Abstract: The injector of the invention serves for applying contrast media for X-ray or nuclear spin tomography and has a tube (3), as well as a roller pump (7) surrounded at least partially in peripheral direction by the tube (3) for transporting the fluid from a storage vessel (2) to a cannula. A pressure chamber (10) connected with the interior of the tube (3) through an opening (9) in the tube wall is provided, which has a component (11) adjustable under the effect of the fluid pressure, acting upon a pressure sensor (12).

Abstract: The injector according to the invention serves for applying contrast media for X-ray and nuclear spin tomography and has a tube system (5) consisting of connection tubes (6) and a pump tube (7), as well as several storage vessels (4), each connected via one of the connection tubes (6) as well as a branching piece (8) to a pump tube (7) leading to a cannula. To each connection tube (6) a gas bubble detector (15) as well as a valve (11) are assigned, whereby further to the pump tube (7) a pumping organ (16) reversing the fluid flow from the storage vessel (4) to the cannula is assigned.