1. To learn about diagnosis of acute pancreatitis.
2. To understand how to apply Atlanta Classification to imaging.
3. To learn about new trends in diagnosis of acute pancreatitis.
Imaging is frequently recommended in patients with acute pancreatitis (AP) to confirm the clinical diagnosis, ascertain the cause, grade the extent and severity of the disease, evaluate severe complications and indicate interventional procedures. The revised 2012 Atlanta criteria for classification of the severity of AP are widely accepted. The challenge for imaging remains to recognise patients suffering from severe or moderately severe AP. But, a direct correlation between clinical severity and morphology may not exist. Imaging is of utmost importance in the 2nd phase of the disease evolution (usually >2 weeks after onset) where AP resolves or evolves secondary to the presence of necrosis and infection, thus morphologic criteria are needed as defined by imaging techniques. It is important to evaluate the extent of necrosis (intrapancreatic, extrapancreatic or both) and also to define if this is sterile or infected. Contrast-enhanced CT is the best technique; however the staging of severity and detection of complications depend on the timing of CT scanning. In the first 24-48 hours, the CT findings of necrosis may be equivocal. In severe AP, unless the patient is critically ill and in need of emergency intervention, the initial CT scan should ideally be obtained at least 72 hours following symptoms onset. As 50% of AP cases are gallstone-related, transabdominal ultrasound is the most common initial radiologic investigation of choice. MRI can better differentiate complex fluid collections from mature pseudocysts and hemorrhagic collections, while MRCP is the best technique to identify pancreatic duct disconnection.