fmri_dicemirror

Description

FMRI_DICEMIRROR Mirrored Dice coefficient of a binary brain mask. Measures the bilateral symmetry of a brain mask by computing the Dice coefficient between the mask and its left-right mirror image. A value of 1 means the mask is perfectly symmetric; 0 means no overlap with its mirror. Dice = 2 * |A ∩ mirror(A)| / (|A| + |mirror(A)|) Because |A| = |mirror(A)| always, this simplifies to: Dice = |A ∩ mirror(A)| / |A|

Usage

[dice, overlap_map] = fmri_dicemirror(mask)

Inputs

MASK: Binary brain mask, vectorized (228453 x 1).

Outputs

DICE: Mirrored Dice coefficient (scalar, range [0 1]).
OVERLAP_MAP: Binary map (228453 x 1): 1 where mask and mirror overlap.

Examples

% Symmetry of left hippocampus mask
mask = fmri_regionmask(57, 1);   % L hippocampus
[d, ov] = fmri_dicemirror(mask);
fprintf('Mirrored Dice: %.3f\n', d)
% Symmetry of a bilateral activation cluster
[d, ov] = fmri_dicemirror(thresh_map);