[Gallstone classification and analysis of their constituents]

Macroscopic classification of gallstones as proposed by the Japanese Society of Gastroenterology is based on the presence of characteristic structures on the cut surface. According to this classification, gallstones can be broadly divided into three types: cholesterol gallstones, pigment gallstones and rare gallstones. This classification is widely accepted in Japan because of its clinical applicability. A more accurate classification requires analysis of the constituents of gallstone. In particular, infrared absorption spectroscopy has been utilized for this purpose because it enables a rapid and easy analysis, requiring only small amounts of sample. In the selection of patients with gallstones for non-surgical treatment, such as ESWL and dissolution therapy, qualitative diagnosis is necessary. With this in mind, we have attempted to produce CT-Profile curves of individual gallstones, depicting changes in CT values assessed along cross-sectional lines passing from the center of the stone to their maximum diameters. This method allowed qualitative diagnosis almost of all gallstones.