Endoscopic sonography of the liver--diagnostic application of the echolaparoscope to localize intrahepatic lesions.

To overcome the limitations of ultrasonography and laparoscopy for abdominal diseases, the use of echolaparoscopy was investigated. The instruments used were the prototype echolaparoscope type 1-3 manufactured by Olympus Optical Co., Tokyo, Japan. The first prototype has the external diameter of 12 mm. It consists of an internal shaft connecting to a fixed transducer and a rotating mirror connected to the motor unit and a regular laparoscope to assess the position of the scanning head. The second and third prototypes were versions of the former and had an outer diameter of 10 mm to allow interchangeable use with a regular laparoscope. Transducers used were either of 10 or 7.5 MHz, 7 mm in diameter, and ultrasonic scanning was made by the mirror reflection method. A total of 67 cases with various abdominal diseases were examined on 73 occasions. The merit of the method is its ability to visualize occult lesions in the liver such as cysts and tumors. Differentiation between hepatic hemangioma and hepatocellular carcinoma could be mad without difficulty due to its increased resolution. Furthermore, this method was used as a guide to liver biopsy of occult tumors and decision making in cases of surgical resection of the hepatic lesions.