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| Result: Searchterm 'ffe'
found in 134 messages |
| Result Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 [19] 20 21 22 23 24 25 26 27 |
More Results:  Database (446) News Service (436) Resources (66) |
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Sam Shelly
Sun. 2 Nov.08,
23:02
[Reply (2 of 3) to:
'Regarding recovery and decay [basic phycisc]'
started by: 'harry sanders'
on Sat. 7 Jun.08]
 Category:
Basics and Physics
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| Regarding recovery and decay [basic phycisc] |
Right on.
Recovery and delay are two separate physical processes like the last guy said. It had me stumped for a while when I was studying as well. But read carefully and think hard about it...
T1 recovery is the return of net magnetization into alignment with b0.
T2 decay is a totally different process and is, as the previous person said, simply loss of net magnetization in the transverse plain due to dephasing. The more electrons that are precessing in phase in the transverse plane, the stronger the NMV is in that plane. And, hence forth, when the RF pulse terminates, the influence of b0 gradually dephases the electrons in the transverse plane. As they dephase, the transverse NMV decreases accordingly, until the next pulse hits, rephasing the electrons and starting the process all over.
Hope that helps. MRI physics is hairy and boring at times. Load up on expressos to stay awake and stick with it, because studying MRI physics can be like taking a bottle of sleeping pills.
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Maricella Sauceda
Thu. 16 Oct.08,
22:33
[Start of:
'Translation of MRI Result - Help'
0 Reply]
Category:
Applications and Examinations
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| Translation of MRI Result - Help |
Okay... So below is what the MRI breakdown tells me, can someone tell me if I should definitely be worried... I think it says I have brain lessions associated to sinus problems, but then they said it might be a sign of MS? HELP... Any additional clarity will be greatly appreciated...
Technique: Sequences spin - echo-enhanced in T1, T2 protons and density, flair at the axial, sagittal and coronal, 5 mm thick.
Report:
Small punctate signals focal hypo-intense in T1 and hypertensive in the other sequences and without apparent mass effect in the lobar white matter and subcortical frontal, bilateral parietal subcortical and peri-ventricular the atriums of both lateral ventricles.
Others are not displayed disturbances of encephalic parenchyma or blood collections or intra extraxiales. The medulla oblongata, pons and the cerebral peduncles with normal morphology and signal. Tanks of the base, the subarachnoid space and the cortical ventricular system above and infratentorial not dilated, without compression or movement.
Thickening of the lining which is the frontal sinuses, ceidillas etmoidales and maxillary sinuses, in the latter left with the presence of liquid level.
Comments
Many small pictures that compromise the lobar white matter and subcortical frontoparietal and peri-ventricular atrial bilateral and that although might be nonspecific, it is not possible to rule out entirely demyelinating etiology, so it must be correlated with the clinic's patient, findings of physical examination and clinical-. A new study of control in timely fashion or according to clinical course can be useful.
Pan-chronic sinusitis with signs of acute in the left maxillary sinus.
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German Villegas
Tue. 14 Oct.08,
22:11
[Reply (3 of 4) to:
'Contrast MRA COW.'
started by: 'Marilia White'
on Thu. 3 Mar.05]
Category:
Contrast Agents
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| Contrast MRA COW. |
Just came from an MRI convention by Bill Faulkner according to him CE MRA COW is a very Diagnostic exam, no undesireble veins! I thought the same but it appears this exam has proven to be valuable in the diagnosis of oclusions, stenosis and aneurysms. I do not have a protocol, but am working to build one. I will post suggestions once I got something that works. Bill did mention it must be a dynamic scan quick enough to show arterial flow and then venous, so no more than 10 seconds per scan. Very few centers and hospitals offer this protocol but its in the works.
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John Jackson
Fri. 12 Sep.08,
08:48
[Reply (1 of 3) to:
'Regarding recovery and decay [basic phycisc]'
started by: 'harry sanders'
on Sat. 7 Jun.08]
Category:
Basics and Physics
|
| Regarding recovery and decay [basic phycisc] |
Hi,
I'm not so sure but I think because different physical process are being involved. Longitudal relaxation has got something to do with energy exchange to the environment. Transverse relation occurs because of spin dephasing (magnetic inhomogenity.)
John
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John Jackson
Fri. 12 Sep.08,
08:40
[Reply (1 of 2) to:
'flow arifact'
started by: 'Neeta Vyas'
on Tue. 9 Sep.08]
Category:
Artifacts
|
| flow arifact |
I wonder if it has anything to do with the placement (location) of the wrist within the scanner. Assuming that your using the scanners coil as a reciever- Are you scanning close to the edge of the scanner? The sat band also has to be within the FOV/limits of the scanner.
I suggest trying different locations in the scanner (or using a smaller FOV). It would be strange if you had artefacts in some writs and not in others.
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