The invention relates to evaluating medical image information, in particular physical properties of an object (32). When preparing a surgical procedure e.g. a minimally invasive procedure, it may be beneficial to plan the procedure in detail before starting the operation. Thus, obtaining precise information about physical properties of an object (32), e.g. a diameter value (34, 36) of an anatomical structure may be beneficial. Accordingly, a method and a system for determining a physical property (34, 36) of an object (32) is provided, which employs local object context information (38) for determining a local physical property of the object (32).