| T O P I C R E V I E W |
| jvbinzak |
Posted - Jun 21 2011 : 5:48:57 PM
I'm new to data processing so for give me if this comes off poorly. In the instances where my subjects QA shows a substancial RF spike or head displacement, I have been instructed to "Calculate a Difference Image" using MATLAB. My understanding is that this will allow me to remove the spikes and movement from my data before the first level of analysis.
Does anyone have experience dealing with managing large RF spikes and moments of head movement in their data? If so, what all is possible fix the data, and how do I go about it?
Specifically, can someone outline a step by step procedure to calculate a difference image using MATLAB? If so please make it as overt/fool proof as possible. |
| 1 L A T E S T R E P L I E S (Newest First) |
| dvsmith |
Posted - Jun 22 2011 : 10:39:53 AM
Calculating the difference image (timepoint-to-timepoint difference) would mainly just allow you to better visualize the spikes and artifacts. If you want to do that, it's pretty easy to do:
funcfile = readmr(funcfile);
funcfile.data = diff(funcfile.data, 1, 4);
If you want to quantify and model spikes, you should take a look at an FSL tool called fsl_motion_outliers. It's also very easy to use.
Usage: fsl_motion_outliers <unfiltered 4D image> <number of dummy scans> <output confound file>
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