Real-Time US-18FDG-PET/CT Image Fusion for Guidance of Thermal Ablation of 18FDG-PET-Positive Liver Metastases: The Added Value of Contrast Enhancement

PurposeTo assess the feasibility of US-(18)FDG-PET/CT fusion-guided microwave ablation of liver metastases either poorly visible or totally undetectable with US, CEUS and CT, but visualized by PET imaging.Materials and MethodsTwenty-three patients with 58 liver metastases underwent microwave ablation guided by image fusion system that combines US with (18)FDG-PET/CT images. In 28/58 tumors, (18)FDG-PET/CT with contrast medium (PET/CECT) was used. The registration technical feasibility, registration time, rates of correct targeting, technical success at 24h, final result at 1year and complications were analyzed and compared between the PET/CT and PET/CECT groups.ResultsRegistration was successfully performed in all cases with a mean time of 7.8+1.7min (mean+standard deviation), (4.6+1.5min for PET/CECT group versus 10.9+1.8min for PET/CT group, P<0.01). In total, 46/58 (79.3%) tumors were correctly targeted, while 3/28 (10.7%) and 9/30 (30%) were incorrectly targeted in PET/CT and PET/CECT group, respectively (P<0.05). Complete ablation was obtained at 24h in 70.0% of cases (n=40 tumors), 23/28 (82.1%) in the PET/CECT group and 17/30 (56.7%) in the PET/CT group (P<0.037). Fourteen tumors underwent local retreatment (11 ablations, 2 with resection and 1 with stereotactic body radiation therapy), while 4 tumors could not be retreated because of distant disease progression and underwent systemic therapy. Finally, 54/58 (93.1%) tumors were completely treated at 1year. One major complication occurred, a gastrointestinal hemorrhage which required surgical repair.ConclusionsPercutaneous ablation of (18)FDG-PET-positive liver metastases using fusion imaging of real-time US and pre-acquired (18)FDG-PET/CT images is feasible, safe and effective. Contrast-enhanced PET/CT improves overall ablation accuracy and shortens procedural duration time.