Abstract: A method and imaging system for contouring medical images is described. The method comprising: receiving at least one input 2D image slice, from a set of two-dimensional (2D) image slices constituting the 3D image, and at least one set of data representing an input contour identifying one or more structures of interest in the 3D image within the at least one input 2D image slice; receiving at least one selected target image slice, from the set of the 2D image slices; and predicting target contour data for the selected target image slice that identifies at least one of the same one or more structures of interest within the target image slice, based on one or more of the received input 2D image slices and the data representing an input contours.