Three-dimensional endoscopic ultrasound of the esophagus

Background: The aim of this study was to develop a technique for three-dimensional endoscopic ultrasound of the esophagus based on standard ultrasonic images. Methods: Endoscopic ultrasound was performed in five esophageal cancer patients using a high-resolution miniprobe (360°, 12.5 MHz). For acquisition of three-dimensional data sets, the miniprobe was attached to a stepping motor that enabled ECG-triggered withdrawal of the transducer. Three-dimensional images were reconstructed from serial transverse sections on a PC-based 3D work station. Results: Twelve volume scans were obtained in five patients with esophageal cancer. The system enabled the acquisition of accurate three-dimensional ultrasound data within 30– 50 s. Computed image processing allowed us to display the data in transverse, longitudinal, and oblique sections, or as a 3D reconstruction. Three-dimensional imaging provided accurate visualization of the tumor and surrounding structures in all cases. The tumor stage was determined correctly in four of five patients. Longitudinal scan planes and 3D views improved the assessment of longitudinal tumor infiltration and the spatial relation of the tumor to relevant mediastinal structures. Conclusion: This study shows that three-dimensional endoscopic ultrasound of the esophagus is technically feasible. The technique allows the assessment of local tumor spread in previously unattainable scan planes and 3D views. This promising preliminary experience should encourage further exploration of this method.