THE USE OF THE CONE-BEAM COMPUTED TOMOGRAPHY FUSION IMAGING AND OF DEDICATED SOFTWARE FOR ABLATION VOLUME PREDICTION IN PERCUTANEOUS MICROWAVE ABLATION OF LIVER PRIMARY TUMORS

Purpose To evaluate the clinical impact of a protocol for image-guided percutaneous thermal ablation of primary liver tumors that involves the use of cone-beam computed tomography (CBCT), fusion imaging and of a software for ablation volume prediction. Materials and Methods This study included 80 consecutive patients with 101 hepatocellular carcinomas (HCCs) treated with image-guided percutaneous microwave ablation (MWA) between 01/202106/ 2022 in a single institution: Fondazione IRCCS Cà Granda – Ospedale Maggiore Policlinico, Milan, Italy. Patients were divided in 2 groups: Group A, treated following a specific protocol which involved the use of CBCT, fusion imaging and of a software for ablation volume prediction (41 HCCs in 37 patients), and Group B, treated with standard ultrasound (US) guidance (60 HCCs in 43 patients). Data regarding patients, tumors and procedures were registered. Images from follow-up CT/MR exams performed at 1, 3 and 6 months were reviewed to assess outcomes as residual disease, local tumor progression, intrahepatic distant recurrence, local and overall disease survival rates. Follow-up at 1, 3 and 6 months in group A and B was available in 100%, 57%, 38% and in 100%, 49% and 35% of cases respectively. Ablation response at 1 month was evaluated according to the Modified Response Evaluation Criteria In Solid Tumours (mRECIST) for HCC. A comparison of baseline variables and outcome rates between groups A and B was performed. For outcomes at 1 month, propensity score weighting was then performed performed to control for confounders in age, tumor location, size, and recurrence Results Among all baseline variables, group A and B only differed regarding age, new-vs-residual target tumor rates (higher in group A) and number of subcapsular or perivascular tumors (higher in group B). Among group A patients the protocol led to repositioning the MWA antenna in 49% of cases. There was a significant difference in local tumor response at 1 month between the groups in the form of residual disease rates and according to mRECIST. Cumulative local tumor progression rates at 3 and 6 months or in the intrahepatic distant recurrence rates at 1, 3 and 6 months showed no statistically significant differences, probably due to the limited number of cases. Local and overall disease-free survival similarly showed statistically significant differences at 1 month only. Among all variables, logistic regression after propensity score weighting demonstrated a unique protective effect of belonging to group A against the presence of residual disease at 1 month. Conclusions The use of a protocol that includes CBCT fusion imaging and ablation volume prediction software during US-guided percutaneous thermal ablation of liver HCCs provided a better tumor local control 1 month after procedure, lowering residual disease. Further studies with larger population and longer follow-up time are needed to confirm outcome data at 1 month, better define later outcomes, and eventually identify the subgroups of patients who could benefit more from the protocol application.