[Freesurfer] Content of PET gtm.stats.dat file

Hello FreeSurfer Developers,

I have run mri_gtmpvc command to perform PET PVC (partial volume correction) where input data has 4 frames (dynamic). The output volume as gtm.nii.gz has 4 frames as well which means that PVC was performed for each frame separately. However, gtm.stats.dat file has one value for each ROI. At first I thought it was the average of all frames but after manually comparing some ROIs it seems that the values in the file are taken only from the first frame of dynamic data. Is it the case or those values have another interpretation? Maybe it is the highest value across all frames? In addition, is there an easy way to get the same file where the values would be the average across all frames?