Korean J Radiol.  2018 Dec;19(6):1053-1065. 10.3348/kjr.2018.19.6.1053.

Prediction of Local Tumor Progression after Radiofrequency Ablation (RFA) of Hepatocellular Carcinoma by Assessment of Ablative Margin Using Pre-RFA MRI and Post-RFA CT Registration

  • 1Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea. jmsh@snu.ac.kr
  • 2Department of Radiology, Seoul National University College of Medicine, Seoul 03080, Korea.
  • 3Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 03087, Korea.
  • 4Siemens Healthcare, Forchheim 91301, Germany.
  • 5Department of Radiology, SMG-SNU Boramae Medical Center, Seoul 07061, Korea.
  • 6Department of Radiology, KonKuk University Medical Center, Seoul 05030, Korea.
  • 7Department of Radiology, Chung-Ang University Hospital, Seoul 06973, Korea.


To evaluate the clinical impact of using registration software for ablative margin assessment on pre-radiofrequency ablation (RFA) magnetic resonance imaging (MRI) and post-RFA computed tomography (CT) compared with the conventional side-by-side MR-CT visual comparison.
In this Institutional Review Board-approved prospective study, 68 patients with 88 hepatocellulcar carcinomas (HCCs) who had undergone pre-RFA MRI were enrolled. Informed consent was obtained from all patients. Pre-RFA MRI and post-RFA CT images were analyzed to evaluate the presence of a sufficient safety margin (≥ 3 mm) in two separate sessions using either side-by-side visual comparison or non-rigid registration software. Patients with an insufficient ablative margin on either one or both methods underwent additional treatment depending on the technical feasibility and patient's condition. Then, ablative margins were re-assessed using both methods. Local tumor progression (LTP) rates were compared between the sufficient and insufficient margin groups in each method.
The two methods showed 14.8% (13/88) discordance in estimating sufficient ablative margins. On registration software-assisted inspection, patients with insufficient ablative margins showed a significantly higher 5-year LTP rate than those with sufficient ablative margins (66.7% vs. 27.0%, p = 0.004). However, classification by visual inspection alone did not reveal a significant difference in 5-year LTP between the two groups (28.6% vs. 30.5%, p = 0.79).
Registration software provided better ablative margin assessment than did visual inspection in patients with HCCs who had undergone pre-RFA MRI and post-RFA CT for prediction of LTP after RFA and may provide more precise risk stratification of those who are treated with RFA.


Radiofrequency ablation; Fusion; Margin; Local tumor progression; Magnetic resonance imaging
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