title: Contrast enhancement on computed tomography after renal cryoablation: an evidence of treatment failure?
abstract: OBJECTIVE
  Renal cryoablation has gained popularity as a treatment option for localized renal masses. Treatment success is typically defined by the absence of contrast enhancement on follow-up imaging. We investigate the evolution of lesions that demonstrate contrast enhancement on CT after renal cryoablation.
  
  
  METHODS
  Retrospective review of records of laparoscopic and percutaneous cryoablation (LCA and PCA) was performed, identifying records with postoperative radiographic enhancement. Imaging studies were reviewed and radiographic (pre- and post-contrast Hounsfield units, pattern and location of enhancement) and clinical data including follow up were collected.
  
  
  RESULTS
  One hundred and seventy-two cryoablation procedures were analyzed. Of these, 30 (17.4%) showed enhancement on follow-up CT. In 28 cases, contrast enhancement was demonstrated on the first postoperative study. Seven patients underwent salvage treatments. Spontaneous resolution of enhancement was noted in 17 (56.7%) cases. No association was found between enhancement pattern (diffuse/nodular/rim) and resolution. Of lesions enhancing >35 HU, only 14.3% resolved spontaneously. Delayed enhancement (after negative imaging studies) occurred in two patients; both underwent salvage treatments.
  
  
  CONCLUSIONS
  Most of the time, contrast-enhancements after cryoablation are evident on the first follow-up imaging study. More than 50% of these resolve spontaneously, and only one of four patients need salvage treatment. Delayed appearance of enhancement after previously negative imaging and highly enhancing lesions (>35 HU) are unlikely to resolve and should be considered suspicious for local recurrence or incomplete ablation. Further investigation is warranted to reach a consensus on a radiographic definition of local recurrence after renal cryoablation.
authors: Division of Urology, Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA. matvey.tsivian@duke.edu
authors: Matvey
authors: M
authors: Tsivian
authors: Charles Y
authors: CY
authors: Kim
authors: Jorge R
authors: JR
authors: Caso
authors: Michael D
authors: MD
authors: Rosenberg
authors: Rendon C
authors: RC
authors: Nelson
authors: Thomas J
authors: TJ
authors: Polascik
mesh_terms: D000368:Aged; D003287:Contrast Media; D003452:Cryosurgery / Q000379:methods*; D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000601:surgery*; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care; D014057:Tomography, X-Ray Computed / Q000379:methods*; D017211:Treatment Failure
chemical_list: D003287:Contrast Media