Clinically Speaking: Endoscopic Ultrasonography - What, When, How? on East Tennessee Medical News

Clinically Speaking: Endoscopic Ultrasonography - What, When, How?

By: RAMANUJAN "RAM" SAMAVEDY, MD

$Clinically Speaking: Endoscopic Ultrasonography - What, When, How? | Ramanujan \"Ram\" Samavedy, University of Tennessee Medical Center, Endoscopic ultrasonography, EUS, Submucosal lesions, Barrett's esophagus, Gastric cancer, Pancreato-biliary Cancer$

WHAT: Endoscopic ultrasonography (EUS) combines a high frequency ultrasound with an endoscope. This allows imaging of surrounding organs and also the different layers of the GI tract. It allows evaluation of submucosal nodules, local staging of GI malignancies (esophageal, gastric, pancreato-biliary and rectal), non small cell lung cancer and mediastinal lesions. Tissue diagnosis is possible using EUS-FNA and increasingly therapeutic uses are being described.

HOW: The procedure is undertaken like a conventional endoscopy, though the interpretation is more complex and requires additional time. It is safe and has a low complication rate. It is typically done unsedated (rectal) or with conscious sedation. Three types of echoscopes are used – radial array, curvilinear array and high frequency catheter probe. Curvilinear scope allows to direct needle under real time guidance, to aspirate, inject or do core biopsies. The mini probes allow inspection of the layers of the wall and are useful for mucosal and submucosal lesions.

WHEN: Currently, EUS has an established role in the management of the following situations:

submucosal lesions
Barrett's esophagus
gastric cancer and lymphoma
cystic lesions of the pancreas
sampling lymph nodes in the mediastinum and retroperitoneum
uminal GI polyps & cancers
pancreatico-biliary cancer
pancreatitis
fecal-incontinence
evaluating adrenal lesions
celiac neurolysis for pain control

Submucosal lesions–It is the test of choice for assessing the size, margins and the layer of origin. The EUS features correlate with pathology in 77% of cases and FNA confirms histology. Non malignant lesions may undergo EUS surveillance.

Barrett's esophagus–When high-grade dysplasia is noted, EUS helps rule out deeper invasion, concurrent malignancy or nodal metastasis. This helps select suitable patients for endoscopic therapy.

Gastric cancer and lymphoma–T staging accuracy is superior to CT scan, for gastric cancers. For gastric lymphoma, EUS staging assesses extent prior to surgery, impacts choice of therapy and monitors response to therapy.

Cystic lesions of pancreas–EUS with FNA is useful in diagnosis and in treatment of pseudocysts. It can differentiate mucinous, non mucinous and malignant lesions. Mucinous lesions have a higher risk for malignant transformation and often need resection versus close observation.

Luminal GI cancers–EUS is most sensitive in T and regional N staging for esophagus, stomach and rectal lesions. Regional M staging is possible with sampling of malignant ascites, pleural effusion, liver metastasis and celiac nodes.

Pancreato-biliary Cancer–EUS is used in surgical candidates without distant metastasis. It is better than CT and MRI for T and N staging, and is useful in assessing resectability. It is useful in ampullary tumors and bile duct strictures especially with the addition of intraductal EUS. Neuroendocrine lesions can be hard to localize by CT or MRI. EUS can localize them in up to 93% of patients, especially insulinomas. EUS-FNA is particularly useful in lesions < 1cm. Chronic pancreatitis, infiltrating carcinoma and recent acute pancreatitis may lead to false negativity.

Pancreatitis–EUS is more cost effective than ERCP or MRCP as initial test for CBD stones in patients with inconclusive findings. It finds the etiology in idiopathic and acute recurrent pancreatitis in 30-80% of patients, like autoimmune pancreatitis, pancreas divisum, chronic pancreatitis, mucinous tumors etc. Echo features for chronic pancreatitis correlate well with histology and pancreatic function tests, often showing changes which may be absent on other imaging studies.

Fecal incontinence–both EUS and MRI are accurate in defining perianal disease. EUS can identify sphincter defects and EUS evidence of defect closure with surgery correlates with symptom response.

Ramanujan "Ram" Samavedy, MD, is the region's first fellowship trained physician in EUS having completed a Therapeutic Endoscopy Fellowship at St. Luke's Pancreato-biliary Center in Milwaukee, Wisconsin. Samavedy joined University Gastroenterology, P.C. at The University of Tennessee Medical Center in September, 2008, and has already performed nearly 200 EUS procedures.