Presentation Authors: Tareq Aro*, Sunghwan Lim, Doru Petrisor, Dan Stoianovici, Baltimore, MD
Introduction: Cystoscopy remains the only acceptable method for demonstrating bladder urothelial carcinoma lesions, various imaging modalities remain unreliable for the diagnosis or follow-up. Intra-vesicle imaging with a saline filled bladder may provide better resolution. No such modality is used to date, even though small and miniature Ultrasound (US) transducers technology exists and is implemented in other medical fields. Using a robot system with mounted US transducer and surface rendering software we try to demonstrate the feasibility of a novel technique for future intra-vesicle surface mapping of the bladder.
Methods: A cylindrical construct with an internal diameter of 10 cm was 3D printed using MakerBot Replicator 2 (MakerBot IndustriesÂ®), a mockup was created using bloom Gel powder, various shapes of gel protrusions representing tumors with sizes 3-50 mm were glued to the interior using molten gel.We used a linear transrectal US transducer (Hitachi EUP-U533) connected to a special robot system developed in Johns Hopkins Urology Robotics Laboratory with software for rendering volume images from 2D US scans. The volume scan of the mockup submerged in water was transferred into 3DSlicerÂ® software, surface mapping was created using segmentation tool. Surface images were examined to determine if all protrusions were identified and if artifacts existed. The software shows both the 3D constructed surface and the original US images so that any area on the surface image can be automatically traced to the US for an operator to decide if it is a rendering artifact or an actual protrusion.
Results: Surface 3D reconstruction was shown for half a cylinder at a time for ease of interpretation, a full 360Â° volume image is available when needed.After examining the final rendered reconstruct (Figure), all the protrusions where clearly visible on the surface images, small artifact areas were dismissed as non-tumors when looking at the original US images in the software as explained.
Conclusions: Intra-vesical scanning of a water filled bladder with a special robotic system and surface mapping software may be able to replace cystoscopy in the future. The miniature US technology already exists and needs adaptation for urologic use. Future trials with new specialized US probes are necessary.