Detectability of Target Lesion During CT-Guided Tumor Ablations: Impact on Ablation Outcome

Purpose Small hepatic malignancies scheduled for CT-guided percutaneous ablation may have been identified in the hepatobiliary phase of liver MRI or in a specific phase of multi-phase CT but may be occult on unenhanced CT used to guide the ablation. We investigated whether the detectability of the target lesion would impact the efficacy of CT-guided hepatic tumor ablations. Materials and Methods We included 69 patients with 99 malignant liver lesions (25 primary, 44 metastases) who underwent IRE (n = 35), RFA (n = 41), or MWA (n = 23) between 01/2015 and 06/2018. All procedures were performed under CT guidance. Lesions not detectable on CT (NDL) were targeted through identification of anatomical landmarks on preinterventional contrast-enhanced CT or MRI. Rates of incomplete ablation, size of ablation zone, local tumor recurrence, intrahepatic progression-free survival (ihPFS), and adverse event rates were compared for detectable lesions (DL) vs. NDL. Results 40 lesions were NDL, and 59 lesions were DL on unenhanced CT. The mean follow-up was 16.2 months (14.8 for DL and 18.2 for NDL). The mean diameter of NDL and DL was similar (12.9 mm vs. 14.9 mm). The mean ablation zone size was similar (37.1 mm vs. 38.8 mm). Incomplete ablation did not differ between NDL vs. DL (5.0 % [2/40; 0.6–16.9 %] vs. 3.4 % [2/59; 0.4–11.7 %]), nor did local tumor recurrence (15.4 % [6/39; 5.7 %–30.5 %] vs. 16.9 % [10/59; 8.4–29.0 %]), or median ihPFS (15.5 months vs. 14.3 months). Conclusion Target lesion detectability on interventional CT does not have a significant impact on outcome after percutaneous liver ablation when anatomical landmarks are used to guide needle placement. Key Points: Citation Format