1. CT scout view of abdomen, AP projection

A scout view is a preliminary image obtained prior to performing the major portion of a particular study. There may be one or more reasons to get a scout view: to make sure the region of interest is included in the field of view, to check the exposure technique, or as a baseline prior to administration of contrast material.

In the case of a CT study the scout view is used to plot the locations where the subsequent slice images will be obtained. The CT machine can produce this radiographic type image.

Most of the abdominal organs and structures are of soft tissue (water) density, and so the images of contiguous structures merge with each other. We take advantage of any inherent differences in density in some structures to discern them; for example, air in the bowel lumen or the thin sleeve of fat surrounding the psoas muscles allow us to delineate these structures from the soft tissue shadows surrounding them.

If you study this image carefully you will observe that the lumens of the ascending colon and urinary bladder are slightly denser than soft tissue, because this patient received both intravenous contrast (which was filtered from the blood by the glomeruli to be excreted in the urine) and oral contrast prior to obtaining this scout film.