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| Result: Searchterm 'Echo'
found in 43 messages |
| Result Pages: 1 2 3 4 5 6 [7] 8 9 |
More Results:  Database (305) News Service (7) Resources (10) |
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Reader Mail
Sun. 27 Jan.08,
08:47
[Start of:
'Plz Answer this ... Contrast MRI of Brain'
1 Reply]
 Category:
Applications and Examinations
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| Plz Answer this ... Contrast MRI of Brain |
Pre and Post contrast mri of the brain was performed in multiple planes using T1 & T2 W spin-echo sequence.
There is small ring enhancing lesion in the left occipitoparietal lobe which measures 1cm in diameter.It reveals isointense periphery on T1 & T2W images with hyperintense core on T2W images. On T1W images the core appears hypointense . A tiny mural nodule is seen within the lesion. focal perilesional edema is seen appearing hyperintense on FLAIR and T2W images.
The brainstem & cerebellum are normal.
The ventricular system is normal.
No abnormal meningeal enhancement is seen.
Intracranial vessels display normal flow void.
What needs to be done?? How serious the problem is??
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Jenny Jordan
Sat. 17 Nov.07,
20:11
[Reply (2 of 4) to:
'Haste and Rare sequences'
started by: 'Elena sussi'
on Tue. 13 Nov.07]
Category:
Sequences and Imaging Parameters
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| Haste and Rare sequences |
Hi Elena,
you can find the different names for the same sequences and options used by manufacturers at: http://www.mr-tip.com/serv1.php?type=cam .
The manufacturers have in principle similar sequences with small differences. So, as you mentioned you can take "sequences as HASTE" or "sequences type RARE".
However, you can lead back these sequences also to the fundamental sequence type FSE ( fast spin echo: http://www.mr-tip.com/serv1.php?type=seq&sub=12 ). Fast sequences as HASTE ( http://www.mr-tip.com/serv1.php?type=db1&dbs=haste ) are especially useful in cases of movement caused by their single shot technique: http://www.mr-tip.com/serv1.php?type=db1&dbs=Single%20Shot%20Technique .
Hope this helps
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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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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
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| 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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Renate Bloemer
Mon. 13 Nov.06,
19:46
[Reply (1 of 3) to:
'MRA'
started by: 'Marco Costa'
on Sun. 22 Oct.06]
Category:
Protocols
|
| MRA |
A test bolus helps to get the delay at which time the CE-MRA sequence has to be started. The sequence needed is a one-slice dynamic fast gradient echo sequence (if possible with fat suppression or subtraction) and a temporal resolution of 0.5 to 1.5 sec. This thick slice is placed over the vessel of interest and the dynamic is started simultaneous with a small (1-2ml) bolus of Gad.
In the follow up you can see at which time the bolus is visible. If it is not clear to differentiate, a ROI measurement will help. The starting time depends on the k-space filling. Around the peak of the highest intensity, the contrast information should be read out (with "centric" at the beginning of the sequence).
Centric k-space filling order means that the central lines of the k-space are filled in the first seconds after starting the scan. Depending on the equipment, there is more than one non-centric order, for example linear, where the central lines are filled in the middle of the scan time.
Hope this helps.
Renate Bloemer
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