title: Computed Tomography Contrast Enhancement Following Renal Cryoablation--Does it Represent Treatment Failure?
abstract: OBJECTIVE
  For minimal invasive treatment of small renal masses, cryoablation has gained popularity. Treatment success is defined as the absence of contrast enhancement on postoperative imaging of the cryoablated lesion, but contrast enhancement does not necessarily equal treatment failure. This present study investigates the proportion of spontaneous resolutions after initial contrast enhancement in relation to cryoablation.
  
  
  METHODS
  Data were collected from a prospectively maintained clinical database containing all patients treated with primary laparoscopic and percutaneous cryoablation between August 2005 and December 2013. All images were evaluated with regard to preoperative aspects and dimensions used for an anatomical classification (PADUA) score, cryolesion size, contrast enhancement pattern, and tissue density.
  
  
  RESULTS
  A total of 107 patients with a biopsy-verified malignant tumor were included in the study. On postoperative imaging, 33 (31%) patients presented with contrast enhancement. Spontaneous resolution was observed in 15 (45%) patients after a mean follow-up time of 14 months. Patients with cryolesions that resolved spontaneously were found to have a less anatomical complex tumor compared to patients with treatment failure (PADUA 7.8 vs 9.5, p < 0.01). A total of seven patients with a PADUA score ≥10 and contrast-enhancing cryolesions were found to have treatment failure. No association was found among body mass index, histology, treatment modality, enhancement pattern, number of applied cryoprobes, and resolution.
  
  
  CONCLUSIONS
  Postoperative contrast enhancement is commonly observed after cryoablation and a large portion of these lesions often resolves spontaneously, thus not representing treatment failure. In patients with a high preoperative PADUA score and postoperative contrast enhancement of the cryolesion, treatment failure or recurrent disease should be suspected.
authors.affiliation: 1 Department of Urology, Aarhus University Hospital , Aarhus, Denmark .
authors.forename: Tommy Kjærgaard
authors.initials: TK
authors.lastname: Nielsen
authors.affiliation: 1 Department of Urology, Aarhus University Hospital , Aarhus, Denmark .
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Østraat
authors.affiliation: 2 Department of Radiology, Aarhus University Hospital , Aarhus, Denmark .
authors.forename: Gratien
authors.initials: G
authors.lastname: Andersen
authors.affiliation: 3 Department of Pathology, Aarhus University Hospital , Aarhus, Denmark .
authors.forename: Søren
authors.initials: S
authors.lastname: Høyer
authors.affiliation: 2 Department of Radiology, Aarhus University Hospital , Aarhus, Denmark .
authors.forename: Ole
authors.initials: O
authors.lastname: Graumann
authors.affiliation: 1 Department of Urology, Aarhus University Hospital , Aarhus, Denmark .
authors.forename: Michael
authors.initials: M
authors.lastname: Borre
mesh_terms: D000368:Aged; D001706:Biopsy; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D003287:Contrast Media; D003452:Cryosurgery / Q000379:methods*; D016208:Databases, Factual; D005260:Female; D006801:Humans; D007668:Kidney / Q000601:surgery; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D010535:Laparoscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure; D016896:Treatment Outcome; D047368:Tumor Burden
chemical_list: D003287:Contrast Media