A method for investigating a drug depot by means of an imaging method

A method for determining an amount of silver in a drug depot, which is in the form of a layer structure on an inner surface or an outer surface of a plastic bladder (1400), a catheter (900, 1000), or a ureter rail, - wherein the layer structure at least one on the inner surface or the outer surface of the Art bladder (1400) of the catheter (900, 1000), or disposed of ureteral stent silver portion (101, 201, 504, 602, 801, 902, 1002) that - wherein the art bladder (1400), the catheter (900, 1000), or the ureter rail is located, together with the active substance depot in the body of a patient (1401), - wherein the amount of silver in the active substance depot decreases continuously through delivery of the silver to the outside, and wherein the method comprises: - imaging of the patient (1 401) body, in whole or in part, together with the active substance depot therein by means of an imaging method; - determining from the image data of the silver from the image (1410) of the agent depots; - determining the amount of silver in the active substance depot based on the image data, wherein it is determined by the determination of the amount of silver in the active substance depot, when the art bladder (1400), the catheter (900, 1000), or the ureter rail to be replaced together with the active agent depot got to.