A medical image diagnosis apparatus and an image data processing apparatus that diagnoses vascular invasion status of a tumor and decides the most appropriate therapy method for the tumor by extracting tumor candidate regions and vascular regions based on extensive volume data derived from covering a therapy target organ, and specifying an adjacent vascular region existing within a prescribed scope from a gravity center of a tumor. The tumor candidate regions and vascular regions are generated as 3D image data or MPR image data for submitting a recommended therapy method for the tumor by adding branch data of the adjacent vascular.