All examinations were performed on multiple detector CT scanners (Somatom Definition AS 128 and Somatom Definition Flash 128, Siemens AG, Wittelsbacherplatz 2, DE-80333 Muenchen Forchheim, Germany) within 24 h after AP onset and admission. The following standard CT protocol for abdominal imaging was applied: For opacification of the gastrointestinal tract, 2000 mL of positive radiocontrast agent was administered orally, and 150 mL nonionic contrast medium (300 mg I/mL iopromide [Ultravist, Bayer Schering Pharma AG,Berlin Germany] or iomeprol [Iomeron, Bracco Altana Pharma, Milano, Italy]) was power-injected IV at a rate of 3 mL/s in all patients. Portal venous phase scans of the abdomen in the craniocaudal direction were acquired and reconstructed in the axial plane with a slice thickness of 5 mm.