New Technology – Combined Use of 3D Contrast Enhanced Endoscopic Ultrasound Techniques

Introduction

While 3D sonography has become established in gynecology, abdominal applications have been mainly restricted to case reports and few studies. However, recent advances in computer technology have supported the development of new systems with motion detection methods and image registration algorithms – making it possible to acquire 3D data without position sensors, before and after administration of contrast enhancing agents. We reported on the first use of 3D imaging of the liver and spleen under real time conditions, using contrast enhanced phase inversion imaging with low mechanical index [1].

The advantages of 3D procedures are clearer visualization of anatomy and topography, visualization of the extension of changes into surrounding tissue with special emphasis on the reconstructed coronary plane, measurement of volumes (also non-symmetrical) or pathologic changes, improved diagnoses (quality of results) through analysis of the third plane, higher quality of results through imaging the surrounding structures with landmarks (quality management), improved examination quality through planning and performing an optimized image acquisition and image documentation, improved acceptance by the referring physician through clearer visualization and therefore fewer follow-up examinations, and demonstration of findings with reference to any desired scan plane (e.g. as part of the daily findings discussion).

Compared to other tomographical imaging methods (e.g. computed tomography, magnetic resonance imaging) ultrasound technology suffers from insufficiently clear documentation of the findings. The single images from real-time sonography resemble the pieces of a mosaic and are assembled into a complex three-dimensional representation of the anatomy in its environmental context, and then recognized in space, solely through the powers of imagination of the investigator. However, an observer not directly participating in the examination will have difficulty sharing in this subjective visualization. Surgeons want a realistic and detailed survey image, where the change in relation to the environment can be evaluated (e.g. segment localization of liver tumors through visualization of the connections to the portal vein branches and hepatic veins).

In recent years contrast enhanced endoscopic ultrasound has been introduced [2] and improved to push the boundries of conventional endoscopic ultrasound. Last year first systems of low mechanical index endoscopic ultrasound features became commercially available [3]. This was the starting point of the contrast enhanced low mechanical index endosonography (CELMI EUS) which allows to visualize contrast enhancing effects in microvessels.

The technique developed first in clinical medicine as a method to discriminate chronic pancreatitis from pancreatic cancer [4] also using the contrast enhancing effect for Doppler spectrum analysis [5]. The investigation proved useful and is still performed in colour Doppler mode with high mechanical index endosonography (CEHMI EUS). In this method, the contrast enhancer (usually Sonovue®) acts as a Doppler flow enhancer for analysis of macrovessels [6].

We report on the latest development in endoscopic ultrasound the combination of CEHMI EUS and CELMI EUS with a 3D reconstruction, which allows unique insights in the vessel structure of lesions.