Is there a need for MRI within 24 hours after CT-guided percutaneous thermoablation of the liver?

Acta Radiol. 2015 Jan;56(1):10-7. doi: 10.1177/0284185114520858. Epub 2014 Jan 20.

Abstract

Background: Radiofrequency (RFA) and microwave ablation (MWA) are established minimally invasive techniques for treatment of hepatic tumors.

Purpose: To compare technical success and accuracy of hepatic thermoablation using computed tomography (CT) and magnetic resonance imaging (MRI) acquired 24 h after ablation with regard to evaluation of the post-interventional ablation zone and local tumor recurrence (LTR), and to assess whether additional MRI within 24 h is beneficial.

Material and methods: Thirty-two patients (23 men, 9 women; mean age, 60 years) with 48 lesions were included in this retrospective study. CT was performed immediately and MRI was performed 24 h after ablation. Diameter and volume calculations of the ablation zone were compared (T-Test). Technical success and ablation margin distinction, shape, and configuration were evaluated (κ-statistic). Local effectiveness was calculated based on follow-up imaging. Technical success and ablation margin features were correlated with LTR (log-rank test, Fisher's exact test).

Results: Ablation zone volumes were significantly higher with MRI compared to CT (P < 0.05; mean volume, 55.19 and 45.97 mL). Agreement between CT and MRI for technical success was good (κ = 0.801) and for margin conspicuity fair (κ = 0.289). LTR was 26.1% (mean follow-up, 11.7 months). LTR showed no correlation with technical success or margin conspicuity.

Conclusion: CT and MRI are suited for early evaluation of technical success after thermoablation. Within 24 h a significant increase of the ablation volume is observed, which has to be taken into account when interpreting immediate postprocedural imaging and treating lesions near critical structures. Additional MRI 24 h after ablation seems of limited value regarding prognosis of LTR, especially with regards to evaluation of ablation margin shape and conspicuity.

Keywords: Radiofrequency ablation (RFA); microwave ablation (MWA); tumor recurrence.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Electrocoagulation / methods*
  • Female
  • Hepatectomy / methods
  • Humans
  • Hyperthermia, Induced / methods*
  • Liver Neoplasms / diagnosis*
  • Liver Neoplasms / surgery*
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Needs Assessment
  • Neoplasm, Residual
  • Prognosis
  • Reproducibility of Results
  • Retrospective Studies
  • Sensitivity and Specificity
  • Surgery, Computer-Assisted
  • Tomography, X-Ray Computed / methods*
  • Treatment Outcome