title: Percutaneous Renal Cryoablation: Short-Axis Ice-Ball Margin as a Predictor of Outcome.
abstract: OBJECTIVE
  To determine if CT characteristics of intraprocedural ice balls correlate with outcomes after cryoablation.
  
  
  METHODS
  A retrospective review was performed on 63 consecutive patients treated with renal cryoablation. Preprocedural and intraprocedural images were used to identify the size and location of renal tumors and ice balls as well as the tumor coverage and ice-ball margins. Review of follow-up imaging (1 mo and then 3-6-mo intervals) distinguished successful ablations from cases of residual tumor.
  
  
  RESULTS
  Patients who underwent successful ablation (n = 50; 79%) had a mean tumor diameter of 2.5 cm (range, 0.9-4.3 cm) and mean ice-ball margin of 0.4 cm (range, 0.2-1.2 cm). Patients with residual tumor (n = 13; 21%) had a mean tumor diameter of 3.8 cm (range, 1.8-4.5 cm) and mean ice-ball margin of -0.4 cm (range, -0.9 to 0.4 cm). Residual and undertreated tumors were larger and had smaller ice-ball margins than successfully treated tumors (P < .01). Ice-ball diameters were significantly smaller after image reformatting (P < .01). Ice-ball margins of 0.15 cm had 90% sensitivity, 92% specificity, and 98% positive predictive value for successful ablation. Success was independent of tumor location or number of cryoprobes.
  
  
  CONCLUSIONS
  Ice-ball margin and real-time intraprocedural reformatting could be helpful in predicting renal cryoablation outcomes. Although a 0.5-cm margin is preferred, a well-centered ice ball with a short-axis margin greater than 0.15 cm strongly correlated with successful ablation.
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104.
authors.forename: Benjamin H
authors.initials: BH
authors.lastname: Ge
authors.affiliation: Department of Urology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Guzzo
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Nadolski
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Soulen
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104.
authors.forename: Timothy W I
authors.initials: TW
authors.lastname: Clark
authors.affiliation: Department of Urology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104.
authors.forename: Stanley B
authors.initials: SB
authors.lastname: Malkowicz
authors.affiliation: Department of Urology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Wein
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Hunt
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce St., 1 Silverstein, Philadelphia, PA 19104. Electronic address: stav@uphs.upenn.edu.
authors.forename: S William
authors.initials: SW
authors.lastname: Stavropoulos
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003452:Cryosurgery / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D047368:Tumor Burden