Fig. 4

Flowchart of the proposed EKM–KELM+ algorithm. Feature selection (FS) includes t test and mutual information. In this figure, gray matter (GMV) acts as the main feature (red line), while cerebrospinal fluid (CSFV), white matter (WMV), cortical surface area (Area), and brain network features (BN, constructed by computing the Pearson correlation coefficient using mean and variance of cortical thickness between ROIs) are regard as privileged information (PI), which are help the main feature to train 5 KELM+ classifiers. Any type of feature can be treated as the main feature or PI