Radio-contrast enhancement of urinary tract stones

Most urologists treating stone disease with any method (ESWL, PCL, URS) have encountered problems of poor stone visualization with fluoroscopy. This difficulty to localize urinary tract (UT) stones or fragments may result in incomplete stone extraction, prolonged surgery and increased risk of recurrence and post-operative complications. We have sought and found means to increase the radioopacity of mineral UT stones by a simple pre-operative perfusion technique. The capacity of radioopacification has first been demonstrated in in vitro incubations of fragments of human mineral stones with aqueous solutions of barium, of the lanthanides and of the two natural actinides. Most of the incubations led to considerable radio-contrast enhancement and heavy metal incorporation, measured by X-ray fluorescence analysis. Dogs with implanted human stone fragments were used as an in vivo model. The UT were perfused through a retrograde pyelic catheter with heavy metal salts solutions, the ensuing radioopacification of the implanted UT-stones was estimated by abdominal radiographies and the metal incorporation was measured on the retrieved stones. Considerable radioopacity enhancement together with heavy metal incorporation was observed for the following elements: Sr, Ba and the lanthanides Gd and Yb. The pathological evaluation of the urothelial linings from animals treated with lanthanide salt showed no toxic effects.