1. A computer-aided diagnostic (CAD) apparatus comprising: a memory configured to store instructions; and at least one processor configured to, upon executing the stored instructions: detect a region of interest (ROI) from an image input from a probe; determine a motion of the probe, matched to a user's manipulation of the probe or a state of the probe, among a plurality of motions of the probe, in response to the ROI being detected; determine a diagnostic intention of a user corresponding to the determined motion of the probe, based on mapping information that maps motions of the probe to diagnostic intentions of the user, wherein the mapping information is pre-stored in the memory; and perform a diagnostic procedure, based on the determined diagnostic intention of the user.