3D margin assessment predicts local tumor progression after ablation of colorectal cancer liver metastases

Abstract

Objective

To determine the feasibility and prognostic value of 3D measuring of the ablation margins using a dedicated image registration software.

Methods

This retrospective study included 104 colorectal liver metastases in 68 consecutive patients that underwent microwave ablation between 08/2012 and 08/2019. The minimal ablation margin (MM) was measured in 2D using anatomic landmarks on contrast enhanced CT(CECT) 4–8 weeks post-ablation, and in 3D using an image registration software and immediate post-ablation CECT. Local tumor progression (LTP) was assessed by imaging up to 24 months after ablation. A blinded interventional radiologist provided feedback on the possibility of additional ablation after examining the 3D-margin measurements.

Results

The 3D-margin assessment was completed in 79/104 (76%) tumors without the need for target manipulation. In 25/104 (24%) tumors, manipulation was required due to image misregistration. LTP was observed in 40/104 (38.5%) tumors: 92.5% vs 7.5% for those with margin <5mm vs ≥5mm, respectively (p = 0.0001). The 2D and 3D-assessments identified margin <5mm in 17/104 (16%), and in 74/104 (71%) ablated tumors, respectively (p < 0.01). The sensitivity and specificity of the 3D software for predicting LTP was 93% (37/40) and 42% (27/64), respectively. Additional ablation to achieve a MM of 5 mm would have been offered in 26/37 cases if the 3D-margin assessment was available intraoperatively.

Conclusion

Image registration software can measure ablation margins and detect MM under 5 mm intraoperatively, with significantly higher sensitivity than the 2D technique using landmarks on the post-ablation CECT. The identification of a margin under 5 mm is strongly associated with LTP.

Keywords:

• Thermal ablation
• ablation margin assessment
• colorectal cancer liver metastases

Disclosure statement

Etay Ziv: reports grants from RSNA, grants from SIR, grants from NANETS, grants from AACR, grants from MSKCC, grants from Ethicon, grants from Druckenmiller, grants from Novartis, outside the submitted work. Stephen B. Solomon: Dr. Solomon reports grants from Johnson & Johnson, grants from Varian, personal fees from XACT Robotics, grants from GE Healthcare, grants from Elesta, outside the submitted work. Constantinos T. Sofocleous: Dr. Sofocleous reports grants from NCI/NIH, during the conduct of the study; grants from Ethicon J&J, grants from SIRTEX Medical Inc, grants from BSX/BTG, outside the submitted work; and Consultant, Advisory Boards for: J&J/Ethicon, Terumo, BTG/Boston Scientific, SIRTEX, Varian. Rest of the authors declare they have no conflict of interest.

Data availability statement

The data that support the findings of this study are available from the authors on reasonable request.

Additional information

Funding

Funded through a grant supported by Ethicon Johnson & Johnson Memorial Sloan Kettering Cancer Center is supported by the grant P30 CA008748 from the National Cancer Institute (NCI).