title: CT-Guided Microwave Ablation of 45 Renal Tumors: Analysis of Procedure Complexity Utilizing a Percutaneous Renal Ablation Complexity Scoring System.
abstract: OBJECTIVE
  To develop a scoring system that stratifies complexity of percutaneous ablation of renal tumors.
  
  
  METHODS
  Analysis was performed of 36 consecutive patients (mean age, 64 y; range, 30-89 y) who underwent CT-guided microwave (MW) ablation of 45 renal tumors (mean tumor diameter, 2.4 cm; range, 1.2-4.0 cm). Technical success and effectiveness were determined based on intraprocedural and follow-up imaging studies. The RENAL score and the proposed percutaneous renal ablation complexity (P-RAC) score were calculated for each tumor.
  
  
  RESULTS
  Technical success was 93.3% (n = 42). Biopsy of 38 of 45 renal tumors revealed 23 renal cell carcinomas. Median follow-up period was 9.7 months (range, 2.9-46.8 months). There were no tumor recurrences. One major complication, ureteropelvic junction stricture, occurred (2.6%). The P-RAC score was found to differ statistically from the RENAL score (t = 3.754, df = 44, P = .001). A positive correlation was found between the P-RAC score and number of antenna insertions (r = .378, n = 45, P = .011) and procedure duration (r = .328, n = 45, P = .028). No correlation was found between the RENAL score and number of MW antenna insertions (r = .110, n = 45, P = .472) or procedure duration (r = .263, n = 45, P = .081). Hydrodissection was significantly more common in the P-RAC high-complexity category than in low-complexity category (χ2= 12.073, df = 2, P = .002).
  
  
  CONCLUSIONS
  The P-RAC score may be useful in stratifying percutaneous renal ablation complexity. Further studies with larger sample sizes are necessary to validate the P-RAC score and to determine if it can predict risk of complications.
authors.affiliation: Radiology Specialists of Florida, Florida Hospital, 601 East Rollins Street, Orlando, FL 32803. Electronic address: alberto.mansilla.md@flhosp.org.
authors.forename: Alberto V
authors.initials: AV
authors.lastname: Mansilla
authors.affiliation: Volunteer Research Program, Florida Hospital, 601 East Rollins Street, Orlando, FL 32803.
authors.forename: Eugene E
authors.initials: EE
authors.lastname: Bivins
authors.affiliation: Radiology Specialists of Florida, Florida Hospital, 601 East Rollins Street, Orlando, FL 32803.
authors.forename: Francisco
authors.initials: F
authors.lastname: Contreras
authors.affiliation: Radiology Specialists of Florida, Florida Hospital, 601 East Rollins Street, Orlando, FL 32803.
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Hernandez
authors.affiliation: Department of Radiology, Florida Hospital, 601 East Rollins Street, Orlando, FL 32803.
authors.forename: Nathan
authors.initials: N
authors.lastname: Kohler
authors.affiliation: Office of Research Administration, Florida Hospital, 601 East Rollins Street, Orlando, FL 32803.
authors.forename: Julie W
authors.initials: JW
authors.lastname: Pepe
mesh_terms: D055011:Ablation Techniques / Q000009:adverse effects; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008297:Male; D008872:Microwaves / Q000009:adverse effects / Q000627:therapeutic use*; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology; D011237:Predictive Value of Tests; D015641:Radiography, Interventional / Q000379:methods*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome