Radiopharmaceutical Oncology Care Supported by Ultrasound-Guided Superior Vena Cava-Right Atrial Junction Port Tip Positioning in Adult Cancer Patients.

Background: In this single-center retrospective study, the authors evaluated whether real-time ultrasound-guided positioning of an implantable venous access port catheter tip at the superior vena cava-right atrial junction (SVC-RAJ) reduces the risk of catheter-related thrombosis (CRT) in adult patients with cancer and developed a multivariable risk prediction model to support individualized prevention.Methods: Clinical data from 600 consecutive patients who underwent port implantation at Zhongshan People's Hospital were analyzed. Patients were grouped according to final catheter tip position (SVC-RAJ versus non-SVC-RAJ), and CRT incidence was compared between groups.Results: The overall incidence of CRT was 30.33% (182/600) and was significantly lower in the SVC-RAJ group than in the non-SVC-RAJ group (22.42% vs. 38.73%, p < 0.001). In multivariable analysis, catheter tip positioning at the SVC-RAJ remained an independent protective factor (odds ratio = 0.517, 95% confidence interval [CI]: 0.353-0.756). Age, body mass index (BMI), tumor stage, neutrophil-to-lymphocyte ratio, D-dimer level, catheterization duration, and prophylactic anticoagulation status were also independently associated with CRT. A nomogram integrating these variables demonstrated good discrimination (area under the curve = 0.866, 95% CI: 0.837-0.895), with a sensitivity of 70.33% and a specificity of 85.89%. Performance across specific age or BMI strata was not separately evaluated in this study, and further stratified validation in larger datasets is needed to assess model consistency across demographic subgroups.Conclusions: These findings support ultrasound-guided SVC-RAJ positioning as a clinically relevant strategy for reducing CRT risk and maintaining reliable venous access in contemporary oncology care pathways.