The best indication of debris containing collections on CT is increased frequency of fat density globules within the collections. The absence of fat globules within a collection does not exclude the possibility of necrosis; however, the presence of fat globules suggests a debris- containing, necrotic collection [26]. CT abdomen and pelvis with IV contrast is useful for detection of an infected collection, which has the imaging features of an enhancing wall and gas bubbles within the collection. However, air bubbles may not be seen with an infected collection, and the diagnosis is ultimately made by fine-needle aspiration and fluid analysis. CT abdomen and pelvis with IV contrast may also be helpful in the detection of a fistulous communication between a fluid collection and an adjacent bowel loop. CT abdomen and pelvis without IV contrast can help diagnose the presence of large fluid collections that may be symptomatic and may help in preprocedural planning if percutaneous drainage or cyst gastrostomy is contemplated. Smaller fluid collections may sometimes be difficult to discern between fluid-filled bowel loops on an examination performed without IV contrast. Fluid collections are identifiable on a CT abdomen and pelvis examination performed with IV contrast and adding a noncontrast phase by performing CT abdomen and pelvis without and with IV contrast does not add additional diagnostic information. MRI Abdomen The contents of pancreatic and peripancreatic collections can be most accurately assessed by fluid sensitive MRI sequences on MRI abdomen without IV contrast with MRCP. T2-weighted imaging provides superior soft-tissue differentiation when compared with CT and allows for more consistent quantification of debris. As such, MRI is more useful for predicting whether these collections can be drained by endoscopic, percutaneous, or surgical drainage procedures.
Acute Pancreatitis. The best indication of debris containing collections on CT is increased frequency of fat density globules within the collections. The absence of fat globules within a collection does not exclude the possibility of necrosis; however, the presence of fat globules suggests a debris- containing, necrotic collection [26]. CT abdomen and pelvis with IV contrast is useful for detection of an infected collection, which has the imaging features of an enhancing wall and gas bubbles within the collection. However, air bubbles may not be seen with an infected collection, and the diagnosis is ultimately made by fine-needle aspiration and fluid analysis. CT abdomen and pelvis with IV contrast may also be helpful in the detection of a fistulous communication between a fluid collection and an adjacent bowel loop. CT abdomen and pelvis without IV contrast can help diagnose the presence of large fluid collections that may be symptomatic and may help in preprocedural planning if percutaneous drainage or cyst gastrostomy is contemplated. Smaller fluid collections may sometimes be difficult to discern between fluid-filled bowel loops on an examination performed without IV contrast. Fluid collections are identifiable on a CT abdomen and pelvis examination performed with IV contrast and adding a noncontrast phase by performing CT abdomen and pelvis without and with IV contrast does not add additional diagnostic information. MRI Abdomen The contents of pancreatic and peripancreatic collections can be most accurately assessed by fluid sensitive MRI sequences on MRI abdomen without IV contrast with MRCP. T2-weighted imaging provides superior soft-tissue differentiation when compared with CT and allows for more consistent quantification of debris. As such, MRI is more useful for predicting whether these collections can be drained by endoscopic, percutaneous, or surgical drainage procedures.