The Added Diagnostic Value of Transcatheter CT Hepatic Arteriography for Intraprocedural Detection of Previously Unknown Colorectal Liver Metastases During Percutaneous Ablation and Impact on the Definitive Treatment Plan

PURPOSE: This study assessed the diagnostic value of CT hepatic arteriography (CTHA) for the intraprocedural detection of previously unknown colorectal liver metastases (CRLM) and the impact on the definitive treatment plan. MATERIALS AND METHODS: All patients treated with CTHA-guided percutaneous ablation for CRLM between January 2012 and March 2022 were identified from the Amsterdam Colorectal Liver Met Registry (AmCORE). Radiology reports of the ablative procedure and follow-up imaging were reviewed to see if (a) previously unknown CRLM were detected intra-procedurally and if (b) new CRLM, potentially missed on CTHA, appeared within 6 months following the procedure; three abdominal radiologists re-reviewed the baseline CTHA scans of these patients with early recurrence. To ratify immediate ablations of concomitantly detected CRLM, the upper limit of false positives was predefined at 10%. RESULTS: One hundred and fifty-two patients were included. With CTHA, a total of 17 additional tumours in 15 patients were diagnosed and treated immediately, two representing disappeared tumours following systemic chemotherapy. Compared to the conventional contrast-enhanced (ce)CT, ceMRI and 18F-FDG PET-CT, adding CTHA was superior for the detection of CRLM (P < .001). Within 12 months of follow-up 121, new CRLM appeared in 49/152 patients (32.2%); retrospective blinded assessment revealed 56 to already be visible on the baseline CTHA scan (46%); four lesions without substrate on follow-up scans were considered false positives (n = 4/60; 7%). Arterial ring enhancement was the most frequently reported imaging characteristic (n = 45/60; 75%). CONCLUSION: The subsequent use of CTHA has added value for the detection of previously unknown and vanished CRLM. Taking into account the low number of false positives (7%) and the favourable safety profile of percutaneous ablation, we believe that immediate ablation of typical ring-enhancing supplementary tumours is justified and sufficiently validated. LEVEL OF EVIDENCE: Level 3; individual cross-sectional study with consistently applied reference standard and blinding.