title: Contrast enhanced ultrasound: Roles in immediate post-procedural and 24-h evaluation of the effectiveness of thermal ablation of liver tumors.
abstract: OBJECTIVE
  To retrospectively assess the diagnostic accuracy of immediate post-procedural CEUS, 24-h CEUS, and 24-h CT in verifying the effectiveness of thermal ablation of liver tumors ablation, using the combined results of 3-month post-procedure CEUS and MDCT as the reference standard.
  
  
  METHODS
  From our database, we selected patients who had immediate post-procedural CEUS and 24-h CEUS and MDCT examinations after undergoing thermal ablation of a liver tumor between January 2009 and March 2010. The study population consisted of 53 subjects and 55 tumors (44 HCC and 11 metastasis) were evaluated. Thirty-seven tumors were treated with radiofrequency and 18 with microwave ablation. Post-procedural CEUS, 24-h CEUS and MDCT, and 3-month follow-up CEUS and MDCT images were blindly reviewed by two radiologists, who measured the size of the ablation area on the post-procedural and 24-h studies. They also evaluated the ability of each of these three index tests to predict the outcome (residual tumor vs. no residual tumor) using imaging studies done at the 3-month follow-up as the reference standard.
  
  
  RESULTS
  Mean tumor diameter on preablation CEUS (the day before treatment) was 20 ± 9 mm. Mean diameter of the necrotic area was 29 ± 9 mm on post-procedural CEUS, 34 ± 11 mm on 24-h CEUS, and 36 ± 11 mm on 24-h MDCT. Diameters of the necrotic area (mean and maximum) on post-procedural CEUS were significantly smaller than those measured on 24-h CEUS or 24-h MDCT, which were not significantly different. For predicting the presence of residual tumor at the 3-month follow-up, post-procedural CEUS, 24-h CEUS, and 24-h MDCT displayed sensitivity of 33%, 33%, and 42%; specificity of 92%, 97%, and 97%; negative predictive value of 84%, 85%, and 83%. The accuracy parameters of these three imaging modalities were not significantly different from one another.
  
  
  CONCLUSIONS
  In patients undergoing thermal ablation for liver tumors, the immediate post-procedural CEUS seems comparable to 24-h CEUS and MDCT in terms of detecting residual disease.
authors.affiliation: Radiodiagnostic Unit, San Gerardo Hospital, Monza, Italy ; Department of Radiodiagnostics, University of Milan-Bicocca, Milan, Italy.
authors.forename: M F
authors.initials: MF
authors.lastname: Meloni
authors.forename: A
authors.initials: A
authors.lastname: Andreano
authors.forename: F
authors.initials: F
authors.lastname: Zimbaro
authors.forename: M
authors.initials: M
authors.lastname: Lava
authors.forename: S
authors.initials: S
authors.lastname: Lazzaroni
authors.forename: S
authors.initials: S
authors.lastname: Sironi
keywords: Ablation techniques; Contrast-enhanced ultrasound; Interventional; Sensitivity and specificity; Ultrasonography