A method is disclosed for post-processing of a 3D image data record which has been recorded by way of an imaging tomographic appliance of a body area, and covers at least one hollow organ which is at least partially filled with contrast agent. An imaging apparatus is also disclosed. In the method, an automatic three-dimensional edge detection process is carried out in the 3D image data record in order to determine transitions between areas which have contrast agent and a wall of the hollow organ as boundary surfaces. A weighted high-pass filtering process is carried out at right angles to the boundary surfaces and leads to removal of the areas which have contrast agent and in which process areas around the transitions are given a lower weighting than areas which are further away from the transitions. After low-pass filtering in the areas around the transitions, a 3D image data record is produced from which the areas which are filled with contrast agent are eliminated, without image artifacts being produced at the transitions to the wall of the hollow organ. The method can be used in particular for virtual bowel cleaning in virtual colonography.