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allen.song
BIAC Faculty
USA
35 Posts |
 Posted - Dec 01 2005 : 4:27:07 PM
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GE is wrapping up their test around 5:00 pm today, and I am waiting to get on the scanner for my final tests. Among these tests, the stability of the newly modified spiral-in pulse sequence will be a primary focus, as I have made modifications in my source code to reverse the rotation direction. If the stability holds well, Jimmy will be updating the daemons running on the various BIAC workstations to incorporate my changes in the reconstruction software to accommodate the new spiral rotation. Since we really don’t have much time to test every aspect of the reconstruction pipeline before tomorrow morning, there may be reconstruction problems for some early scans. Please keep us informed if you see anything peculiar in your images. But since your p-files will be saved, we can always re-run the reconstruction to get the right images, should there be a real problem.
Of course, all other pulse sequences should work as is.
I will make a new announcement to either confirm the uptime or request more downtime, hopefully not the latter.
Sincerely,
Allen
******************** Relevant Previous Post *********************
Projected 3T Uptime: Noon, this Thursday
We are making progresses on several fronts:
1) Regarding spiral-in scans: it turns out that the rotation direction can have a large effect on the stability. By rotating the spiral direction, we (Scott Hinks and I) were able to get some clean images. Even though the reasons for this phenomenon are not completely known at this point, we may have an interim fix. I am currently modifying my pulse sequence to change the rotation pattern and will run many tests today and tomorrow to confirm its effectiveness.
2) Regrading strips in anatomical images and "hot flashes" in functional scans: GE has completely cleaned up the spikes in the raw data that are contributing to the strips in the images. They are running more tests to ensure a long-term robustness.
3) Regarding occational dark anatomical images: GE is assessing the dark image problem seen in some of the anatomical scans, and hopefully with the replacement of the body RF coil (which has been done), the images will be clean from now on.
Since all the software and hardware changes and the subsequent fidelity tests will take some time for GE scientists, engineers and myself, the projected uptime will be noon this Thursday. If the uptime turns out to be earlier than that, I will make a new announcement.
Again, thanks for your continued support and patience. These problems, although not frequent, do occur in leading academic centers where we constantly push the technology to the limit of the instruments. Some of the problems we experienced, such as the recent spiral-in image instabilities, were new even to leading manufacturers such as GE. I hope that all of you would understand this, and that we will come out from the better end of it.
Sincerely,
Allen
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New Projected Uptime for 3T: Friday Morning
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