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| Result: Searchterm 'HIS'
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More Results:  Database (430) News Service (375) Resources (57) |
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George LoGuirato
Wed. 3 Mar.10,
15:38
[Reply (1 of 2) to:
'Dynamic Imaging'
started by: 'Ron Harris'
on Tue. 2 Mar.10]
 Category:
Applications and Examinations
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| Dynamic Imaging |
Don't have a solid definition, but will give an example. Pituitary study: you can run a dynamic study by using a power injector set for a slow infusion rate of let's say 0.75ml/sec. The scanner is set to run a scan sequence through the PIT (25-35 seconds) and then repeat that sequence usually six times. The dynamic "uptake" and "falloff" of contrast in the PIT is evident.
Hope this helps.
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|  View the whole thread | | |
Oliver Lyttelton
Mon. 1 Mar.10,
13:39
[Reply (8 of 12) to:
'90 excitation pulse vs 180 inversion pulse'
started by: 'Bjorn Redfors'
on Sat. 27 Jun.09]
Category:
Basics and Physics
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| 90 excitation pulse vs 180 inversion pulse |
Okay, so this thread is answering close to a question I had, which is how to conceptually understand what happens with alpha>90 degrees excitation pulses.
I can imagine spinning tops, precessing at the Larmor frequency, I can imagine that as you apply the excitation pulse which is always in the transverse plane to the main magnet, you start to pull the tops further away from the B0 axis and bring them into coherence so like lots of little lighthouses they are all bright/dark in phase with each other. I can imagine a 90 degree pulse bring the spins completely into the transverse plane. I can imagine them relaxing, dephasing quickly and then slowly reducing their angle of precession back up towards initial state close to direction B0.
But what I can't understand in my (rather newtonian) model, is what happens as you continue to excite beyond the 90 degree transverse plane. I sort of get that somehow the spins continue to rotate in some (weird) dimension, and that they have to come back through that (weird) dimension first before returning from 90 degrees back to the relaxed state. But what happens in "weird" dimension is beyond my conceptual model. Can someone extend my model for me, preferrably without signal equations?
tar muchly,
Oliver
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| | View the whole thread | | |
Ricardo Flores
Sat. 23 Jan.10,
08:56
[Reply (11 of 26) to:
'MRI Technologists Jobs in Saudi Arabia'
started by: 'Mosta Mosta'
on Tue. 3 Mar.09]
Category:
Jobs
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| MRI Technologists Jobs in Saudi Arabia |
Hello my name is Ricardo Flores. I have 13 yrs radiology experience and 4+yrs MRI. I know GE and Siemens platforms. Can you tell me what the pay is for a job overseas like this.
xrayman1@optonline.net
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| | View the whole thread | | |
Gee Del
Thu. 7 Jan.10,
04:37
[Start of:
'Contrast regulation/Law'
1 Reply]
Category:
Contrast Agents
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| Contrast regulation/Law |
Does anybody know if there is a regulation regarding the doctors need to be present or within the premises during contrast inject for safety purposes? If somebody can provide an article or link regarding regulations or laws during this process.
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Iosif Sogolov
Sun. 3 Jan.10,
20:49
[Reply (7 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 |
prior 90: spins precess around B0 uncoherently, there for the sum of their projections on TRANSVERSE plane is ZERO, they are "unfocused" in this plane. 90 and right after: all above mentioned spins are forced to rotate around B1, it should be stressed - in only one for ALL of them chosen direction of rotation (depends of B1 direction) to the TRANSVERSE plane, they all will come compact to this plane and now they do give here NET MAGNETIZATION, become "focused".
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