Hug sign in intraprocedural cone-beam-CT to predict short-term response to combined treatment of hepatocellular carcinoma

ObjectivesCombined treatment of ablation and chemoembolization for hepatocellular carcinoma represents a promising therapy to increase treatment efficacy and improve patient survival. The "hug sign" is a recently introduced radiological sign consisting in deposition of beads/contrast agent during transarterial chemoembolization in the hyperemic area surrounding the post-ablation volume, seen during intraprocedural unenhanced cone-beam CT, that may indicate intraprocedural success. Aim of our retrospective study was to analyze the usefulness of the "hug sign" at the intraprocedural unenhanced cone-beam CT as an early predictor of response to combined treatment, based on the hug sign angle.Materials and methodsBetween January 2017 and September 2021 all patients with hepatocellular carcinoma which underwent a combined treatment of thermal ablation followed by chemoembolization were enrolled. All treated patients underwent immediate post-procedural unenhanced cone-beam CT to evaluate the deposition of contrast agent, lipiodol or radiopaque beads and to assess the percentage of coverage of the ablated area with the contrast agent (hug sign angle). Patients with missing pre-procedural, intra-procedural and/or post-procedural data/imaging, or with poor-quality post-procedural cone-beam CT images were excluded.Results128 patients (mean age, 69.3 years +/- 1.1 [standard deviation]; 87 men) were evaluated. Our study evidenced that 84.4% (81/85) of patients with a hug sign angle of 360 degrees had no residual tumor at the first 1-/3-months follow-up examination. A hug sign angle of 360 degrees also showed to be an independent protective factor against residual tumor at multivariate analysis.ConclusionUnenhanced cone-beam CT performed at the end of a combined treatment with ablation plus chemoembolization can effectively predict an early treatment response on radiological images, when a hug sign angle of 360 degrees was detected.