A method, medical imaging workstation (1000) and hybrid medical imaging scanner (1100) are provided for defining a region of interest (RoI) for display on at least two medical scan images. When displaying a first medical scan image (740), input data defining a RoI on the image is captured, and stored as at least a first region representation (760). The RoI is displayed on a second medical scan image (750), based on the first region representation (760). Changes to the RoI on the second medical scan image (750) are used to update the first region representation (760). There may be separate region representations (760, 770) associated with each of several medical scan images. The invention may improve the definition of a region of interest, by allowing editing on each of multiple image displays (820, 830, 880) to feed through to all medical scan images.