MRI.
I refer now to a picture, which is illustrated in the book from Tim Claridge (High resolution NMR techniques).
Here, a RF pulse (lets say a 90 degree pulse) is said to have two effects on the initial z-magnetisation. First, it allows energy transfer between the two Zeeman-states in a way, that i equalizes the population difference between them. So there is no z- magnetisation anymore after 90 degree pulse. Th esecond effect is, that it induces phase-coherence. And this phase coherence is then responsible for the x-magnetisation, which is measured.
And now I have the same question. Why is this phase coherence lost (or is it not?), when applying an initial 180-degree pulse. Understandable for me is, why the population difference in z is reversed, but I dont understand, why there is no xy magnetisation anymore.
Maybe some of you have figured out the answer in the meantime?
Greetings
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kulas diana
Fri. 28 Apr.17,
14:59
[Start of:
'C.spine ACR protocol for Aries II'
0 Reply]
Category:
General
|
| C.spine ACR protocol for Aries II |
Im having difficulty producing a good quality exam to pass ACR accreditation for Aries II .3T open.
can someone give me any tips pls.
specially the
T2 sag
Slice thickness must be <3.0mm
GAP< 1.0mm
In plane pixel(read)<1mm
In plane pixel(phase)<1mm
Pixel are<1
I Cant get it in specs. without going over this numbers
thanks in advance
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Desiree Dupuy
Sat. 3 Dec.16,
22:14
[Reply (2 of 3) to:
'Muscle shading in 3T Images'
started by: 'Travis Conley'
on Thu. 21 Oct.10]
Category:
Applications and Examinations
|
| Muscle shading in 3T Images |
Try running a B1 Map followed by Calibration. Set RF Drive mode to Optimized. This is supposed to optimize for your Patient. Supposed to reduce dielectric effect/shading for Lumbar and Abdomen.
You can find under GE Additional Abdomen Sequences.
Or you can run Ideal with Dixon technique. Turn on IN phase will give you T1 FS & IN Phase is you plane T1. I believe this takes care of the artifact.
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Cristobal Bertoglio
Mon. 1 Aug.16,
21:59
[Start of:
'PCMRI'
0 Reply]
Category:
General
|
| PCMRI |
Hi everybody
I am curious to understand a bit better what the formula that it is used in PCMRI for relating the change of phase and the velocity assume ...
As far I have unterstand that it is assumed the phase of a moving particle can be measured at two time instants, i am right? Does this not assume we can "track" the particle? Does this not "contradict" the fact that we can only compare phases that we measure at the same fixed place?
Thanks,
C.
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