Volumetric 3D assessment of ablation zones after thermal ablation of colorectal liver metastases to improve prediction of local tumor progression
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The goal of this study was to develop and evaluate a volumetric three-dimensional (3D) approach to improve the accuracy of ablation margin assessment following thermal ablation of hepatic tumors.
The 3D margin assessment technique was developed to generate the new 3D assessment metrics: volumes of insufficient coverage (VICs) measuring volume of tissue at risk post-ablation. VICs were computed for the tumor and tumor plus theoretical 5- and 10-mm margins. The diagnostic accuracy of the 3D assessment to predict 2-year local tumor progression (LTP) was compared to that of manual 2D assessment using retrospective analysis of a patient cohort that has previously been reported as a part of an outcome-centered study. Eighty-six consecutive patients with 108 colorectal cancer liver metastases treated with radiofrequency ablation (2002–2012) were used for evaluation. The 2-year LTP discrimination power was assessed using receiver operating characteristic area under the curve (AUC) analysis.
A 3D assessment of margins was successfully completed for 93 out of 108 tumors. The minimum margin size measured using the 3D method had higher discrimination power compared with the 2D method, with an AUC value of 0.893 vs. 0.790 (p = 0.01). The new 5-mm VIC metric had the highest 2-year LTP discrimination power with an AUC value of 0.923 (p = 0.004).
Volumetric semi-automated 3D assessment of the ablation zone in the liver is feasible and can improve accuracy of 2-year LTP prediction following thermal ablation of hepatic tumors.
• More accurate prediction of local tumor progression risk using volumetric 3D ablation zone assessment can help improve the efficacy of image-guided percutaneous thermal ablation of hepatic tumors.
• The accuracy of evaluation of ablation zone margins after thermal ablation of colorectal liver metastases can be improved using a volumetric 3D semi-automated assessment approach and the volume of insufficient coverage assessment metric.
• The new 5-mm volume-of-insufficient-coverage metric, indicating the volume of tumor plus 5-mm margin that remained untreated, had the highest 2-year local tumor progression discrimination power.
KeywordsNeoplasm metastasis Minimally invasive surgical procedures Image processing, computer-assisted
Local tumor progression
Area under the curve
Colorectal cancer liver metastases
Volume of insufficient coverage
We thank James Keller for his help with editing and preparing this manuscript.
Preliminary results were presented as an abstract during the RSNA 2017.
This research project was supported by an internal Department of Radiology seed grant and in part by the NIH/NCI Cancer Center Support Grant P30 CA008748.
Compliance with ethical standards
The scientific guarantor of this publication is Dr. Elena Kaye.
Conflict of interest
The authors of this manuscript declare relationships with the following companies.
C. T. Sofocleous has received research support from BTG, Ethicon (Neuwave); HS Medical, Angiodynamics; Sota Medical; and is a consultant for Ethicon and GE.
S. B. Solomon is a shareholder of Johnson & Johnson, Adgero, Immunomedics, Aspire Bariatrics, and Progenics; has received personal fees from Medtronics, BTG, Astra Zeneca, and Johnson & Johnson; and has a research grant from GE Heathcare.
J. Durack is an investor in and is on scientific advisory board of Adient Medical.
E. Kaye received consulting fees from Galil Medical.
The remaining authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.
Statistics and biometry
Weiji Shi, PhD and Zhigang Zhang, PhD kindly provided statistical advice for this manuscript.
Written informed consent was waived by the Institutional Review Board.
Institutional Review Board approval was obtained.
Study subjects or cohorts overlap
Some study subjects or cohorts have been previously reported in:
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• Diagnostic or prognostic study
• Performed at one institution
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