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| Result: Searchterm 'Signa'
found in 79 messages |
| Result Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 [15] 16 |
More Results:  Database (382) News Service (60) Resources (16) |
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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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David Jennions
Tue. 18 Jul.06,
10:46
[Start of:
'1.5T field contours'
0 Reply]
Category:
Devices, Scanner, Machines
|
| 1.5T field contours |
Greetings!
I'm testing simultaneous MR and optical imaging, and need to calculate the MR field strength along the bore axis of a GE Signa HDe 1.5T. Any online references / other data that folks can point me at would be most appreciated!
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miri leh
Sun. 15 Jan.06,
16:28
[Start of:
'Upright MRA'
1 Reply]
Category:
Applications and Examinations
|
| Upright MRA |
Device question: is there a device that enables MRA in an upright position with head bending?
(I'm asking this after I was disappointed to discover this was impossible in the GE Signa TM SP/i System)
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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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tina muthana
Thu. 14 Apr.05,
22:44
[Start of:
'diffusion MRi'
1 Reply]
Category:
Basics and Physics
|
| diffusion MRi |
Hi
My name is Tina and I am currently studying Diffusion weighted MRI. I was wondering if anyone could elaborate on the effect of introducing a slice selection gradient along with the diffusion gradient on the signal attenuation. Also if there are any sites that could explain it, I would appreciate the information.
Thank you.
-TIna
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