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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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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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GONZALO SOLIS
Tue. 22 Nov.05,
05:35
[Start of:
'usmarine2tim2'
0 Reply]
Category:
Basics and Physics
|
| usmarine2tim2 |
Hello to all my fellow MR Technologists and / or students:
I have a few questions that I would greatly appreciate if someone could help me answer. The dead line is THIS Friday 25th 1000AM morning so please reply STAT
Please e mail me at USMARINE2TIM2@YAHOO.COM
1. . Breath hold duration of less than _________are
recommended when dealing with MR Arenal artery
scan?
a. 30sec
b. 25sec
c. 18sec
d. 8
2. . In renal angiography, what anatomical
landmark does the 3d slab need to cover just
anterior to?
a. Adrenal glands
b. Hepatic vein
c. Portal vein
d. Abdominal aorta
3. .What makes MRI a better choice than DSA for evaluation of a bilateral renal artery stenoses at the orgins of the renal arteries?
a. It is a noisier examination
b. The contrast used is less nephrotoxic than DSA
contrast
c. MRI has higher special resolution than DSA
4. Signal loss will result when further maturation of the clot produces which one of the following?
a. methemoglobin
b. hemosiderin
c. phagocytosis.
d. hemoglobin
5. .For cine gradient echo imaging with true FISP, which of the following statements is TRUE?
a. .images have better image contrast and acquisitions are faster than conventional cine gradient echo imaging
b. cine true FISP images can be performed on any MRI unit
c. to make true FISD images, intravenous gadolinium contrast is needed
d. .true FISP images cannot be used for breath- hold acquisitions because the sequence is too slow
6. Which one of the following statements is NOT
true about phase contrast imaging?
a. .phase contrast imaging is useful for measuring blood flow
b. .phase contrast images are ECG gated
c. .phase contrast images can be performed on most
scanners with cardiac imaging capabilities
d. phase contrast images required
intravenous gadolinium contrast
Thank you so much
Gonzalo RT (R) --future-Ã MR
God Bless
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Nancy Dudek
Fri. 26 Aug.05,
00:25
[Start of:
'3T imaging parameters'
2 Replies]
Category:
Sequences and Imaging Parameters
|
| 3T imaging parameters |
Hi
Am looking for the ranges of acceptable TR and TE's for standard spin echo and gradient echo sequences on a 3T.
Does anyone know these or tell me where I can find this info?
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Schmidt Marga
Sat. 17 Apr.04,
20:41
[Reply (1 of 2) to:
'Moire fringing'
started by: 'Kelly Wimpey'
on Tue. 6 Apr.04]
Category:
Artifacts
|
| Moire fringing |
Moire fringes are typical for gradient echo sequences, especially balanced sequences like for example true fisp, bFFE. The reasons are interferences and field inhomogeneities. High order shimming (volume shimming), a more suitable coil, a smaller bandwidth, and scanning not in the edges of the magnetic field will avoid or reduce this artifact. Also parallel imaging techniques can have a positive influence. If this artifact appears, also by using other sequences, a new field adjustment can be necessary (service).
Hope this will help.
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