>102 F (38,9 C), or leukocytosis there is a Ranson score > 3 or APACHE score > 8 there is no improvement after 72 hours of conservative medical therapy there has been an acute change in status: fever, pain, or shock CT is recommended as a delayed assessment tool in the following situations: acute change in status to determine therapeutic response after surgery or interventional radiologic procedure before discharge in patients with severe acute pancreatitis Abdominal CT should not be performed before the first 12 hours of onset of symptoms as early CT (<12 hours) may result in equivocal or normal findings. CT findings can be classified into the following categories for easy recall: Intrapancreatic – diffuse or segmental enlargement, edema, gas bubbles, pancreatic pseudocysts and phlegmons/abscesses (which present 4 to 6 wks after initial onset) Peripancreatic / extrapancreatic – irregular pancreatic outline, obliterated peripancreatic fat, retroperitoneal edema, fluid in the lessar sac, fluid in the left anterior pararenal space Locoregional – Gerota's fascia sign (thickening of inflamed Gerota's fascia, which becomes visible), pancreatic ascites, pleural effusion (seen on basal cuts of the pleural cavity), adynamic ileus, etc. The principal value of CT imaging to the treating clinician is the capacity to identify devitalised areas of the pancreas which have become necrotic due to ischaemia. Pancreatic necrosis can be reliably identified by intravenous contrast-enhanced CT imaging, and is of value if infection occurs and surgical or percutaneous debridement is indicated. Magnetic resonance imaging While computed tomography is considered the gold standard in diagnostic imaging for acute pancreatitis, magnetic resonance imaging (MRI) has become increasingly valuable as a tool for the visualization of the pancreas, particularly of pancreatic fluid collections and necrotized debris. Additional utility of MRI includes its indication for imaging of patients with an allergy to CT's contrast material, and an overall greater sensitivity to hemorrhage, vascular complications, pseudoaneurysms, and venous thrombosis. Another advantage of MRI is its utilization of magnetic resonance cholangiopancreatography (MRCP) sequences. MRCP provides useful information regarding the etiology of acute pancreatitis, i.e., the presence of tiny biliary stones (choledocholithiasis or cholelithiasis) and duct anomalies. Clinical trials indicate that MRCP can be as effective a diagnostic tool for acute pancreatitis with biliary etiology as endoscopic retrograde cholangiopancreatography, but with the benefits of being less invasive and causing fewer complications. Ultrasound On abdominal ultrasonography, the finding of a hypoechoic and bulky pancreas is regarded as diagnostic of