Hi all,

I would like to recompute the movement parameters taking into account only the first 120 volumes. How is the motion.cvs excel file calculated. Do the colums F to K (Max X (mm), Max Y (mm), Max z (mm), Max Roll (degree), Max Pitch (degree), Max Yaw (degree)) simply represent the max value for each of the columns in the indivual rp.1D files? I've tried to calculate the max value with excel on the individual rp.1D data and I didn't get the same results. I'm sure I might be doing something wrong but I don't know what.
Also, once I have to right values, how do I recalculate Max Motion (mm) and the Max Rotation (degrees)?. Is it just a geometric mean of x,y,z values of each timepoint in the case of the Max motion and a geometric mean of the pitch, roll and yaw values of each time point in the case of Max Rotation?

Thanks a lot for your help

Susanna

Hello Susanna,

The perl script that I use to calculate the motion parameter summary statistics can be downloaded here: http://www.nitrc.org/frs/downloadlink.ph... or from the Athena wiki page.

I did use the max _absolute_ value for each of the columns, maybe that is the difference between your script and mine?  

To calculate max motion, I first compute the geometric mean of the translation at each TR and then take the maximum of these statistics.  I did the same for rotation.

This might not actually be the best way to summarize motion for quality control.  Another method measures the amount of motion between each pair of TRs and takes the maximum of this value.  The justification is that even a very large amount of motion can be corrected if it is very slow motion, i.e. no quick large transitions.

Cheers,
Cameron

Hi,

I downloaded the perl script to calculate motion. I am agree with your definition which is max_absolute _value for each of the columns as Max_x. However, I am sorry to be confused with the code said "if( abs($x) > $max_x ) } {$max_x = $x}". When max_x becomes negative, any abs($x)> max_x  is correct and further max_x would be covered. Actually, I have calculated max_absolute _value for each of the columns on the individual rp.1D data and the results are different from the published motion.cvs excel file. 

Thanks so much for your reply