Impact of preoperative endoscopic ultrasound in surgical oncology

Conventional endoscopic ultrasound „ Linear versus radial systems Endoscopic ultrasound (EUS) with f lexible endoscopes is an important diagnostic and therapeutic tool, especially for the local staging of gastrointestinal (GI) cancers, the differentiation between benign and malignant tumors, and interventional procedures, such as biopsies and stent applications. Flexible endoscopy was primarily based on radial scanners, which are attached at the tip of an endoscope. The usual 5–12-MHz scanners produce a single-plane 360° image in the immediate proximity. Most studies investigating the role of flexible EUS have been conducted with these radial scanners (Figure 1). Later on, a linear (longitudinal) ultrasound array was introduced and entered the clinical setting. In accordance with the radial scanner, it uses comparable frequencies between 5 and 10 Hz. A major advantage is the possibility to allow fineneedle biopsies under real-time guidance with complete visualization of the needle (Figure 2). In addition, the linear array allows duplex and power Doppler sonography. It remains controversial whether the radial scanner offers an increased anatomical orientation compared with the linear arrays.