Fluid Collections Associated With Acute Pancreatitis: A Pictorial Essay  Aysel Türkvatan, MD, Ayşe Erden, MD, Mustafa Seçil, MD, Mehmet A. Türkoğlu, MD  Canadian Association of Radiologists Journal  Volume 65, Issue 3, Pages 260-266 (August 2014) DOI: 10.1016/j.carj.2013.08.003 Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 1 Evolution of a pseudocyst. Interstitial oedematous pancreatitis in a 64-year-old woman with gallstones. (A) A contrast-enhanced computed tomography (CT) image, obtained at admission, revealing acute peripancreatic fluid collection (F) predominantly collected in the lesser sac. (B) An ultrasound image of the same patient, obtained 5 weeks after the CT, showing the development of a pseudocyst (Ps) in the lesser sac. P = pancreas. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 2 (A, B) Multiple pancreatic pseudocysts in a 41-year-old woman with biliary acute pancreatitis. Contrast-enhanced computed tomography images obtained 6 weeks after the onset of acute attack, revealing pseudocysts (Ps) in the mediastinum, pancreatic body, and left anterior pararenal space. The wall of the mediastinal pseudocyts is thick and irregular, and has increased contrast enhancement, which indicates infection. There are bilateral pleural effusion and ascites. A dilatation of the main pancreatic duct (arrow) due to compression of the pseudocyst is also seen in image B. P = pancreas. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 3 Pancreatic pseudocysts (Ps) in a 45-year-old man known with chronic alcohol abuse. An axial T2-weighted magnetic resonance image with fat suppression obtained 6 weeks after the onset of acute attack, revealing 2 well-defined, homogenous hyperintense fluid collections, with a fibrous capsule. St = stomach. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 4 An infected pseudocyst (Ps) in a 31-year-old woman with biliary acute pancreatitis. Contrast-enhanced computed tomography image obtained 8 weeks after the onset of acute attack, revealing an encapsulated, rounded fluid collection with septations and a thick and irregular wall of increased contrast enhancement. Note air bubbles within the pseudocyst. P = pancreas. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 5 Pancreatic parenchymal necrosis with peripancreatic fat tissue necrosis progresses to acute necrotic collection (ANC) in a 56-year-old man with gallstones. Unenhanced (A) and contrast-enhanced (B) computed tomography (CT) images obtained 3 days after the onset of acute attack, revealing a nonenhancement of the entire pancreatic gland (P) that corresponds to pancreatic necrosis; inflammatory stranding and necrosis of the peripancreatic fat tissue (white arrows), a small amount of peripancreatic fluid and gallstones in the gallbladder (black arrow) are also seen. Note high-attenuation content of the gallbladder due to a previous endoscopic retrograde cholangiopanreatography examination. (C) A follow-up contrast-enhanced CT image, obtained 24 days after the onset of an acute attack, showing an ANC, which replaced the entire pancreatic gland, contained multiple necrotic fatty tissue and a solid necrotic debris. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 6 Necrotizing acute pancreatitis in a 45-year-old man with gallstones. (A) Contrast-enhanced computed tomography (CT) images obtained 3 weeks after the onset of an acute attack, revealing an acute necrotic collection (ANC) that contained solid necrotic debris. (B, C) A follow-up contrast-enhanced CT images obtained 6 weeks after the onset of an acute attack, showing anencapsulated walled-off necrosis (WON [white arrow]) that evolved from the ANC, containing pancreatic and/or extrapancreatic solid necrotic debris; note a hyperdense stone (black arrow) in the common bile duct in image B. (D) Solid necrotic debris (white arrows) within the WON better seen in the ultrasound image. P = pancreas. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 7 Disconnection of the pancreatic duct in a 49-year-old man with prior episodes of alcoholic pancreatitis. Contrast-enhanced computed tomography image obtained 3 weeks after the onset of acute attack, revealing necrosis (arrow) of the entire width of the proximal body of the pancreas (P), which communicates with a large fluid collection (F). Disconnected pancreatic duct was proved at surgery. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 8 Necrotizing acute pancreatitis in a 57-year-old man known with chronic alcohol abuse. Contrast-enhanced computed tomography image, obtained 3 weeks after the onset of acute attack, revealing an acute necrotic collection (ANC) contained solid necrotic debris. Air bubbles and air-fluid level are indicative of infection. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 9 Pancreatic necrosis (>75%) in a 68-year-old woman with gallstones. (A) Contrast-enhanced computed tomography (CT) images at the portal venous phase, obtained 3 days after the onset of an acute attack, showing full-width necrosis (N) of the pancreatic neck, body, and proximal tail; parenchyma of the distal tail is seen to enhance normally. Contrast-enhanced CT images obtained 4 weeks (B) and 8 weeks (C) after the onset of an acute attack, showing a walled-off necrosis (WON) contained necrotic fatty tissue and solid necrotic debris. (C) A cystogastrostomy catheter within the WON (arrow) is seen in image. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 10 Walled-off necrosis (WON) in a 56-year-old woman with biliary acute pancreatitis. (A) Contrast-enhanced computed tomography (CT) image, obtained 6 weeks after the onset of an acute attack, showing a WON (arrow) with an enhanced wall and containing a necrotic fatty tissue. Axial T1-weighted (B) and T2-weighted (C) magnetic resonance image obtained 1 week after the CT, revealing the complex nature of this fluid collection (WON [arrow]). Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 11 An infected walled-off necrosis (WON) in a 56-year-old woman with biliary acute pancreatitis. (A, B) Contrast-enhanced computed tomography images obtained 5 weeks after the onset of acute attack, showing a large multiloculated WON (arrow) with enhanced irregular thick wall and containing solid necrotic debris, and extending to the right abdomen. Air bubbles in the fluid collection indicate infection. P = pancreas. Canadian Association of Radiologists Journal 2014 65, 260-266DOI: (10.1016/j.carj.2013.08.003) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions