Enhancing Catheter-Assisted C-Arm CT-Guided Ablation with PET/CT Fusion: A Pictorial Overview of Multimodal Synergy...

Background/Objectives: Image-guided percutaneous thermal ablation is an established local treatment for selected patients with liver metastases, provided that accurate tumor targeting and adequate ablation margins can be achieved. However, lesion detection, target delineation, and intraprocedural margin verification remain challenging in post-chemotherapy or previously treated lesions that may become morphologically inconspicuous or radiologically occult. Catheter-assisted C-arm (cone-beam) CT hepatic arteriography (CBCT-HA) improves intraprocedural visualization of tumor vascularity and supports streamlined workflows within the angiography suite, yet it may underestimate tumor extent in lesions with limited or absent angiographic conspicuity. This pictorial essay illustrates the feasibility and added value of integrating preprocedural PET/CT with intraprocedural CBCT-HA for liver tumor ablation. Methods: Representative clinical cases of percutaneous liver tumor ablation guided by PET-CBCT-HA fusion are presented. Preprocedural PET/CT datasets were rigidly registered and fused with intraprocedural CBCT-HA to support tumor detection, target delineation, ablation planning, and real-time intraprocedural margin assessment. The complementary roles of metabolic and angiographic imaging were evaluated qualitatively across different clinical scenarios. Results: PET-CBCT-HA fusion improved detection and delineation of viable tumor components that were occult or insufficiently defined on CBCT-HA alone, particularly in post-chemotherapy or previously treated lesions. Conversely, CBCT-HA identified angiographically evident lesions not apparent on PET/CT. The combined approach enabled confident target definition, biologically informed ablation planning, and immediate post-ablation verification of metabolic and angiographic coverage, supporting margin-oriented intraprocedural decision-making. Conclusions: By integrating complementary metabolic and vascular information into a single-session workflow, PET-CBCT-HA fusion represents a multimodal guidance strategy that enhances lesion visualization and intraprocedural margin assessment. This approach may improve local tumor control in complex post-treatment and oligometastatic liver disease.