Intratumoural Contrast Tagging During CT-Hepatic Arteriography-Guided Microwave Ablation of Colorectal Liver Metastases (t-CTHA) to Enhance Tumour Targeting and Margin Assessment.

purposeTo evaluate a technique using intratumoural contrast tagging (t-CTHA), to enhance targeting accuracy and confirm ablation margins during CTHA-guided percutaneous microwave ablation (MWA) of colorectal liver metastases (CRLM).

methodsThis prospective AmCORE-based study (August 2022-May 2025) included participants who underwent CTHA-guided MWA procedures for CRLM. Prior to energy delivery, contrast medium was injected into the common hepatic artery, with CT-imaging start delays (7 and 22 s) adjusted based for optimal tumour conspicuity, to allow the contrast to accumulate within the tumour. Successful tagging was defined by either complete and homogeneous opacification of the tumour or partial contrast capture aiding alignment during image co-registration. Other outcome measures included adverse events (CTCAE v5.0), local tumour progression-free survival (LTPFS), local control (LC), overall survival (OS), and distant progression-free survival (DPFS).

resultsA total of 35 patients underwent 39 t-CTHA-guided MWA procedures for 68 CRLM. Complete tagging was achieved in 79.4% of tumours, partial tagging in 19.1% and inadequate tagging in one tumour (1.5%). The evaluation of post-ablation triple-phase CTHA images, the analysis of co-registered pre- and post-ablation images, and their combined use accurately correlated with complete ablations in all cases. Adverse events were reported in 15.4% of procedures, with two (5.1%) classified as major. None were associated to the catheter or tagging technique. No LTP was reported over a follow-up period of 6 months (range: 2.2-32.4).

conclusionT-CTHA optimizes real-time tumour conspicuity, improves margin assessment by minimizing shrinkage and misregistration issues, and potentially reduces the risk of LTP. LEVEL OF EVIDENCE III: Local non-random sample.