Physiology: Difference between revisions
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Note: For those of you who use the Philips MR Physiology recording system to measure and analyze VCG and respiratory signals, it is good to know that MR scanners with wireless VCG devices have a different sampling frequency than wired systems. Philips reports the sampling frequency of current wireless systems to be 496Hz. Based on gradient signals in the log files a rate of 496.03Hz has been reported (roughly a 0.2s difference on an hour measurement). The frequency of wired systems (7T!) is 500Hz. In most use cases this difference is negligible within fMRI trials, but the time difference can vary significantly over longer periods of time. | Note: For those of you who use the Philips MR Physiology recording system to measure and analyze VCG and respiratory signals, it is good to know that MR scanners with wireless VCG devices have a different sampling frequency than wired systems. Philips reports the sampling frequency of current wireless systems to be 496Hz. Based on gradient signals in the log files a rate of 496.03Hz has been reported (roughly a 0.2s difference on an hour measurement). The frequency of wired systems (7T!) is 500Hz. In most use cases this difference is negligible within fMRI trials, but the time difference can vary significantly over longer periods of time. | ||
For a detailed overview of physiology log files on Philips scanners, see [[Media:Philips_Physiology_Logging.pptx| this PowerPoint]] | |||
The following scripts can be helpful when dealing with physlog files: | The following scripts can be helpful when dealing with physlog files: | ||
* Matlab: https://nl.mathworks.com/matlabcentral/fileexchange/42100-readphilipsscanphyslog-filename-channels-skipprep | * Matlab: https://nl.mathworks.com/matlabcentral/fileexchange/42100-readphilipsscanphyslog-filename-channels-skipprep | ||
* Python: https://community.mr-paradise.com/t/physlog-file-reader-in-python/3192 | * Python: https://community.mr-paradise.com/t/physlog-file-reader-in-python/3192 | ||
Latest revision as of 16:38, 4 November 2021
1. Take 2 batteries from the battery charger in the control room and put them in both the PPU (3) and VCG (4) unit, even if you only use PPU. You may leave the VCG unit in the closet if you don’t use it.
2. Place the respiratory sensor (1) horizontally +/- 5 cm above the navel of your subject and secure it with the Velcro band.
3. Put the finger clip (2) on the left ring finger. Put the side with the light on the opposite side of the finger nail.
4. In the control room, press the right mouse button on the bottom left side of the screen when you are in the application software and choose PPU + Resp to show the measurements on the bottom left.
5. The measurements are also shown on the little screen on the scanner.
6. To remove the battery from the unit, first push the battery handles on the sides before you pull out the battery. The batteries last +/- 1 hour, so preferably change them for every participant and always put the used ones in the charger immediately. Put all batteries back in the charger when you are finished scanning.
7. Your physiology data will be automatically exported with Flywheel. If you want to manually export your physiology data you can do this from G:/log/physlog or use the gtPacknGo software.
Note: For those of you who use the Philips MR Physiology recording system to measure and analyze VCG and respiratory signals, it is good to know that MR scanners with wireless VCG devices have a different sampling frequency than wired systems. Philips reports the sampling frequency of current wireless systems to be 496Hz. Based on gradient signals in the log files a rate of 496.03Hz has been reported (roughly a 0.2s difference on an hour measurement). The frequency of wired systems (7T!) is 500Hz. In most use cases this difference is negligible within fMRI trials, but the time difference can vary significantly over longer periods of time.
For a detailed overview of physiology log files on Philips scanners, see this PowerPoint
The following scripts can be helpful when dealing with physlog files: