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+ | ====== voi.AddSphericalVOI ====== | ||
+ | ===== Motivation ===== | ||
+ | In many cases, researchers already have a priori selected areas/regions which are candidates for testing specific hypothesis, which gives greater detection power (at least when, on the other hand, researchers apply customary multiple-comparison correction algorithm if they decide to perform whole-brain searches for effects that match their hypothesis!). | ||
+ | |||
+ | Often these regions of a priori interest are given as an estimate of a central coordinate around which a spherical shape is defined with a given radius. This method allows to create ROIs that conform with that notion. | ||
+ | |||
+ | ===== Method reference ('voi.Help('AddSphericalVOI')') ===== | ||
+ | <file> VOI::AddSphericalVOI - add a spherically shaped VOI to the object | ||
+ | |||
+ | FORMAT: [voi = ] voi.AddSphericalVOI(c, r); | ||
+ | |||
+ | Input fields: | ||
+ | |||
+ | c 1x3 coordinate (center) | ||
+ | r 1x1 radius (must be > 0 and < 128) | ||
+ | |||
+ | Output fields: | ||
+ | |||
+ | voi VOI with added VOI (integer coordinates only!)</file> | ||
+ | |||
+ | ===== Example ===== | ||
+ | To add one specific ROI to a new VOI object around, say, coordinate (-24, -4, -22) (the Talairach Atlas resolves to the left Amygdala on that coordinate) with a radius of 6mm, you can use the following code: | ||
+ | |||
+ | <code matlab voi_addsphericalvoi_example1.m>% create VOI object | ||
+ | voi = xff('new:voi'); | ||
+ | |||
+ | % add ROI | ||
+ | voi.AddSphericalVOI([-24, -4, -22], 6);</code> | ||
+ | |||
+ | To add multiple VOIs (e.g. from a table of coordinates), you could use this: | ||
+ | |||
+ | <code matlab voi_addsphericalvoi_example2.m>% create VOI object | ||
+ | voi = xff('new:voi'); | ||
+ | |||
+ | % coordinates are in a Cx3 table, ctab, and the radius is fixed at 8mm | ||
+ | % alternatively, the radius could be in column 4 in a Cx4 table | ||
+ | |||
+ | % iterate over coordinates in table | ||
+ | for cc = 1:size(ctab, 1) | ||
+ | |||
+ | % add coordinate | ||
+ | voi.AddSphericalVOI(ctab(cc, 1:3), 8); | ||
+ | % or alternatively: | ||
+ | % voi.AddSphericalVOI(ctab(cc, 1:3), ctab(cc, 4)); | ||
+ | | ||
+ | end</code> |