Endosonography and endoscopic magnetic resonance imaging.

Endosonography is an important modality for the diagnosis and staging of oesophageal, gastric, colorectal and pancreatobiliary malignancy. It is also recognized as a reliable method for the evaluation of submucosal tumours of the gastrointestinal tract, for differentiating benign lesions from giant gastric folds, and for the localization of pancreatic endocrine tumours. The latest development, that of endosonographic fine-needle aspiration, provides for the cytological diagnosis of gastrointestinal tumours. This new technique may also be used for endoscopic therapy. High-frequency probes can be used to make a more accurate diagnosis of superficial carcinoma of the gastrointestinal tract, for three-dimensional imaging of gastrointestinal tumours and for intraductal ultrasonography of the bile duct and pancreatic duct. Endoscopic magnetic resonance imaging provides information not obtainable with endosonography or other modalities. It has high potential in the diagnosis and staging of gastrointestinal and pancreatobiliary tumours.