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| Result: Searchterm 'Signa'
found in 78 messages |
| Result Pages: 1 2 3 4 5 6 7 8 [9] 10 11 12 13 14 15 16 |
More Results:  Database (382) News Service (60) Resources (16) |
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kim jk
Thu. 23 Sep.10,
06:37
[Start of:
'cervicla axial image t2 and t2*'
1 Reply]
 Category:
Applications and Examinations
|
| cervicla axial image t2 and t2* |
hello
every one
may i have question ~
why used for cervical axial t2 star instead of t2 in signa 1.5t ?
and what differnt t2 star between t2 of pathology ..?
umm,, my english is pool,, sorry about that,,
bye..
wating for kindly answer~
jk
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Azza Ahmed
Thu. 8 Jul.10,
10:42
[Start of:
'exceeding slew rates'
0 Reply]
Category:
Sequences and Imaging Parameters
|
| exceeding slew rates |
Can someone please let me know what happens to the MRI signal intensity if any of the gradient's slew rate was exceeded?
Azza AhmedrnPhD student
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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
|
| 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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George LoGuirato
Thu. 18 Feb.10,
16:26
[Reply (1 of 2) to:
'bandwidth'
started by: 'Stephen Roberts'
on Mon. 15 Feb.10]
Category:
Devices, Scanner, Machines
|
| bandwidth |
Quite possible. Manufactures like their own designations for bandwidth for ??? reasons. GE uses true bandwidth in KHz. Siemens uses Hz/PIXEL. Not sure what Toshiba uses. Contact Toshiba applications for designator and conversion factor.
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Stephen Roberts
Mon. 15 Feb.10,
16:40
[Start of:
'bandwidth'
1 Reply]
Category:
Devices, Scanner, Machines
|
| bandwidth |
Are there differences in the bandwidth numbers as to how it is designated from let's say GE and Toshiba?
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