© 2009 THE AUTHORS JOURNAL COMPILATION © 2 0 0 9 B J U I N T E R N A T I O N A L | doi:10.1111/j.1464-410X.2009.08507.x 1 2009 THE AUTHORS. JOURNAL COMPILATION 2009 BJU INTERNATIONAL Investigative Urology URETERIC RESPONSE TO ABDOMINAL RADIOTHERAPY AND METALLIC DOUBLE PIGTAIL URETERIC STENTS LIATSIKOS et al. Ureteric response to abdominal radiotherapy and metallic double-pigtail ureteric stents: a pig model Evangelos Liatsikos, Iason Kyriazis, Panagiotis Kallidonis, Athanasios Tsamandas*, Dimitrios Karnabatidis † , Georgios Sakellaropoulos ‡ , Nicolaos Flaris § , Christina Kalogeropoulou † , Kriton Filos § , Jens-Uwe Stolzenburg ¶ and Dimitrios Kardamakis † Departments of Urology, *Pathology, † Radiology, ‡ Basic Medical Science, and § Anaesthesiology and Intensive Care, University of Patras, Patras, Greece, and ¶ Department of Urology, University of Leipzig, Leipzig, Germany Accepted for publication 19 December 2008 remained intact. All pigs were exposed to abdominal radiotherapy. The dose rate was ≈5.3 Gy/min and a total radiation dose of 10 Gy was administered. Throughout the treatment the temperature was monitored by the RSs and catheters containing the thermocouples. The pigs were killed at 1 day (four), 7 days (two) and 15 days (two) after treatment, and all ureters examined histologically. RESULTS There was no statistically significant increase in RS and catheter temperature throughout the treatment in any of the treated pigs ( P > 0.05). All histological lesions reported were due to radiation treatment. There were no differences in histology between the ureters containing RSs and controls. CONCLUSION RS usage is unrelated to any increase in stent temperature during abdominal radiotherapy and does not cause any further deterioration in the histology of the ipsilateral ureter, additional to that caused by the initial treatment. KEYWORDS abdominal radiotherapy, full metal, double- pigtail, stent OBJECTIVE To examine the safety and compatibility of full-length metal ureteric stents with abdominal radiotherapy. MATERIALS AND METHODS Four ureteric stents (Resonance TM , Cook Urological, Ireland) (RS) and four RSs specially modified to contain thermocouples were placed unilaterally in eight pigs. The contralateral ureters of the same pigs served as their controls, and contained two polymeric ureteric catheters and two similar specially modified to contain thermocouples, while the remaining four control ureters INTRODUCTION The full metal double-pigtail ureteric Resonance TM stent (RS; Cook Urological, Limerick, Ireland) is an incompressible stent composed of nonmagnetic nickel-cobalt- chromium-molybdenum alloy. RS usage is indicated for the management of patients with malignant, extrinsic ureteric obstruction [1–3]. Studies have shown that it provides satisfactory drainage of the upper urinary tract, even in cases of extrinsic compression sufficient enough to occlude the standard polymeric stents [3]. However, there is limited clinical experience with this novel stent for its safety and compatibility, when it is combined with other anticancer treatments such as abdominal radiotherapy (RT). Considering that high-energy irradiation to metal structures in the body causes low-dose energy back-scatter and absorption, concerns have been raised that RT would result in increase in stent temperature to harmful levels for the ipsilateral ureter [4]. Moreover, the effect of the energy back-scatter on the histology of the stented ureters remains unknown. Thus, we designed an experimental study to assess whether RT was safe in ureters stented with the RS. MATERIALS AND METHODS Eight domestic pigs (20–25 kg) were used for the experiment; the protocol was approved by the Animal Care Committee of our institution. For this experiment four different kinds of ureteric catheters were used; five original RS and two double-pigtail polymeric ureteric (PU) catheters (C-Flex®, Cook Urological) were used as controls to examine the effect of abdominal RT on the histology of the ureter. Also, three RS and two PU catheters were modified to introduce thermocouples into the lumen, to monitor stent temperatures during the procedure. In all, 13 units of precision fine-wire thermocouples (Omega Engineering Inc., Stamford, USA) were placed inside all distal, middle and proximal portions of the modified RS, and in both the distal and proximal portions of the PU catheters (the small diameter of the PU catheter lumen did not allow a third thermocouple to be placed in the middle portion). The modified version of the RS lacked the pigtail design; this was deemed necessary because it was impossible to attach thermocouples to a ‘standard’ RS. The thermocouples inserted in the lumen of the modified RS had their distal ends exiting from the one side of the catheter. To create BJUI BJU INTERNATIONAL