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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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Jennifer Jackson
Fri. 21 Jul.06,
04:44
[Reply (1 of 2) to:
'Phase encoding'
started by: 'guillaume bierry'
on Fri. 7 Jul.06]
 Category:
General
|
| Phase encoding |
Wow this is a long subject, First you have to under stand how the 3 main gradients are used. (slice select, Freq, then phase)
So you are use 1 of the gradients for your phase encoding. You need to fill the k-space which depends on you matrix. Lets assume you are using 256 (phase). In order to fill K-space you have to have 256 aquistions of the signal. Meaning for each picture (or slice) the signal must be acquire(sampled) 256 times each at a differnt amplitude to put it in a different Line of k-space.
Example- If you are performing a SE(spin echo) you have 1 TR period and 1 TE period (TE=is when the signal is sampled) so you will have to do the TR period 256 times to fill K-space with diffent amplitudes.
There is alot more that I left out. If this did not answer your question let me know
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Michael Oliver
Sat. 27 May.06,
12:54
[Reply (1 of 3) to:
'ETL for a STIR'
started by: 'Shaun Schofield'
on Thu. 30 Mar.06]
Category:
Sequences and Imaging Parameters
|
| ETL for a STIR |
I prefer a range from 5-12 (but using shorter TE and TR). High echo trains can lead to blurring, image noise and contrast inhomogeneities.
Parallel imaging can reduce the longer scan time of low ETLs; also often 1 NSA is enough for sufficient SNR.
Hope this helps!
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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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Marilia White
Thu. 3 Mar.05,
16:40
[Start of:
'Contrast MRA COW.'
3 Replies]
Category:
Contrast Agents
|
| Contrast MRA COW. |
Just started a new job and the tech there insists on injecting with a butterfly then coming out and running a 3D MRA of the Head. Has anyone ever heard of this? I have done carotids but not Circle of willis. If there is such a thing please let me know your Protocol. I am open to any suggestions on the Carotids to. She injects them with a butterfly as well and what a mess. Help I just got back on GE echospeed after 5 yrs and no manual. Just a crazy tech. Please help.
azoreangal
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