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| Result: Searchterm 'Phase'
found in 33 messages |
| Result Pages: 1 2 3 4 5 [6] 7 |
More Results:  Database (285) News Service (25) Resources (11) |
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Neeta Vyas
Tue. 9 Sep.08,
00:46
[Start of:
'flow arifact'
1 Reply]
 Category:
Artifacts
|
| flow arifact |
Hi Everyone,
I had experienced flow artifact while taking Axial images of a wrist on 1.5T Siemens MRI scanner. I was using a presaturation band to block the arterial blood flow but it was not making any difference and the artifact was still there.
The phase direction was A-P, and the artifact was in this direction.
Please help me to get rid of this artifact.
Neeta
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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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Reader Mail
Sun. 19 Feb.06,
14:36
[Start of:
'CE-MRA Vasovist protocol'
1 Reply]
Category:
Protocols
|
| CE-MRA Vasovist protocol |
We will start soon with Vasovist (MS-325) for peripheral CE-MRA with moving table. Expecting higher resolution due to longer possible scan times - but discussing timing and needed post processing.
Is bolus timing needed - is fluoroscopic triggering possible - for the arterial phase?
Any experiences with this contrast agent, a good scan protocol or some good sources about Vasovist?
Anything appreciated!
Greetings
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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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Emil Cohen
Sat. 19 Mar.05,
01:03
[Reply (3 of 4) to:
'CE MRA of the Liver'
started by: 'bob mitchell'
on Sun. 5 Dec.04]
Category:
Applications and Examinations
|
| CE MRA of the Liver |
The above statements are correct, also remember that the portal vein is brightest in the first pass of contrast through it so having a short sequence for the arterial phase <20 seconds and going straight into the portal phase is important(ie one inspiration/expiration only between repeating the sequence). The portal vein will become brightest within 30 seconds of the artery.
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