PowerPoint Presentation

-16-

ĄNote: A ROI is defined by the values stored in voxels of the ÔmaskŐ dataset

HContiguity of voxels has no meaning to the ROI software described below

HTwo voxels are in the same ROI if they have the same value in the mask dataset (i.e., it doesnŐt matter where they are located in the volume)

Ą3dmaskave

HProgram to compute the average of voxels from a functional dataset, with voxels selected from a mask dataset (interactive version: ROI Average plugin)

HExample:

3dmaskave -mask ROI_fred+tlrc -mrange 1 4

`func_fred+tlrc[2,5,7]`

Will print out (in the shell) one line of data for each of the 3 selected sub-bricks from the input dataset func_fred+tlrc:

44.287 [137 voxels] Âsub-brick #2 values averaged across all 4 ROIs

27.021 [137 voxels]

Âsub-brick #5 values averaged across all 4 ROIs

-33.22 [137 voxels]

Âsub-brick #7 values averaged across all 4 ROIs

ĺThe output above represents the average of all the voxels collapsed across ROIŐs 1, 2, 3, 4, (specified by -mrange 1 4) in our mask dataset ROI_fred+tlrc for sub-bricks #2, #5, and #7 from dataset func_fred+tlrc