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| Result: Searchterm 'Echo'
found in 43 messages |
| Result Pages: 1 2 3 [4] 5 6 7 8 9 |
More Results:  Database (305) News Service (7) Resources (10) |
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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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|  View the whole thread | | |
Mel Chang
Thu. 21 Oct.10,
19:26
[Reply (1 of 2) to:
'cervicla axial image t2 and t2*'
started by: 'kim jk'
on Thu. 23 Sep.10]
Category:
Applications and Examinations
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| cervicla axial image t2 and t2* |
T2* is fine to scan the intervertebral discs. T2 is the better choice to show small spinal cord lesions like MS plaques. The echo time of a T2* sequence may be not long enough to give a good differentiation between the pathology and surrounding tissue.rnDifferent 'Multi Echo Data Image Combination' (MEDIC) techniques have been developed to enhance contrast and pathology detection, if available on the scanner this type of sequence is maybe also a good choice, but due to longer scan times and artifact problems it is best for axial slices.rn
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| | View the whole thread | | |
Leak Sea
Sat. 16 Oct.10,
14:44
[Start of:
'How to fill the K-space?'
1 Reply]
Category:
Basics and Physics
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| How to fill the K-space? |
Hi,
i've been learning MRI for some weeks, and i really want to know that when we use the spin-echo sequences, how can we fill the data into K-space line by line?
i learned the steps of spatial encoding, but i need the algorithm, or the equations, or the quantitative way to fill the K-space.
thanks a lot!
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Jacob Newton
Thu. 7 Oct.10,
19:22
[Reply (1 of 2) to:
'How does TE affect DWI acquisition?'
started by: 'danilo Scelfo'
on Wed. 29 Sep.10]
Category:
Sequences and Imaging Parameters
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| How does TE affect DWI acquisition? |
I never tried to shorten only the echo time while keeping all other parameters the same, but I would expect a change in SNR and artifact appearance. I would use parallel imaging methods to get a shortest possible echo time. Parallel imaging provides DWI with shorter echo trains associated with further reduction of the echo and repetition times, which reduces susceptibility effects and also image blurring. Additionally, the shorter echo time may lead to changes in ADC measurement.
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| | View the whole thread | | |
George LoGuirato
Wed. 7 Apr.10,
13:28
[Reply (1 of 2) to:
'Proton Density Imaging'
started by: 'Jacquelyn Chiffons'
on Thu. 18 Mar.10]
Category:
Sequences and Imaging Parameters
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| Proton Density Imaging |
A Proton Density - like a T1 or T2 - is not considered anything; it is what you make it. Most all PD's are run as fast (turbo) spin echo, but many sites run a true spin echo PD on knees to evaluate the meniscus. (It's a long sequence.)
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