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| Result: Searchterm 'signal'
found in 52 messages |
| Result Pages: 1 2 3 4 5 6 7 8 [9] 10 11 |
More Results:  Database (369) News Service (50) Resources (8) |
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Mike Parks
Fri. 6 Apr.07,
18:53
[Start of:
'Need Help'
0 Reply]
 Category:
Applications and Examinations
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| Need Help |
I had an MRI yesterday and I have alot of metal in my neck due to extensive surgery such as anterior fusion from c4 to c7. Yesterdays results indicate I have atrophy of the spinal cord from C4-5 to C7 with a thin cord and high signal compatible with myelomalacia. Herniation of C3-$ that compresses the spinal cord. Central protrusion of the C2-3 and C7-T1 discs. My question is. My neck burns as if on fire inside. Is this something that will go away? I have and do have severe pain 24/7 but I've never had this kind of pain. If possible please email me at oceansmove07@aol.com if you know what's happening. Thank you for any help you may have and I wish everyone a lighter today, a brighter tomorrow and a future filled with joy and happiness.
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Johan J
Tue. 20 Mar.07,
15:55
[Reply (1 of 2) to:
'fluid PD vs T2 weighting'
started by: 'Reader Mail'
on Tue. 6 Mar.07]
Category:
Sequences and Imaging Parameters
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| fluid PD vs T2 weighting |
The truth is basicley that different tissues have different relaxation times, the signal of fluid last longer than fat in a T2, so it appears bright.
But also with a "short" TE of 30ms you can already achieve a high signal of fluid, but this is highley dependend of the TR. A long TR - 5000ms - will give you a high signal of fluid. But scantimes won't be acceptable...
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Reader Mail
Tue. 6 Mar.07,
22:48
[Start of:
'fluid PD vs T2 weighting'
1 Reply]
Category:
Sequences and Imaging Parameters
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| fluid PD vs T2 weighting |
Can anyone explain me, why - considering SE sequences with the same TR - fluid in a PD weighting (short TE) should have less signal than in a T2 weighting (long TE)? eg:
Fig 10, p 1397; radiographics resident tutorial: contrast mechanisms in spin echo MR imaging; Radiographics 1994; 14; pp 1389-1404
I would expect that the signal intensity of any tissue (regardless of it Proton density of T2-relaxation time) should decrease with increasing echo time.
Thank you
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peter hobden
Wed. 14 Feb.07,
15:35
[Reply (1 of 3) to:
'Geometric distortion'
started by: 'ergun ahunbay'
on Tue. 2 Jan.07]
Category:
Artifacts
|
| Geometric distortion |
Dear Listers,
I have some questions about the image distortions in MRI:
1) Are the magnetic field inhomogeneities the only cause of image distortions? Does RF-inhomogeneities cause distortions or just signal inaccuracies?
There are other factors that can affect the /amount/ of distortion. Run an EPI sequence and change the bandwidth and see the image change shape.
There are other causes of image distortion which are not necessarily directly related to field homogeneity.
It is a complicated question you are asking here!
2) Is it accurate to say that a spiral sequence would not have distortion due to magnetic field inhomogeneity(, but it would have blurring). Would there be image geometric distortions with a spiral imaging?
I guess you are talking about spiral filling of k-space?? The sampling time reduction will help to reduce distortion to some extent.
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Tian Ming
Mon. 22 Jan.07,
10:23
[Start of:
'MRI Marker'
1 Reply]
Category:
Applications and Examinations
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| MRI Marker |
Are there any MRI markers that are visible on all sequences, small, flat, cheap and self-adhesive?
Vitamin E or fish oil capsules work mostly well, but the signal is suppressed on sequences with fat saturation.
To mark a small region they are too big and
dent the skin where fixed.
Thankful for every suggestion and friendly greetings to all.
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