[The first 25 years of digestive radiology].

The first medical radiological attempts used the natural contrasts of the human body: bones of the limbs, intra-alveolar air of the lung; but as regards the abdomen, one could only observe gases or eventually calcified calculi. Whence the idea of a product opaque to the X-rays, not toxic, in order to obtain an internal cast of the various segments of the digestive tractus, making them thus visible by radiology. After little demonstrative trials of opaque sounds and capsules containing opacifying substances, there was an orientation towards the bismuth salts: sub-nitrate and carbonate generally used as therapeutical agents. In all the countries, engineers and physicians thrived to fit the equipment and experiment techniques of serial radiographies. Rieder, a radiologist from Munich perfected in 1905 the "meal" wearing his name (gruel of food and bismuth salts) adapted nearly everywhere. The radiological technology developed itself accordingly, creating progressively performant material. Finally, Paul Krause from Bonn and his team preconized in 1910 the use of insoluble baryum sulfate in watery suspension of which the purification was from now on assured. This product will be universaly used as a "gruel" or a "baryted milk" for the aesophago-gastro-duodenal transit and as a baryted enema for the examination of the colon.