Commentaries on Articles

Current status of endosonography for pancreatic masses

Endosonography ( EUS) plays an important role in the evaluation of pancreatic masses. EUS was developed about three decades ago for the evaluation of pancreas. With the development of EUS as well as CT and MR, the role of EUS has kept on evolving. Following is a brief summary of current status of EUS for pancreatic masses

1. Detection of small lesions: EUS to the best technique to visualize lesions smaller than 2 cm. EUS consistently picks up small lesions not visualized on other imaging modalities. A normal EUS rule out pancreatic cancer with 96% certainty
2. Staging of Pancreatic cancer: The role of EUS in staging of pancreatic cancer has been changing due to inconsistent studies, and rapid evolution of CT scan. EUS has a high pick up rate of portal vein invasion. But it is not good at picking up arterial involvement. In the current scenario, Role of EUS in staging is limited to ruling out portal vein invasion.
3. Tissue diagnosis of Pancreatic cancer: EUS guided FNA and biopsy have a success rate in excess of 90%. EUS guided FNA is safe with a complication rate of 2%, the most feared complication being pancreatitis. EUS guided FNA should be avoided in resectable lesions unless neo-adjuvant protocols are being followed. Tissue diagnosis should be obtained in all patients undergoing palliative chemotherapy
4. Evaluation of CNP: The role of EUS in evaluating cystic neoplasms of pancreas in controversial. EUS features can differentiate pseudocysts from CNP but suffer from low specificity. EUS guided aspiration of cysts and measurement of cyst fluid amylase and CEA helps distinguish pseudocysts from CNP. A high cyst fluid CEA also distinguishes serous from mucinous lesions
5. Mass lesions in chronic pancreatitis: EUS can not differentiate chronic pancreatitis from malignancy based on appearance alone. Even the addition of EUS FNA does not improve the specificity. Newer techniques like contrast enhanced EUS, and elastography have shown initial promise
6. Management of obstructive jaundice: EUS guide biliary stent placement can be used in patients where ERCP does not succeed. A rendezvous procedure has shown good results. EUS guided stent placement can also be done in patients where ERCP can not be performed due to duodenal stenosis
7. Celiac plexus neurolysis: EUS guided CPN has been shown to relieve intractable pain in up to 70% of patients with pancreas cancer. The technique is easy and complication rates are low.
8. Investigational uses: Research is going on for new indications like EUS guide brachytherapy, EUS guided fine needle injection in the tumor, and EUS guided fiducial placement for radiotherapy

Commentary by:

A commentary: Vinay Dhir MD,DNB Head, Dept of Gastroenterology, Asian Inst of Oncology Chief of endosonography, Inst of advanced endoscopy Mumbai