A system for enabling a user to interactively navigate through a set of slice images, the set of slice images jointly representing an image volume showing an anatomical structure of a patient, the system comprising: - an image data interface configured for accessing the set of slice images; - a user input interface configured for receiving navigation commands from a user input device operable by the user, wherein said receipt of the navigation commands causes the system to switch from a static viewing mode to a navigation mode, wherein the navigation commands are forward or backward navigation commands; - a display processor configured for switching between the static viewing mode and the navigation mode: - in the static viewing mode, generating an output image comprising one slice image (310, 410, 510, 610) of the set of slice images; and - in the navigation mode, replacing the said one slice image in the output image by a volume rendering of a slab (315, 415, 425, 515, 525, 625, 635, 715) of the image volume, the volume rendering being calculated from the slab upon receiving the navigation commands, wherein the slab comprises the one slice image and two or more slice images adjacent to the one slice image; wherein: - the user input interface is configured for enabling the user to provide the forward or backward navigation commands in the navigation mode; and - the display processor is configured for, in response to the forward or backward navigation commands, adjusting a size of the slab within a respective direction in the image volume; wherein the user input device is a computer mouse comprising a mouse button, and wherein the forward and backward navigation commands represent operations of a scroll wheel of the computer mouse in a respective direction while the mouse button is pressed. - an image data interface configured for accessing the set of slice images; - a user input interface configured for receiving navigation commands from a user input device operable by the user, wherein said receipt of the navigation commands causes the system to switch from a static viewing mode to a navigation mode, wherein the navigation commands are forward or backward navigation commands; - a display processor configured for switching between the static viewing mode and the navigation mode: - in the static viewing mode, generating an output image comprising one slice image (310, 410, 510, 610) of the set of slice images; and - in the navigation mode, replacing the said one slice image in the output image by a volume rendering of a slab (315, 415, 425, 515, 525, 625, 635, 715) of the image volume, the volume rendering being calculated from the slab upon receiving the navigation commands, wherein the slab comprises the one slice image and two or more slice images adjacent to the one slice image; wherein: - in the static viewing mode, generating an output image comprising one slice image (310, 410, 510, 610) of the set of slice images; and - in the navigation mode, replacing the said one slice image in the output image by a volume rendering of a slab (315, 415, 425, 515, 525, 625, 635, 715) of the image volume, the volume rendering being calculated from the slab upon receiving the navigation commands, wherein the slab comprises the one slice image and two or more slice images adjacent to the one slice image; - the user input interface is configured for enabling the user to provide the forward or backward navigation commands in the navigation mode; and - the display processor is configured for, in response to the forward or backward navigation commands, adjusting a size of the slab within a respective direction in the image volume;