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| Result: Searchterm 'DWI'
found in 27 messages |
| Result Pages: 1 2 [3] 4 5 6 |
More Results:  Database (41) News Service (47) Resources (15) |
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Brent Johnson
Wed. 21 Aug.13,
19:38
[Start of:
'Hitachi Airis II question'
0 Reply]
 Category:
Sequences and Imaging Parameters
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| Hitachi Airis II question |
I have a question for a Hitachi Airis II .3T non-upgraded gradients
On T2 FSE sequences especially on thumb sagittal slices. Image quality very poor, grainy. What is ideal bandwidth and TE settings for improving image quality? Also is positioning and angle of slice a factor in image quality. The closer the anatomy is to edge of coil, does that effect image quality.
Thanks Brent
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Reader Mail
Sat. 7 Jan.12,
11:29
[Start of:
'Diffusion Weighted Images'
0 Reply]
Category:
Applications and Examinations
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| Diffusion Weighted Images |
What are the best sequences for evaluating of the female pelvis. Regarding that I am doing a research on the role of DWI in characterization of female pelvic masses. Our machine is a Hitachi Airis Avento. I did not find the b value, however a diffusion button is there. rn
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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
|
| 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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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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