Some cancer patients display a less aggressive form of metastatic disease, characterized by a low tumor burden and involving a smaller number of sites, which is referred to as “oligometastatic disease” (OMD). This review discusses new biomarkers, as well as methodological challenges and perspectives characterizing OMD. Recent studies have revealed that specific microRNA profiles, chromosome patterns, driver gene mutations (ERBB2, PBRM1, SETD2, KRAS, PIK3CA, SMAD4), polymorphisms (TCF7L2), and levels of immune cell infiltration into metastases, depending on the tumor type, are associated with an oligometastatic behavior. This suggests that OMD could be a distinct disease with specific biological and molecular characteristics. Therefore, the heterogeneity of initial tumor burden and inclusion of OMD patients in clinical trials pose a crucial methodological question that requires responses in the near future. Additionally, a solid understanding of the molecular and biological features of OMD will be necessary to support and complete the clinical staging systems, enabling a better distinction of metastatic behavior and tailored treatments.

Purpose: To assess efficacy and safety of cone beam computed tomography (CBCT) in the radiofrequency ablation (RFA) of osteoid osteoma (OO) in children and adolescents, and to compare technical success, clinical success, radiation dose and procedure duration time of CBCT guidance to conventional computed tomography (CT) guidance. Materials and methods: Between 2015 and 2019, 53 consecutive percutaneous RFA were performed on pediatric patients with CBCT or conventional CT guidance, respectively, in 24 and 29 children and adolescents with 24-month follow-up. Dose area product (DAP) and dose length product (DLP) were recorded, respectively, for CBCT and conventional CT and converted to effective doses (ED). Results: CBCT and conventional CT groups were similar in terms of patient age and weight, tumor size and tumor location. Technical success was achieved in all cases. Primary clinical success was 91.67% (22/24) for the CBCT group and 89.66% (26/29) for the conventional CT group. Mean DAP was 64.75Gycm2 (range 6.0–266.7). Mean DLP was 972.62mGycm (range 337–2344). ED was significantly lower in the CBCT group compared to the conventional CT group (0.34 mSv vs. 5.53 mSv, p = 0.0119). Procedure duration time was not significantly longer in the CBCT group (102.25 min vs. 92.34 min, p = 0.065). No major complication was registered. Minor complications were observed in 4 patients (2 in CBCT; 2 in conventional CT). Conclusions: Compared to conventional CT guidance, CBCT guidance for percutaneous OO ablation shows similar technical and clinical success rates, with reduced radiation dose and equivalent procedure duration time. This technique helps sparing dose exposure to pediatric patients.

4027 Background: The prognosis in HCC was evaluated in a large series of patients receiving radioembolization (RE). Methods: 250patients with unresectable HCC were recruited consecutively from 8 European centers and received RE using 90Y-labeled resin microspheres (SIR-Spheres). Prognostic factors significant on univariate analysis were combined in multivariate models to identify the predictors of survival. Results: Patients (mean age 65.2 years) received a median activity of 1.7 GBq. Most patients were Child-Pugh class A (81%), with multinodular disease (74%) and 16% had portal vein occlusion. Common early adverse events (primarily grade 1/2) were early (days 1-7) abdominal pain (24%) and fatigue (30%). Hyperbilirubinemia was an intermediate (8 days to 3 mo) or late (3-6 mo) event in 33% and 28% of patients, a minority experiencing grade 3 events (3.6% and 5.7%), respectively. Median survival was 14.1 mo (95% CI 12.7-17.9). Survival varied significantly by CLIP: CLIP 0: 24.4 mo (19.6-not reached), CLIP 1...

Interventional radiology offers minimally invasive procedures guided by real-time imaging, reducing surgical risks and enhancing patient recovery. While beneficial to patients, these advancements increase occupational hazards for physicians due to chronic exposure to ionizing radiation. This exposure raises health risks like radiation-induced cataracts, cardiovascular disease, and cancer. Despite regulations like the European Council Directive 2013/59/EURATOM, which sets limits on whole-body and eye lens doses, no dose limits exist for the brain and meninges, since the brain has traditionally been considered a radioresistant organ. Recent studies, however, have highlighted radiation-induced brain damage, suggesting that meningeal exposure in interventional radiology may be underestimated. This study evaluates the entrance air Cumulative mean annual entrance air kerma to the skullull during interventional radiology procedures, using thermoluminescent dosimeters and controlled exposure simulations. Data were collected by varying the exposure time and analyzing the contribution to the entrance air kerma on each side of the head. The results indicate that, considering the attenuation of the cranial bone, the absorbed dose to the brain, obtained by averaging the head entrance air kerma for the right, front, and left sides of the operator’s head, could represent 0.81% to 2.18% of the annual regulatory limit in Italy of 20 mSv for the average annual effective dose of exposed workers (LD 101/2020). These results provide an assessment of brain exposure, highlighting the relatively low but non-negligible contribution of brain irradiation to the overall occupational dose constraint. Additionally, a correlation between entrance air kerma and the Kerma-Area Product was observed, providing a potential method for improved dose estimation and enhanced radiation safety for interventional radiologists.