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| Result: Searchterm 'Gradient'
found in 38 messages |
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Elise Gough
Mon. 7 Mar.11,
16:54
[Reply (7 of 8) to:
'6-1.5T MAGNETS, DIFFERING GRADIENTS'
started by: 'Elise Gough'
on Wed. 23 Feb.11]
 Category:
Applications and Examinations
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| 6-1.5T MAGNETS, DIFFERING GRADIENTS |
Thank you for your logical advice. Just spoke with GE apps. "No amount of messing with MR parameters can compensate for weak gradients. Increased gradient strength=decreased echo spacing=less blurring". Coincidently, my DO just emailed me asking what the gradient strength is on the magnet the RADs are complaining about.Just MAYBE they'll upgrade it. I need to visit our sites.The only way I have to check other sites' parameters is importing exams from PACS to my modality console. Tedious, but telling. Again, thankyou for all the help.
Elise Gough RT(R)(CT)(MR)
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|  View the whole thread | | |
Elise Gough
Mon. 7 Mar.11,
15:56
[Reply (5 of 8) to:
'6-1.5T MAGNETS, DIFFERING GRADIENTS'
started by: 'Elise Gough'
on Wed. 23 Feb.11]
Category:
Applications and Examinations
|
| 6-1.5T MAGNETS, DIFFERING GRADIENTS |
Thanks so much for the input. NOBODY in my group seems to have a handle on why images vary in quality from 8 different magnets. I'm being pressed to take position of imaging specialist and thru my own research we have gradient strengths from 50 slew rate up to 120. Radiologists complain neuro stinks on the 50 slew rate 1.5T magnet and it is the most pounded on magnet in our group doing hospital inpatients. So many variables including tech expertise.
Elise Gough RT(R)(CT)(MR)
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| | View the whole thread | | |
Steven Ford
Mon. 7 Mar.11,
15:24
[Reply (4 of 8) to:
'6-1.5T MAGNETS, DIFFERING GRADIENTS'
started by: 'Elise Gough'
on Wed. 23 Feb.11]
Category:
Applications and Examinations
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| 6-1.5T MAGNETS, DIFFERING GRADIENTS |
If some of the system are signal starved, it's most likely not due to gradient field strength and speed, but it can be related to that. Like everything else in MRI, it's complex and interdependent.
You're best advised to talk with the apps specialist from the systems that are under-performing, and learn from them what the bandwidth is, and also check the shim. Is the fat suppression OK, but the signal weak, or is the suppression bad also? Do you get a graphic output of the linear (gradient)shim corrrection on the various systems?
It is well worth the money that they might charge, if it comes to that, in order to optimize the use of the systems and for your own education. If the apps person does not know why the other machine works so well, there should be someone higher up in the organization who can shed some light on your question.
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Renate Semrau
Mon. 7 Mar.11,
15:11
[Reply (3 of 8) to:
'6-1.5T MAGNETS, DIFFERING GRADIENTS'
started by: 'Elise Gough'
on Wed. 23 Feb.11]
Category:
Applications and Examinations
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| 6-1.5T MAGNETS, DIFFERING GRADIENTS |
Slew rate, rise time and/or duty cycle are specific parameters to describe the performance of the gradient amplifier. Amplifiers with higher performance allow a faster slew rate (shorter rise time). Stronger gradients allow to reduce echo time, increase the bandwidth and/or use a smaller FOV by influencing the SNR. To use same parameters on magnets with different gradient performance may not be recommended, or you have to adjust all parameters to the level of your magnet with the poorest performance.
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Elise Gough
Fri. 4 Mar.11,
13:56
[Reply (2 of 8) to:
'6-1.5T MAGNETS, DIFFERING GRADIENTS'
started by: 'Elise Gough'
on Wed. 23 Feb.11]
Category:
Applications and Examinations
|
| 6-1.5T MAGNETS, DIFFERING GRADIENTS |
Thank you for your response. Our group is strict about FOV, thickness/gap parameters being the same across all magnets. One magnet has slew rate of 77, FRFSE T2, TE 85,TR 3500 Classic Fat supressed images which are pristine, vs magnets of 120 slew rate same parameters look signal starved. So gradient strength makes a speed difference, not an image quality difference?
Elise Gough RT(R)(CT)(MR)
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