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| Result: Searchterm 'Echo Train'
found in 5 messages |
| Result Pages: [1] |
More Results:  Database (19) News Service (1) |
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Steve Chaloner
Thu. 3 Nov.11,
22:22
[Start of:
'GE FRFSE echo train length'
1 Reply]
 Category:
Sequences and Imaging Parameters
|
| GE FRFSE echo train length |
I've been told that when using FRFSE the ETL should be an odd number. Is this true and if so why? Thanks.
|
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(login or register first) | |
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
|
| 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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David Brooks
Tue. 22 Dec.09,
02:35
[Start of:
'Scan equation I don't get, HELP'
2 Replies]
Category:
Basics and Physics
|
| Scan equation I don't get, HELP |
Here's the question:
The approximate scan time of a rapid spin echo sequence with a TR of 3500ms, a TE of 90ms, a 256x256 matrix, 1 exicitation, a 220mm FOV and an echo train length of 5 is______ minutes.
Formal they give is 3500msx1x256/5=?
a.3
b. 8
c. 11
d. 15
I get 179200. What am I missing in my studies and the math?
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Scott Lytle
Thu. 4 Jan.07,
17:52
[Reply (2 of 3) to:
'ETL for a STIR'
started by: 'Shaun Schofield'
on Thu. 30 Mar.06]
Category:
Sequences and Imaging Parameters
|
| ETL for a STIR |
It depends.
When Centric echo allocation is used you have higher SNR, a low TE, but more image blurring. Very similar to a PD. I prefer an echo train of less than 8 in this case.
When Sequential echo allocation is used you have lower SNR, a higher TE (I prefer less than a TE of 60), but significantly less image blurring. Very similar to a T2 or FLAIR. In this case your echo train length is governed by your TE and image blurring is not usually an issue. Depending on how short of an inter-echo time you can use, and by keeping an eye on the TE, the echo train can be as high as you want.
Hope this helps.
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Michael Oliver
Sat. 27 May.06,
12:54
[Reply (1 of 3) to:
'ETL for a STIR'
started by: 'Shaun Schofield'
on Thu. 30 Mar.06]
Category:
Sequences and Imaging Parameters
|
| ETL for a STIR |
I prefer a range from 5-12 (but using shorter TE and TR). High echo trains can lead to blurring, image noise and contrast inhomogeneities.
Parallel imaging can reduce the longer scan time of low ETLs; also often 1 NSA is enough for sufficient SNR.
Hope this helps!
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