Early Clinical Feasibility Evaluation of an Augmented Reality Platform for Guidance and Navigation during Percutaneous Tumor Ablation.

An augmented reality platform with a head-mounted display and electromagnetic tracking of instruments was developed for percutaneous procedural guidance. Earlier work had demonstrated bench and first-in-human feasibility of the platform. This report further evaluated the clinical usability and benefits of this technology. The platform was used in 12 patients who had been referred for percutaneous thermal ablation of abdominal soft tissue tumors. In 10 cases, the intraprocedural holographic guidance agreed with the standard imaging guidance. The evaluation was limited in 2 cases because of anatomic and workflow issues. Overall, this series demonstrated the clinical feasibility of this platform and the potential benefits of its use in percutaneous procedures.

Three-Dimensional Holographic Guidance, Navigation, and Control (3D-GNC) for Endograft Positioning in Porcine Aorta: Feasibility Comparison With 2-Dimensional X-Ray Fluoroscopy.

OBJECTIVES: Intraprocedural deployment of endovascular devices during complex aortic repair with 2-dimensional (2D) x-ray fluoroscopic guidance poses challenges in terms of accurate delivery system positioning and increased risk of x-ray radiation exposure with prolonged fluoroscopy times, particularly in unfavorable anatomy. The objective of this study was to assess feasibility of using an augmented reality (AR) system to position and orient a modified aortic endograft delivery system in comparison with standard fluoroscopy. MATERIALS AND METHODS: The 3-dimensional guidance, navigation, and control (3D-GNC) prototype system was developed for eventual integration with the Intra-Operative Positioning System (IOPS, Centerline Biomedical, Cleveland, OH) to project spatially registered 3D holographic representations of the subject-specific aorta for intraoperative guidance and coupled with an electromagnetically (EM) tracked delivery system for intravascular navigation. Numerical feedback for controlling the endograft landing zone distance and ostial alignment was holographically projected on the operative field. Visualization of the holograms was provided via a commercially available AR headset. A Zenith Spiral-Z AAA limb stent-graft was modified with a scallop, 6 degree-of-freedom EM sensor for tracking, and radiopaque markers for fluoroscopic visualization. In vivo, 10 interventionalists independently positioned and oriented the delivery system to the ostia of renal or visceral branch vessels in anesthetized swine via open femoral artery access using 3D-GNC and standard fluoroscopic guidance. Procedure time, fluoroscopy time, cumulative air kerma, and contrast material volume were recorded for each technique. Positioning and orientation accuracy was determined by measuring the target landing-zone distance error (δLZE) and the scallop-ostium angular alignment error (θSOE) using contrast-enhanced cone beam computed tomography imaging after each positioning for each technique. Mean, standard deviation, and standard error are reported for the performance variables, and Student's t tests were used to evaluate statistically significant differences in performance mean values of 3D-GNC and fluoroscopy. RESULTS: Technical success for the use of 3D-GNC to orient and position the endovascular device at each renal-visceral branch ostium was 100%. 3D-GNC resulted in 56% decrease in procedure time in comparison with standard fluoroscopic guidance (p<0.001). The 3D-GNC system was used without fluoroscopy or contrast-dye administration. Positioning accuracy was comparable for both techniques (p=0.86), while overall orientation accuracy was improved with the 3D-GNC system by 41.5% (p=0.008). CONCLUSIONS: The holographic 3D-GNC system demonstrated improved accuracy of aortic stent-graft positioning with significant reductions in fluoroscopy time, contrast-dye administration, and procedure time.

Evaluation of an augmented reality navigational guidance platform for percutaneous procedures in a cadaver model.

Purpose: The objective of this study is to review the accuracy of an augmented reality navigational guidance system designed to facilitate improved visualization, guidance, and accuracy during percutaneous needle-based procedures including biopsies and ablations. Approach: Using the HoloLens 2, the system registers and projects 3D CT-based models of segmented anatomy along with live ultrasound, fused with electromagnetically tracked instruments including ultrasound probes and needles, giving the operator comprehensive stereoscopic visualization for intraoperative planning and navigation during procedures.Tracked needles were guided to targets implanted in a cadaveric model using the system. Image fusion registration error, the multimodality error measured as the post-registration distance between a corresponding point measured in the stereoscopic CT and tracked ultrasound coordinate systems, and target registration error, the Euclidean distance between needle tip and target after needle placement, were measured as registration and targeting accuracy metrics. A t-distribution was used for statistical analysis. Results: Three operators performed 36 total needle passes, 18 to measure image fusion registration error and 18 to measure target registration error on four targets. The average depth of each needle pass was 8.4 cm from skin to target center. Mean IFRE was 4.4 mm (H0: µ=5 mm, P<0.05). Mean TRE was 2.3 mm (H0: µ=5 mm, P<0.00001). Conclusions: The study demonstrated high registration and targeting accuracy of this AR navigational guidance system in percutaneous, needle-based procedures. This suggests the ability to facilitate improved clinical performance in percutaneous procedures such as ablations and biopsies.