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| Result: Searchterm 'Gradient Echo'
found in 9 messages |
| Result Pages: [1] 2 |
More Results:  Database (121) News Service (1) Resources (2) |
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Steven Ford
Fri. 26 Oct.18,
02:29
[Reply (1 of 2) to:
'When to shim?'
started by: 'Matt H'
on Fri. 27 Oct.17]
 Category:
General
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| When to shim? |
you ask a complex question. Any sequence that is not a standard spin echo can benefit from shimming, but its not always worth it.
If you are scanning a knee in the center of the magnet, or nearly so, you might not see much difference in gradient echo scans, which in general are quite sensitive to shim problems. But if you are doing fat-water separation or fatsat images, you will see a difference even in this example.
Because hardware varies, its hard to say in one blanket statement for every case. For sure, do it on fatsat or fat-water imaging. The next most sensitive studies are off-center imaging such as shoulders. Beyond that, you should experiment a little. Of course, erring on the side of caution is a good idea.
Steven Ford
Professional Imaging Services, Inc.
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|  View the whole thread | | | |
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John Smith
Wed. 11 Nov.15,
22:14
[Start of:
'Faster pulse sequences'
0 Reply]
Category:
General
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| Faster pulse sequences |
Hi,
I have been learning about faster MRI sequences and have two questions
1) With "Fast (Turbo) gradient echo", in which we apply a spoiler gradient, do we not eventually end up with no longitudinal magnetization because TR is always shorter than T1? Hence shouldn't we eventually get no signal at all?
2) in SSFP (Steady-state free precession) we can apply an RF pulse of 90 degrees (in which T1>>T2) to get heart-blood contrast. How is this any different to a standard spin-echo sequence in terms of timing?
Thank you
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aaron yonts`
Thu. 19 Sep.13,
07:56
[Reply (1 of 3) to:
'why there is T2* but not T1*'
started by: 'Isa Toni Toni'
on Wed. 24 Jul.13]
Category:
Sequences and Imaging Parameters
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| why there is T2* but not T1* |
i may just be giving general info but a t2* is aquired from a gradient echo compared to a t2 with a spin echo. according to mri in practice a t2* can help show some things a normal t2 would not, such as ms plaques in a cervical spine
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martin chavez
Thu. 31 Jan.08,
00:59
[Reply (1 of 2) to:
'gre trauma ax'
started by: 'diana navarro'
on Tue. 29 Jan.08]
Category:
Applications and Examinations
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| gre trauma ax |
this is a t2* or gradient echo and we use this for all head trauma pt's and to look for old blood in the brain.
gre trauma ax comes from a ge protocol and thats
what ge named that sequence.
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