Digital gastrointestinal imaging: the effect of pixel size on detection of subtle mucosal abnormalities.

Abstract

Five radiographs of double-contrast colon examinations demonstrating subtle mucosal changes of inflammatory bowel disease and five radiographs of healthy colonic mucosa were selected and digitized to four levels of resolution. Pixel sizes of 0.1 mm, 0.2 mm, 0.4 mm, and 0.8 mm were used. Ten radiologists interpreted the images, which were displayed on laser-printed film. Analysis of variance with repeated measures was performed and receiver operator characteristic curves were determined. The results demonstrate that (a) the sensitivity in detecting subtle mucosal abnormalities improved as the resolution improved, with the best sensitivity at the highest resolution; (b) more experienced readers detected details well even at the poorer levels of resolution; (c) the resolution necessary for sucessfully evaluating the colonic mucosa was lower than expected; and (d) given low noise levels, the matrix size used in conventional television fluoroscopy would be adequate for mucosal evaluation.