A medical image annotation system for analyzing a medical image. A plurality of image annotation tools are provided by the image annotation system, each of which is configured to perform, for one or more regions of interest of the medical image, at least a portion of an annotation. A recording module of the image annotation system is configured to record, for each of the regions of interest, interactions which are performed using the image annotation tools. The image annotation system is configured to compute an image annotation complexity metric for each of the regions of interest, based on the recorded interactions. Further, a presentation of the annotation tools by the user interface is indicative of an order, wherein the order is changed in response to the region of interest from which the user input is currently received.
