The methods CreateVTCinVMRSpace(), CreateVTCinACPCSpace() and CreateVTCinTALSpace() do have three extra parameters compared to the CreateVTC() method. These are target resolution, interpolation method and intensity threshold.
Target resolution
The resolution is given in a single cubic size parameter, that can be 1, 2 or 3 (mm3).
Interpolation method
1.9.10 situation: To request sinc interpolation for the "CreateVTC*" set of commands, use value "2" for the "InterpolationMethod" parameter ("1" for trilinear, "0" for nearest neighbor interpolation).
Pre-1.9.10 situation: Currently only the trilinear interpolation method is available. Enter value 1 to select this method.
Bounding box
Although the bounding box for VTCs can be set in different ways for different coordinate spaces (VMR and AC-PC vs. Talairach), please do always set the parameter ExtendedTALSpaceForVTCCreationspace before creating the VTC to ensure that you get the bounding box in the size you want.
In VMR and AC-PC space: intensity threshold
In BrainVoyager QX this is default '100'. All image values higher than 100 will be taken into account for the determination of relevant voxels in the functional image. This value is relevant when the transformation of the functional data is not up to Talairach space.
In case a lower threshold for finding brain voxels is chosen, the algorithm is likely to find more voxels so that the size of the bounding box will expand (axes are BrainVoyager internal coordinate system):
Threshold 100 (default):
x: 20 x 173
y: 23 x 218
z: 54 x 159
Threshold 80:
x: 19 x 172
y: 21 x 234
z: 54 x 159
Threshold 40:
x: 15 x 177
y: 12 x 234
z: 54 x 162
In Talairach space: extended Talairach space
To use the extended Talairach space option including the cerebellum, set the VMR property ExtendedTALSpaceForVTCCreationspace to true before invoking the method CreateVTCinTALSpace(). So this option does not need to be passed as a parameter to the function. The parameter is default set to false and will thus by default create a VTC in the standard grid space.
/* Script that asks for relevant files and creates VTCs with different bounding boxes.
To see the size of the bounding box, load the VTC file and go in BrainVoyager to File >
VTC Properties.*/
function Use_different_VTC_parameters() {
var vmr = BrainVoyagerQX.OpenDocument(FileDialog.getOpenFileName("*.vmr"));
var fmr = FileDialog.getOpenFileName("*.fmr");
var ia = FileDialog.getOpenFileName("*_IA.trf");
var fa = FileDialog.getOpenFileName("*_FA.trf");
var acpc = FileDialog.getOpenFileName("*_ACPC.trf");
var tal = FileDialog.getOpenFileName("*.tal");
vmr.CreateVTCInVMRSpace(fmr, ia, fa, "tst_40.vtc", 3, 1, 40);
BrainVoyagerQX.PrintToLog("Test with threshold 40");
vmr.CreateVTCInACPCSpace(fmr, ia, fa, acpc, "tst_80.vtc", 3, 1, 80);
BrainVoyagerQX.PrintToLog("Test with threshold 80");
vmr.ExtendedTALSpaceForVTCCreationspace = false;
vmr.CreateVTCInTALSpace(fmr, ia, fa, acpc, tal, "tst_100.vtc", 3, 1, 100);
BrainVoyagerQX.PrintToLog("Test with threshold 100 (default)");
vmr.ExtendedTALSpaceForVTCCreationspace = true;
vmr.CreateVTCInTALSpace(fmr, ia, fa, acpc, tal, "tst_100_extended.vtc", 3, 1, 100);
BrainVoyagerQX.PrintToLog("Test with threshold 100 (default) and extended space");
}
See also the sample Script to quickly create 3 VTCs in TAL space