Imaging the gallbladder: a historical perspective. After Wilhelm Conrad Roentgen's discovery of the X-ray in 1895, it was initially thought that gallstones could not be visualized. Surgeons relied solely on the clinical examination to detect biliary disease. Today, no evaluation of the gallbladder would be complete without the performance of an imaging study. Radiology has gone through several eras in the imaging of gallstones. The plain film era, 1895-1924, was characterized by techniques that improved soft-tissue detail, allowing better detection of radiopaque stones. The contrast media era, 1924-1960, was initiated by the invention of IV cholecystography. In 1925, oral cholecystography was developed. During the era of expanding technology, 1960-1979, percutaneous transhepatic cholangiography, scintigraphy, and sonography came into use. The therapeutic era began in the 1980s. 