1. A method for detecting a pulmonary embolism (PE), comprising: receiving original image data of a structure of interest; segmenting the original image data of the structure of interest; rendering two-dimensional images of the structure of interest, wherein the rendering of a two-dimensional image is performed in a single rendering operation, wherein the single rendering operation comprises casting at least one ray through a slab of a plurality of slabs of the original and segmented image data, identifying voxels of both the original and segmented image data that are encountered by the ray, not rendering the original image data encountered by the ray and rendering original image data that corresponds to the segmented image data encountered by the ray, and wherein the voxels considered for the rendering are solely defined by the segmentation and the individual slab through which the at least one ray is cast; and displaying the two-dimensional image to assist a user in identifying an unmarked PE inside the structure of interest.