Room: Track 4
Purpose: To improve volumetric visualization, therapy applicator targeting, and verification of applicator placements by developing a 3D ultrasound (US) mechanical guidance system for cost-effective image guidance during focal liver tumor ablation therapy, potentially reducing post-therapy local cancer recurrence and increasing the clinical feasibility of traditionally complex multi-applicator approaches.
Methods: A three-motor mechanical scanner for variable 3DUS field-of-views (FOV) was mounted on a portable counterbalanced mechanical “arm” with five encoders to move and track the position of a 2DUS transducer. Volunteer imaging was performed for assessing clinical feasibility and a phantom was used to perform mock interventional procedures by selecting a target in a 3DUS image, navigating to the target, and performing needle insertion using a custom 3D-printed guide. Two 3DUS image geometries were investigated to assess the accuracy of a small-footprint approach and a large FOV approach when using either an automatic transducer positioning or encoder tracked freehand navigation approach. A total of 32 insertions were evaluated and validated with registered cone-beam CT images.
Results: Clinically relevant structures were clearly visualized in the volunteer images (kidney, hepatic vein, and portal vein). Mean needle tip targeting error based on 3DUS and CT were 4.4±3.1 mm and 4.0±2.8 mm, respectively, when using an automatic navigation approach and 7.1±2.9 mm and 7.8±2.4 mm using a tracked freehand approach.
Conclusion: The proposed mechanically assisted 3DUS guidance system was able to image a volunteer with promising clinical utility and has the potential to guide needles accurately to 3DUS-derived targets using a motorized navigation approach. Current work is focused on performing imaging of patients undergoing focal liver tumor ablation therapy to assess needle applicator placement accuracy.
Funding Support, Disclosures, and Conflict of Interest: Ontario Institute of Cancer Research, the Canadian Institutes of Health Research, and the Natural Sciences and Engineering Research Council of Canada