A multimodal organ modelling system (MMOMS) is an interactive medical visualisation workstation which uses image data from one or more imaging modalities plus additional medical knowledge, e.g. from a digital atlas to produce and interpret 2D, 3D and time sequence images. The MMOMS may give ‘added-value’ to diagnosis and planning of therapy either through features which can only be derived from more than one image modality or by those which can be better visualized or made more directly quantifiable than through the interpretation of a single modality.