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| Result: Searchterm 'Orientation'
found in 7 messages |
| Result Pages: [1] 2 |
More Results:  Database (16) |
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Reader Mail
Thu. 2 Feb.12,
17:09
[Start of:
'Shoulder orientation'
1 Reply]
 Category:
General
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| Shoulder orientation |
Scanning orientation is Right to Left.
Why do coronal shoulder images of the left side display like right coronal shoulders if you use a steep angle?
Scanning with a steep angle on a right shoulder is not effected by a steep angle why?
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Gary Brown
Mon. 14 Jun.21,
15:20
[Start of:
'Stents'
0 Reply]
Category:
General
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| Stents |
Employer relates that any cardiac stent implanted after 2008 is safe on ANY MRI scanner within our system. This ranges from 0.3 Open scanners to 1.2 High field Open and 1.5 and 3T closed systems.
Contrarily, the manufacturer data on certain stents states 1.5 or 3 T ONLY, but we are urged to scan on an open if implanted after 2008. Does anyone have any type of testing documentation that this is safe? I'm not so much worried about the field strength as I am the magnetic field orientation as the defining safety issue.
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Math G
Fri. 30 Jun.17,
21:02
[Reply (10 of 12) to:
'90 excitation pulse vs 180 inversion pulse'
started by: 'Bjorn Redfors'
on Sat. 27 Jun.09]
Category:
Basics and Physics
|
| 90 excitation pulse vs 180 inversion pulse |
I will try an answer to this rather old tread, in case someone stumble upon this like me.
The phenomenon of "coherence" that produce transverse magnetization after a 90 RF pulse cannot be answered by classical mechanics, or any simple model that represents individual protons as precessing magnets in either the parallel/antiparallel direction with regards to the MRI magnetic field.
Rather, it is a phenomenon related to quantum mechanics and the effect of a RF field on a interacting group of particles with spins (not necessarily oriented as parallel/antiparallel, I might add, even under the effect of a magnetic field).
The simplest depiction, as I understand, would be to imagine a group of spins as literally rotating as a whole under the effect of the RF. After a certain time (corresponding to a 90 degree pulse), the net magnetization that was oriented parallel to the MRI magnetic field, is now oriented in the transverse plane, causing transverse magnetization and signal. If you further apply RF, the system will continue to rotate, shifting gradually toward an antiparralel orientation, losing transverse magnetization in the process.
Hope its clearer!
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Steven Ford
Tue. 5 Aug.14,
20:01
[Reply (1 of 2) to:
'?'
started by: 'Belinda Williams'
on Mon. 21 Jul.14]
Category:
Coils
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| ? |
Belinda,
It would be helpful if you would add a photo, even if you take a cellphone photo of your screen and blot out the name.
You did not say, but is this a new problem?
In general, if one orientation looks worse than others, you may have a magnet shim problem; you can crudely test this yourself by using a cylinder type phantom and doing an identical scan in three planes. A shim problem would affect T2's more than T1 or PD images also.
There is always a possibility that your sequences have changed without you realizing it too; check this even if you don't know how that would have happened.
Steven Ford
Professional Imaging Services, Inc.
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Reader Mail
Tue. 14 Feb.12,
20:40
[Reply (1 of 2) to:
'Shoulder orientation'
started by: 'Reader Mail'
on Thu. 2 Feb.12]
Category:
General
|
| Shoulder orientation |
Due to the steep angle, the orientation changes from coronal to sagittal.
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