Thank you for answer... By loading .mat files I get as below: roi=load('VOI_rV6_sum-LH.mat'); >> roi.xY ans = def: 'cluster' xyz: [3x1 double] spec: [4x4 double] XYZmm: [3x4608 double] w: [1x4608 uint8] name: 'sum_V6_LH' ...I'll be looking for spm_vol and others. Riccardo