Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 28, 2015; 21(48): 13403-13410
Published online Dec 28, 2015. doi: 10.3748/wjg.v21.i48.13403
Pancreatic fluid collections: What is the ideal imaging technique?
Narendra Dhaka, Jayanta Samanta, Suman Kochhar, Navin Kalra, Sreekanth Appasani, Manish Manrai, Rakesh Kochhar
Narendra Dhaka, Jayanta Samanta, Sreekanth Appasani, Rakesh Kochhar, Manish Manrai, Departments of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh 160020, India
Suman Kochhar, Department of Radiodiagnosis, Government Medical College and Hospital, Sector 32, Chandigarh 160020, India
Navin Kalra, Department of Radiodiagnosis, Postgraduate Institute of Medical Education and Research, Chandigarh 160020, India
Author contributions: Dhaka N, Samanta J, Manrai M and Appasani S contributed to literature search, first draft and final approval to the manuscript; Kochhar R, Kochhar S and Kalra N contributed to conception, literature search, critical revision of manuscript and final approval to the manuscript.
Conflict-of-interest statement: The authors have no conflict of interests to declare.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Rakesh Kochhar, Professor, Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India. dr_kochhar@hotmail.com
Telephone: +91-9815699565 Fax: +91-172-2744401
Received: May 12, 2015
Peer-review started: May 14, 2015
First decision: June 19, 2015
Revised: July 18, 2015
Accepted: September 30, 2015
Article in press: September 30, 2015
Published online: December 28, 2015

Pancreatic fluid collections (PFCs) are seen in up to 50% of cases of acute pancreatitis. The Revised Atlanta classification categorized these collections on the basis of duration of disease and contents, whether liquid alone or a mixture of fluid and necrotic debris. Management of these different types of collections differs because of the variable quantity of debris; while patients with pseudocysts can be drained by straight-forward stent placement, walled-off necrosis requires multi-disciplinary approach. Differentiating these collections on the basis of clinical severity alone is not reliable, so imaging is primarily performed. Contrast-enhanced computed tomography is the commonly used modality for the diagnosis and assessment of proportion of solid contents in PFCs; however with certain limitations such as use of iodinated contrast material especially in renal failure patients and radiation exposure. Magnetic resonance imaging (MRI) performs better than computed tomography (CT) in characterization of pancreatic/peripancreatic fluid collections especially for quantification of solid debris and fat necrosis (seen as fat density globules), and is an alternative in those situations where CT is contraindicated. Also magnetic resonance cholangiopancreatography is highly sensitive for detecting pancreatic duct disruption and choledocholithiasis. Endoscopic ultrasound is an evolving technique with higher reproducibility for fluid-to-debris component estimation with the added advantage of being a single stage procedure for both diagnosis (solid debris delineation) and management (drainage of collection) in the same sitting. Recently role of diffusion weighted MRI and positron emission tomography/CT with 18F-FDG labeled autologous leukocytes is also emerging for detection of infection noninvasively. Comparative studies between these imaging modalities are still limited. However we look forward to a time when this gap in literature will be fulfilled.

Keywords: Acute pancreatitis, Contrast-enhanced computed tomography, Magnetic resonance imaging, Endoscopic ultrasound, Positron emission tomography scan, Pancreatic fluid collections, Acute necrotic collections, Acute peripancreatic fluid collections, Pseudocysts, Walled-off necrosis

Core tip: Contrast-enhanced computed tomography is widely used imaging modality for the diagnosis and staging of acute pancreatitis due to its excellent capacity to demonstrate early inflammatory changes as well as local complications including fluid collections, However, magnetic resonance imaging may be a better imaging technique due to its, nonionizing nature, higher soft tissue contrast resolution, better safety profile of intravascular contrast media, noninvasive evaluation of pancreatic duct integrity and also has superiority in discrimination of internal consistency of pancreatic collections which is useful in further management plan. Role of endoscopic ultrasound and other newer techniques is still in evolving phase.