[Radiation absorption, water content and contrast medium impregnation of gallstones].

Gallstones extracted by surgery were examined for CT density, which was compared with the x-ray-film, floating performance and chemical analysis of the stones. So far, the water content of the biliary concrements--14% on the average--has not been given much attention. Drying will considerably reduce the density; examination of dried gallstones yields a false picture of direct ray absorption. Pure cholesterol stones do not float in water, and they show positive values on Hounsfield's scale (+30--+60). The article discusses the question whether CT is suitable for effecting a better selection of gallstone patients who can be treated by drug therapy.