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| Result: Searchterm 'HIS'
found in 303 messages |
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More Results:  Database (430) News Service (375) Resources (57) |
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Artemiy Artemiy
Fri. 16 Mar.12,
19:54
[Start of:
'How to estimate areas of lesion on MRI in multiple sclerosis'
3 Replies]
 Category:
Applications and Examinations
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| How to estimate areas of lesion on MRI in multiple sclerosis |
Hello
I'm a neurologist from the Military medical academy at St-Petersburg in Russia. In Internet I found some articles about MS from you. I study correlation: cognitive impairments and areas of lesion by using MRI in multiple sclerosis. What the program would be better to estimate areas of lesion (total volume, topical spreading in white matter)? I'll be very glad to receive any answer. I didn't find answer to this question in Radiology department at the M-Med Academy. I tried to use SPM8, but understand, that its impossible to research volume of areal in MS. (I spent a lot of time for nothing)
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Reader Mail
Wed. 14 Mar.12,
20:50
[Start of:
'Who shims MRI systems in Uzbekistan'
3 Replies]
Category:
Equipment
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| Who shims MRI systems in Uzbekistan |
We have MRI equipment (Siemens Concerto) in our hospital and we want to do shimming of this MRI system. Please reply to this thread if you offer a shimming service in Uzbekistan.
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Tetiana Dadakova
Fri. 17 Feb.12,
10:07
[Reply (1 of 2) to:
'MR750: ASSET Artifact or 32 Channel coil?'
started by: 'Reader Mail'
on Tue. 26 Jul.11]
Category:
Funktional MRI
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| MR750: ASSET Artifact or 32 Channel coil? |
Hi,
We do have the same artifact on the same scanner with 32 channel coil. I was thinking about herringbone artifact as well first, but then some kind of "spikes" of very high or low intensity should be seen in k-space, which I don't see in our images. We have this artifact only for DTI.
If you find out what it is, please let me know.
Best regards.
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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
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| 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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Steven Ford
Tue. 31 Jan.12,
07:53
[Reply (1 of 2) to:
'IP address'
started by: 'Cathy Fick'
on Mon. 21 Nov.11]
Category:
Devices, Scanner, Machines
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| IP address |
You need the service disk for this. If your intent is to push images to another device, you also need to know the calling titile and the port number.
Steven Ford
Professional Imaging Services, Inc.
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