title: Covered retrievable prostatic urethral stents: feasibility study in a canine model.
abstract: OBJECTIVE
  To evaluate the feasibility of use of a covered, retrievable prostatic urethral stent and to determine urethrographic and histologic changes in the prostate induced by the stent in a canine model.
  
  
  METHODS
  Polytetrafluoroethylene-covered retrievable nitinol stents were placed in the normal prostatic urethras of 13 dogs. The stents were removed 8 weeks after placement. The dogs were killed immediately after stent removal (group 1, n = 5) or 8 weeks after stent removal (group 2, n = 8). Retrograde urethrograms were obtained every 2 weeks after stent placement and after stent removal in dogs that had not been killed. The histologic changes in the prostate were compared between the two groups.
  
  
  RESULTS
  Stent placement was technically successful in all dogs. In two dogs, a second stent was placed because of migration of the first stent into the urinary bladder. Stent removal was successful in 12 dogs. One stent was removed in its expanded state. On follow-up urethrograms, dilation of the prostatic urethra persisted until animals were killed (P = .14). The mucosal hyperplasia that occurred after stent placement at both ends of the stent gradually decreased after stent removal (P < .001). Histologic examination revealed prostate glandular atrophy and periurethral fibrosis, which did not differ between the two groups (P = .72 and P = .83, respectively). Papillary hyperplasia of the uroepithelium and submucosal inflammatory cell infiltration was decreased significantly in group 2 compared with group 1 (P = .002, P = .011, respectively).
  
  
  CONCLUSIONS
  Covered retrievable prostatic urethral stents seem to be feasible for use in the canine prostatic urethra. The stent-induced prostatic urethral dilation and prostate glandular atrophy persist until 8 weeks after stent removal.
authors.affiliation: Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-2dong, Songpa-gu, Seoul, Republic of Korea.
authors.forename: Chang Jin
authors.initials: CJ
authors.lastname: Yoon
authors.forename: Ho-Young
authors.initials: HY
authors.lastname: Song
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Shin
authors.forename: Chul-Woong
authors.initials: CW
authors.lastname: Woo
authors.forename: Jae-Y
authors.initials: JY
authors.lastname: Ro
authors.forename: Hyung Keun
authors.initials: HK
authors.lastname: Park
authors.forename: Hyun-Ki
authors.initials: HK
authors.lastname: Yoon
mesh_terms: D000818:Animals; D020878:Device Removal / Q000379:methods*; D004285:Dogs; D004867:Equipment Design; D005240:Feasibility Studies; D008297:Male; D023421:Models, Animal; D011467:Prostate; D011859:Radiography; D015607:Stents; D014521:Urethra / Q000000981:diagnostic imaging / Q000601:surgery*