Figure 9b. Invasive adenocarcinoma. (a) Contrast material-enhanced 2D curved reformatted image with soft-tissue windowing shows an annular-constricting mass with shouldering (arrowheads) involving the sigmoid colon. Cross-sectional 2D views are much more effective than endoluminal displays for depicting invasive mass lesions. (b) Digital photograph from optical colonoscopy shows the proximal aspect of the mass.