Fig. 4
From: Electronic cleansing of tagged residue in CT colonography: what radiologists need to know
Persistent tagged residue on a flat lesion in the ascending colon. a On the axial 2D image before EC, the soft tissue plaque-like lesion is coated by a thin layer of hyperdense tagged residue (arrow). Tagged residual fluid is seen on the dependent colonic wall (arrowhead). b After EC, the layer of contrast media remains on the flat lesion (arrow) while the residual fluid was removed. Note that “contrast coating” of polyps has been reported to aid in polyp detection. Focal deposits of contrast media are therefore intentionally not removed by EC