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| Result: Searchterm 'Array'
found in 5 messages |
| Result Pages: [1] |
More Results:  Database (61) News Service (5) Resources (4) |
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Richard Powell
Wed. 26 Nov.08,
14:58
[Start of:
'Neuro vascular array does not perform DWI'
0 Reply]
 Category:
Equipment
|
| Neuro vascular array does not perform DWI |
We recently had an software upgrade to our GE 1.5T Echospeed. The diffusion weighted imaging stopped working when using the neuro vascular array. Has any one else experienced this problem? What was done to correct the problem?
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Steven Ford
Tue. 31 Jan.12,
08:19
[Reply (1 of 2) to:
'RF shimming'
started by: 'Reader Mail'
on Thu. 1 Oct.09]
Category:
Basics and Physics
|
| RF shimming |
For Magnetic fields, the overall field is adjusted to push it up a little bit in one spot and push it down a little bit in another area. The goal is to create a field that's perfectly homogenous.
The RF field created by the transmit coil likewise must be as homogenous as possible, so that the flip angle is constant throughout the imaging volume. In the past, designers have solved this problem by building coils such as the 'birdcage' style that would create a very even amount of energy inside. This is one reason why the transmit coils tend to be large.
With the advent of 3 Tesla and stronger magnets, the RF resonant frequency also rises. RF energy absorbed in the patient rises with the higher frequencies also, and another problem raises its head: it's a lot harder to make a very homogenous RF field. Even if you are scanning phantoms, the inside tends to be subject to different energy than the edges.
But in the human body, there are all sorts of irregular lumps and bumps that absorb RF differently, further complicating matters.
Now, on modern scanners it's possible to perform a magnetic field shim with the patient actually in the magnet in order to compensate for minute changes in the magnet from one exam to another. For super-high field magnets, an RF shim is also a handy thing to do.
If you have a Multi element RF transmit coil (regular phased array coils are just for receiving) you can run a program which selectively turns up the power in some elements so that the overall signal received is maximized. That's an RF shim.
Steven Ford
Professional Imaging Services, Inc.
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Michiel Klitsie
Wed. 2 Jun.10,
14:53
[Start of:
'Imaging of the sacral plexus'
1 Reply]
Category:
Applications and Examinations
|
| Imaging of the sacral plexus |
We are students Technical Medicine from Twente University and are researching the imaging of the anatomical variation of the sacral plexus. This means the imaging of nerves in a fatty/muscle enviroment with a diameter below 1 mm.rnrnWe are interested in different MR-sequences that will show these small nerves (at the moment we came up with MP(2)Rage, STIR, normal SE T1 and DW) Does anybody can provide us why we should or shouldn't use one of these sequences. Or maybe somebody does have a better suggestion?rnrnAlso we were planning to combine spinal and abdominal coils (phased-array RF coils), does this depict the sacral plexus in a good way?rnrnWe also thought about using a 7T MRI scanner, because of the high spatial resolution. Is this a possibility or does it give to much artifacts? Or is the spatial resolution in a 3T machine enough for such small nerves?rnrnThanks in advance!
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Stuart Allison
Tue. 16 Sep.08,
12:41
[Start of:
'GE LX MRI Platform?'
3 Replies]
Category:
Devices, Scanner, Machines
|
| GE LX MRI Platform? |
I'm working to gain an understanding of MRI equipment, specifically GE equipment, and I'm kind of confused by some of the terms that I see associated with the scanners when they are being listed for sale. Can anybody give me a quick idea about what is being talked about when they are referring to the "LX Platform" on a GE MRI scanner? I think it might have some relationship to phased array channels, but I'm not sure. I have also seen references to the "5X Platform" and the "Excite Platform", are these mutually exclusive to the LX platform (updated/prior models?) Thanks in advance to anyone with some GE experience who can help out.
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Reader Mail
Sun. 2 Apr.06,
14:47
[Start of:
'Open MRI'
0 Reply]
Category:
Coils
|
| Open MRI |
What is the difference between rapid coil, multiple array and QD coil?
And which one is the best?
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