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| Result: Searchterm 'epi'
found in 15 messages |
| Result Pages: 1 [2] 3 |
More Results:  Database (85) News Service (35) Resources (6) |
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Jacob Newton
Thu. 7 Oct.10,
19:22
[Reply (1 of 2) to:
'How does TE affect DWI acquisition?'
started by: 'danilo Scelfo'
on Wed. 29 Sep.10]
 Category:
Sequences and Imaging Parameters
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| How does TE affect DWI acquisition? |
I never tried to shorten only the echo time while keeping all other parameters the same, but I would expect a change in SNR and artifact appearance. I would use parallel imaging methods to get a shortest possible echo time. Parallel imaging provides DWI with shorter echo trains associated with further reduction of the echo and repetition times, which reduces susceptibility effects and also image blurring. Additionally, the shorter echo time may lead to changes in ADC measurement.
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danilo Scelfo
Wed. 29 Sep.10,
12:15
[Start of:
'How does TE affect DWI acquisition?'
1 Reply]
Category:
Sequences and Imaging Parameters
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| How does TE affect DWI acquisition? |
Hi folk! Just a breath question: how does TE affect conventional sequence (single shot SE-EPI) for DWI acquisition? In particular, how would two acquisitions differ from each other if acquired with TE=90/106ms respectively (being equal all the other parameters, i.e. TR=11s, same FOV, …)? Thanks for any opinion you will give me. Danilo.
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Michiel Klitsie
Wed. 2 Jun.10,
14:53
[Start of:
'Imaging of the sacral plexus'
1 Reply]
Category:
Applications and Examinations
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| Imaging of the sacral plexus |
We are students Technical Medicine from Twente University and are researching the imaging of the anatomical variation of the sacral plexus. This means the imaging of nerves in a fatty/muscle enviroment with a diameter below 1 mm.rnrnWe are interested in different MR-sequences that will show these small nerves (at the moment we came up with MP(2)Rage, STIR, normal SE T1 and DW) Does anybody can provide us why we should or shouldn't use one of these sequences. Or maybe somebody does have a better suggestion?rnrnAlso we were planning to combine spinal and abdominal coils (phased-array RF coils), does this depict the sacral plexus in a good way?rnrnWe also thought about using a 7T MRI scanner, because of the high spatial resolution. Is this a possibility or does it give to much artifacts? Or is the spatial resolution in a 3T machine enough for such small nerves?rnrnThanks in advance!
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Sam Shelly
Sun. 2 Nov.08,
23:02
[Reply (2 of 3) to:
'Regarding recovery and decay [basic phycisc]'
started by: 'harry sanders'
on Sat. 7 Jun.08]
Category:
Basics and Physics
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| Regarding recovery and decay [basic phycisc] |
Right on.
Recovery and delay are two separate physical processes like the last guy said. It had me stumped for a while when I was studying as well. But read carefully and think hard about it...
T1 recovery is the return of net magnetization into alignment with b0.
T2 decay is a totally different process and is, as the previous person said, simply loss of net magnetization in the transverse plain due to dephasing. The more electrons that are precessing in phase in the transverse plane, the stronger the NMV is in that plane. And, hence forth, when the RF pulse terminates, the influence of b0 gradually dephases the electrons in the transverse plane. As they dephase, the transverse NMV decreases accordingly, until the next pulse hits, rephasing the electrons and starting the process all over.
Hope that helps. MRI physics is hairy and boring at times. Load up on expressos to stay awake and stick with it, because studying MRI physics can be like taking a bottle of sleeping pills.
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Reader Mail
Sun. 25 May.08,
07:07
[Start of:
'Artifacts'
2 Replies]
Category:
Artifacts
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| Artifacts |
If any one has an experience in solving a problems of radio freq and zebra strips artifacts with keeping in mind that the shilding is very good
please,tell me about your suggestions
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