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| Result: Searchterm 'tr'
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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
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| 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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| | View the whole thread | | |
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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| | View the whole thread | | |
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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| | View the whole thread | | |
Robert Patten
Thu. 3 Mar.11,
22:08
[Start of:
'Building 3d Volumes from MRI DICOM'
4 Replies]
Category:
General
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| Building 3d Volumes from MRI DICOM |
I have a number of MRI and CTs since a bad accident. I am a Mechanical Engineer with an electrical, power and computer background.
I was able to render the CT to 3D using Onis (not sure if you've seen this program), but have been unable to manage it with any of the MRIs.
The MRIs were taken on a Phillips Intera 1.5T
I can render a volume but only (1) of the (3) 2D images are clear before it is rendered and the resulting 3D image is just noise. I've tried various software packages and spent a lot of time with the software. Perhaps I don't have the required image files.
Maybe someone knows the answer.
Thanks,
Bob
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