Intraoperative Real-Time Ultrasound-Elastography of the Pancreas: A Method for ‘Visual Palpation’

Paolo Abitabile, MD, Christoph A Maurer, Prof. Department of Surgery, Kantonsspital Liestal, CH-4410 Liestal, Switzerland

Objective
First experience with intraoperative real time ultrasound-elastography (USEG) in pancreatic surgery is reported.

Methods
Real-time elastography is based on standard diagnostic ultrasound equipment. Backscattered signals along the longitudinal axis of the ultrasound transducer are analysed. The time-delay at compression and decompression (expansion) of tissues is measured and color coded. A stiffer and harder tissue element generally experiences less elasticity than a softer one. Elastic tissue (green) can be visually distinguished from non-elastic (blue) tissue. The elasticity index (EI) determines the relative elasticity of the area of interest compared to the elasticity of the surrounding tissue area.

Results
In two patients with painless jaundice and pancreatic double duct sign at ERCP, but without cholelithiasis, the presence of a periampullary cancer was for debate. Even though all additional investigations (CT, MRI, endoscopy, brush cytology, CA 19.9) were not suspicious for malignancy, we preferred to force diagnosis by exploratory laparotomy, intraoperative ultrasound and elastography.
In patient 1, USEG revealed homogeneous, soft, mainly green colored (EI=0.38) pancreatic tissue with exception of the periampullary area: a well-demarcated, elastographically blue area (EI=0.09) of 1.2cm in diameter was identified, that was 4.2 times harder than the other pancreatic tissue and corresponding to a palpable small intrapancreatic node. This area was not clearly depicted by B-mode sonography due the biliary drain, but was also identified by the lack of contrast enhancing.
In patient 2, diffuse induration of pancreatic head was found. USEG showed a homogeneously blue pancreatic head that was 4 times harder (EI=0.07) compared to a homogeneously green pancreatic body and tail (EI=0.28).
In both cases, USEG findings were easily and repeatedly reproducible.
Pancreatic head specimens revealed a small periampullary ductal adenocarcinoma (patient 1) and a diffuse ductal adenocarcinoma of pancreatic head (patient 2), respectively.

Conclusions
USEG is a promising new technology that permits to visualize tissue elasticity and to quantify relative tissue consistency. USEG seems to be easy, safe and reliable. Intraoperative USEG might help to detect solid tumors of the pancreas and to make appropriate intraoperative decisions in pancreatic surgery.
 


Session: Emerging Technology
Program Number: ET008

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