<prompt> Radiological signs of crohns disease:String sign of cantorPipestem appearancePseudo polypBackwash ileitis  <response>: Ans, A. String sign of cantor Characteristic Radiological features of Crohns disease or Regional Enteritis:Terminal ileum is the MC siteGranularity asymmetrical involvement with skip lesionUlcer: Apthous ulcer fissure ulcerCobblestone pattern serpiginous longitudinal transverse ulcer separated by areas of edemaRigidity of mesenteric boarder and pseudosacculation of antimesenteric boarder Omega signWide gapping of bowel loops due to thickening of bowel wallStricture : long segment string .sign if cantorDoule Halo configuration is seen on CT scan Radiology review manual by wolfgang Dahnert 5th809 Characteristic features of ulcerative colitisCollar button ulcerDouble Trackingflongitudinal submucosal ulceration over several centimeterSymmetrical involvement of colonRectum involved in 95 of casesThumbprinting due to mucosal oedemBlunting of haustral fold Pipestem appearanceInflammatory palypBackwash ileitis: In ulcerative colitis when whole colon involved, the inflammation extends 1-2 cm into terminal ileum in 10-20 cases called Backwash ilitis . 