• System Requirements
• Data Requirements

• UNIX or Linux operating system.
• IDL version 5.2 or higher.

1) there exist one file for each data volume,
2) the file format is either Analyze or VAPET,
3) there exists a volume list file

A volume list file (VLF) is an ASCII file holding useful information on the volumes in a data set.

NPAIRS does not perform any data pre-processing. As such, it is highly recommended that your data also adhere to the following:

• All volumes within a scan session are aligned to correct for motion (intra-subject alignment). A popular choice to perform this operation is the AIR package by Roger Woods.
• All volumes within a data set are aligned to a common coordinate system, e.g, Talairach. This is often called inter-subject alignment. This is necessary only when the data set consists of multiple subjects. Again, a popular choice to perform this operation is the AIR package by Roger Woods.
• The data is spatially smoothed to a desired resolution, usually specified as a FWHM in each of the 3 spatial dimensions.
• A mask volume exists for each volume and is saved as either an Analyze or VAPET file. A mask volume holds 0's and 1's, with 0 indicating a non-brain voxel and 1 indicating a brain voxel. If the volumes within a scan session have been intra-subject aligned, then one mask volume can be used for all the volumes. Mask volumes are used for 2 purposes: 1) to guarantee only brain voxels are analyzed, and 2) to reduce the size of the data matrix by excluding the numerous non-brain voxels.