CT abdomen in a 35-year-old with crampy abdominal pain and bloody diarrhoea shows circumferential wall thickening of the transverse colon with 'thumb-printing' (pseudopolyps), loss of haustration in the affected segment, and pericolonic fat stranding. This 'target sign' (stratified wall enhancement) on contrast CT most specifically indicates:

• A Transmural necrosis requiring emergency surgery
• B Carcinomatous infiltration of the colon wall
• C Ischaemic colitis with mural infarction
• D Submucosal oedema and mucosal hyperaemia, consistent with inflammatory bowel disease ✓

Explanation

The target sign (also called 'halo sign') on contrast-enhanced CT — stratified concentric rings of inner mucosal enhancement, middle submucosal hypoattenuation (oedema), and outer muscularis enhancement — indicates benign mural thickening with submucosal oedema, most consistent with IBD (Crohn's/UC) or infective colitis. Ischaemic colitis with infarction shows a monomorphic 'grey' wall without stratification. Carcinoma produces asymmetric focal thickening without a stratified pattern.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.