Masao Araki

Present Status and Future Perspectives of Endoscopic Ultrasonography-Guided Fine-Needle Aspiration

Since endoscopic ultrasonography (EUS) for gastroenterological diseases was first reported in 1980, EUS has widened its indications and has become an indispensable examination in the clinical field. However, it had been necessary to obtain cytology or histology also because of unsatisfactory EUS diagnostic accuracy. Then, the first report of EUS-FNA (fine-needle aspiration) was made by Vilmann and Grimm in 1992. After its introduction, EUS-FNA has widened its indication with high accuracy and a low complication rate in the clinical field. Also, the EUS-FNA technique has been improved as to the size of the needle, stroke, number of passes, and negative aspiration pressure. Furthermore, pseudocyst drainage, celiac trunk neurolysis, etc., have been established and immunotherapy such as dendritic cell injection and gene therapy has been applied. EUS-FNA seems to be a promising technique and will improve day by day.

NEW APPLICATION OF NARROW BAND IMAGING FOR CHOLANGIOPANCREATOSCOPY

The usefulness of narrow band imaging (NBI), which is based on the principle that the depth of light penetration depends on its wavelength, has been accepted for evaluating malignant or benign lesions in the pharynx, the upper, and lower gastrointestine. The purpose of the present paper was to investigate NBI for diagnosing biliopancreatic disease. Using NBI it has become easy to detect the surface microstructure of biliary mucosa and subjacent vascular network of the bile duct, and inflammatory scarring stenosis is visualized as a whitish scar and multiple inflammatory red spots. However, bile duct cancer was detected as a stenosis with abnormal subjacent vessels and irregular surface. Concerning pancreatic duct, NBI has clearly shown vascular network and spreading of branch‐type intraductal papillary mucinous neoplasm to the main pancreatic duct. In contrast, bile juice has been detected as red fluid and bleeding as black red. Therefore, it is important to flush the biliary system before observing with NBI.

CLINICAL USEFULNESS OF NEWLY DEVELOPED ELECTRONIC 360° RADIAL ENDOSCOPIC ULTRASONOGRAPHY

After the development of the mechanical radial scanning echoendoscope by Olympus Medical Systems (Tokyo, Japan), endoscopic ultrasonography (EUS) has become an indispensable examination in the clinical fields. Although mechanical radial EUS has no Doppler function because of its scanning method, Olympus Medical Systems developed a new electronic 360° radial EUS in 2003. Newly developed electronic radial EUS provides better penetration, fewer artifacts, color Doppler and power Doppler function, and tissue harmonic imaging. Its maneuverability is nearly the same as conventional mechanical radial EUS. With Doppler function it is easy to differentiate solid tumors such as pancreatic cancer, islet tumor etc., and to diagnose vascular invasion. Although there are some problems, electronic radial EUS has a promising future and it is believed that electronic radial EUS will become the standard model for the next generation of EUS equipment in imaging diagnosis.