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MRI Forum
'Magnet'
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Result: Searchterm 'Magnet' found in 87 messages
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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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Steven Ford

Thu. 3 Mar.11,
20:28

[Reply (1 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
I assume that you mean a t2 fat suppressed sequence. Differing gradient strengths have only an indirect effect on these images. The fat saturation sequences require additional pulses which take time to execute; stronger gradient systems can execute these pulses faster.

If you see different results, it can be caused by a number of factors; if you can describe the differences, that would be helpful. Generally speaking, the quality of the magnet homogeneity makes a big difference. If the small FOV scans (wrist) look different from magnet to magnet, that's probably not the cause.

You should ask your MRI applications specialist about this, and pay attention to the TE and bandwidth. Are the FOV and number of steps the same?
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Steven Ford

Tue. 15 Feb.11,
17:15

[Reply (2 of 3) to:
'acceptable levels of cryoges'
started by: 'vasi red'
on Thu. 10 Feb.11]


 
  Category: 
Site Planning and Specifications

 
acceptable levels of cryoges
The 'safe' level of liquid helium depends on the specific magnet that you have. 40% is accurate for some magnets.
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Don LaVille

Tue. 21 Dec.10,
20:57

[Reply (1 of 3) to:
'Muscle shading in 3T Images'
started by: 'Travis Conley'
on Thu. 21 Oct.10]


 
  Category: 
Applications and Examinations

 
Muscle shading in 3T Images
This artifact is known as the dielectric effect. It is a phenomena to all magnets. At 1.5T the dielectric effect is at 60cm so when we scan at a FOV of 40 or less we don't see it. At 3t the dielectric effect is reduced to 30cm so we now see it when using a FOV of 30 or more. There is no way to get rid of it that I know of and you will see an increase with patients with more magnetic suseptibility (ie. patients with ascities, and pregnant patient). You could try using Surface Coil Intensity Correction (SCIC) and it will help to even out the extreme dark and light in your image. Some vendors will suggest using a Fat Sat pad to help reduce this artifact. I have tried it with little success.
Looking at your image, it looks like you were scanning on a GE 3T HDX. I hope that the vendors will have a fix for this artifact soon. For right now though we are just dealing with it. I hope this helps.
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Muhammad Arshad

Sat. 28 Aug.10,
12:16

[Reply (14 of 26) to:
'MRI Technologists Jobs in Saudi Arabia'
started by: 'Mosta Mosta'
on Tue. 3 Mar.09]


 
  Category: 
Jobs

 
MRI Technologists Jobs in Saudi Arabia
I am MRI and CT Technologist in King Abdullah Medical Makkah. I am working on Siemens MRI Magnetom Espree and Somatom 64 slice ct.
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