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| Result: Searchterm 'Suppression'
found in 7 messages |
| Result Pages: 1 [2] |
More Results:  Database (49) News Service (2) Resources (2) |
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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
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| 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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William Flemming
Tue. 29 Mar.05,
02:49
[Reply (1 of 2) to:
'MR image of an eye'
started by: 'Reader Mail '
on Tue. 14 Dec.04]
Category:
Applications and Examinations
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| MR image of an eye |
Depending on the sequence and the field strength there can be artifacts that look like eye movement and are difficult to separate. To avoid eye movement should the patient not only close the eyes or fix a point, but also with closed eyes think about not to move the eyes.
Other artifacts (e.g. ghosting) can be reduced with fat suppression, reduction of the water fat shift, T1 with a long TE (to reduce the brightness of fat), and/or a higher matrix.
Also the perfect positioning of the coil and a homogeneity correction will improve the image quality. I do not know a post processing program that removes those artifacts.
Regards
Bill
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