Comparison of abdominal ultrasound, endoscopic ultrasound and magnetic resonance imaging in detection of necrotic debris in walled-off pancreatic necrosis

Endoscopic management of pancreatic collections. Endoscopic Ultrasound Group, Spanish Society of Digestive Endoscopy (GSEED-USE) Clinical Guidelines

Acute pancreatitis is associated with significant morbidity and mortality. It can develop complications such as fluid collections and necrosis. Infection of necrosis occurs in about 20-40 % of patients with severe acute pancreatitis, and is associated with organ failure and worse prognosis. In the past few years the treatment of pancreatic collections has shifted from open surgery to minimally invasive techniques such as endoscopic ultrasound-guided drainage. These guidelines from a selection of experts among the Endoscopic Ultrasound Group, Spanish Society of Gastrointestinal Endoscopy (GSEED-USE) are intended to provide advice on the management of pancreatic collections based on a thorough review of the available scientific evidence. It also reflects the experience and clinical practice of the authors, who are advanced endoscopists or clinical pancreatologists with extensive experience in managing patients with acute pancreatitis.

Early Endoscopic Interventions for Pancreatic Necrosis: Indications, Technique, and Outcomes

Endoscopic transmural drainage is usually performed for symptomatic well-encapsulated walled-off necrosis (WON) that usually develops in the delayed phase (> 4 weeks after disease onset) of acute necrotising pancreatitis (ANP). Endoscopic drainage is usually not advocated in the early (< 4 weeks after disease onset) stage of illness because of the risk of complications due to an incompletely formed encapsulating wall and poor demarcation of viable from necrotic tissue. However, emerging data from expert tertiary care centres over the last few years shows that the early endoscopic transluminal drainage approach is effective and safe. The development of lumen-apposing metal stents and better accessories for endoscopic necrosectomy has fuelled the expansion of indications of endoscopic drainage of pancreatic necrosis. However, early endoscopic drainage is associated with higher rates of adverse events; therefore, careful patient selection is paramount. This article will review the current indications, techniques and outcomes of early endoscopic transluminal drainage in pancreatic necrotic collections.

The Role of Contrast-Enhanced Harmonic Endoscopic Ultrasound in Interventional Endoscopic Ultrasound

Over the last decades, contrast-enhanced harmonic endoscopic ultrasound (CH-EUS) has emerged as an important diagnostic tool for the diagnosis and differentiation of several gastrointestinal diseases. The key advantage of CH-EUS is that the influx and washout of contrast in the target lesion can be observed in real time, accurately depicting microvasculature. CH-EUS is established as an evidence-based technique complementary to B-mode EUS to differentiate solid appearing structures, to characterize mass lesions, and to improve the staging of gastrointestinal and pancreatobiliary cancer. In the last few years, interest has increased in the use of CH-EUS in interventional procedures such as tissue acquisition, tumor ablation, biliary drainage, and the management of pancreatic fluid collections. The aim of this narrative review is to evaluate the available evidence and future expectations of CH-EUS in interventional EUS.

Multiple hidden vessels in walled-off necrosis with high-risk bleeding: Report of two cases

BACKGROUND

Walled-off necrosis (WON), as a local complication of acute necrotizing pancreatitis, is difficult to differentiate from pancreatic pseudocysts (PPC). Imaging modalities such as computed tomography show a lower accuracy than endoscopic ultrasound (EUS) in confirming the diagnosis. EUS-guided cystogastrostomy following direct endoscopic necrosectomy has achieved excellent results and has been regarded as a preferred alternative to traditional surgery. However, high-risk bleeding is one of the greatest concerns.

CASE SUMMARY

Two patients with symptomatic pancreatic fluid collections (PFCs) were admitted to our hospital for EUS-guided lumen-apposing metal stent therapy. The female patient suffered from intermittent abdominal pain and underwent two perioperative CT examinations. The male patient had recurrent pancreatitis and showed a growing PFC. The initial diagnosis was a PPC according to contrast-enhanced CT. However, the evidence of solid contents on EUS prompted revision of the diagnosis to WON. An endoscope was inserted into the cavity, and some necrotic debris and multiple hidden vascular structures were observed. Owing to conservative treatment by irrigation with sterile water instead of direct necrosectomy, we successfully avoided damaging hidden vessels and reduced the risk of intraoperative bleeding.

CONCLUSION

The application of EUS is helpful for the identification of PFCs. Careful intervention should be conducted for WON with multiple vessels to prevent bleeding.

Endotherapy for pancreatic necrosis: An update

Approximately 20% of patients with acute pancreatitis develop pancreatic necrosis. The presence of necrosis in a pancreatic collection significantly worsens the prognosis. Pancreatic necrosis is associated with high mortality and morbidity. In the last few decades, there has been a significant revolution in the treatment of infected pancreatic necrosis. A step‐up approach has been proposed, from less invasive procedures to the operative intervention. Minimally invasive treatment modalities such as endoscopic drainage and necrosectomy, percutaneous drainage, and minimally invasive surgery have recently replaced open surgical necrosectomy as the first‐line treatment option. Endoscopic intervention for pancreatic necrosis is being increasingly performed with good success and a lower complication rate. However, techniques of endotherapy are still not uniform and vary as per local expertise, and there are still many unresolved questions with regard to the interventions in patients with pancreatic necrosis. The objective of this paper is to critically review the literature and update the concepts of endoscopic interventional therapy of pancreatic necrosis.

Prognostic significance of differentiating necrosis from fluid collection on endoscopic ultrasound in patients with presumed isolated extrapancreatic necrosis

Background

Extrapancreatic necrosis is diagnosed on computed tomography (CT) as extrapancreatic changes that are more than fat stranding; both fluid collections and necrosis would have a similar appearance. The aim of this study was to determine the prognostic significance of differentiating peripancreatic necrosis from fluid collection on endoscopic ultrasound (EUS) in patients with presumed isolated extrapancreatic necrosis.

Methods

We carried out a retrospective analysis of prospectively collected data from 36 patients (25 males; age range 19-65 years) with acute pancreatitis (AP) and isolated extrapancreatic necrosis. On EUS, peripancreatic anechoic areas were labeled as peripancreatic fluid collections and peripancreatic heterogeneously echotextured areas as peripancreatic necrosis.

Results

The etiology of AP was alcohol in 16 (44.4%) patients, gallstone disease in 13 (36.1%), and other in 7 (19.4%). On EUS, 25 (69.4%) patients had peripancreatic necrosis and 11 (30.6%) patients had peripancreatic fluid collections. Compared with patients who had peripancreatic fluid collections, patients with peripancreatic necrosis had a significantly higher frequency of pleural effusion (88% vs. 55%; P=0.04), organ failure (OF) (68% vs. 27%; P=0.03), and persistent OF (48% vs. 9%; P=0.03). The patients with peripancreatic necrosis also had a higher frequency of ascites (20% vs. 9%), need for intervention (20% vs. nil), surgery (8% vs. nil) and mortality (8% vs. nil), but these differences were not statistically significant.

Conclusion

Isolated extrapancreatic necrosis on contrast-enhanced CT comprises a heterogeneous group, with patients who show peripancreatic fluid collections on EUS having a less severe disease course compared to patients with peripancreatic necrosis.

Pancreatic fluid collections: What is the ideal imaging technique?

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.