The present invention provides a system and a method for simultaneously modifying one or more angles of cross-sections in one or more cross-sectional images or stacks of images of a 3D volume. A plurality of viewports is displayed to a user. Each viewport includes a 2D cross-sectional image or stack of images and all 2D images or stacks of images are displayed simultaneously. One or more viewports may also include a control line representative of an angle of cross-section or image plane of a 2D image or stack of images displayed in another viewport. If a control line is moved in a selected viewport, the angle of cross-section or image plane of a 2D image or stack of images in another viewport is accordingly altered simultaneous with such control line movement.