COLORECTAL LESIONS - EVALUATION WITH CT COLOGRAPHY

Computed tomographic (CT) colography is a promising technique for diff erentiating malignant or premalignant colorectal disease from benign l esions, In this technique, helical CT data are used to produce reforma tted two-dimensional (2D) CT images and simulated endoscopic images of the colon, Adenomatous polyps 0.7 cm in diameter or larger are easily detected on CT colographic images: A pedunculated polyp is identified by means of its stalk, whereas a sessile polyp appears as a polypoid soft-tissue mass projecting into the air-filled lumen of the colon, Ho wever, flat adenomas (lesions raised less than 2 mm from the surface o f the colon) are difficult to detect with CT colography, In cases of c olorectal cancer, both intraluminal and extraluminal disease can be ev aluated with CT colography, Although CT colography does not allow diff erentiation between hyperplastic and adenomatous polyps, lipomas can b e confidently diagnosed because of their fatty attenuation on reformat ted 2D images, Pseudolesions that can produce false-positive findings at CT colography include the ileocecal valve, retained stool, retained barium, respiratory artifacts, and a stool-filled diverticulum.