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.

Mixed Reality and 3D Printed Models for Planning and Execution of Face Transplantation.

OBJECTIVE: The aim of this study was to evaluate a novel holographic craniofacial surgical planning application and its implementation throughout the planning and operative stages of facial transplantation by performing a critical analysis of comparative utility, cost, and limitations of MR and 3D printing. SUMMARY OF BACKGROUND DATA: Face transplantation is a highly complex form of craniofacial reconstruction requiring significant planning, knowledge of patient-specific spatial relationships, and time-sensitive decision making. Computer-aided 3D modeling has improved efficiency and outcomes of complex craniofacial reconstruction by enabling virtual surgical planning and 3D printed model generation. MR technology can enhance surgical planning, improve visualization, and allow manipulation of virtual craniofacial biomodels within the operative field. METHODS: Accounting for the time-sensitive nature of face transplantation, a unique, highly coordinated workflow for image acquisition and processing was designed to facilitate rapid holographic rendering and 3D printing. During recent face transplantation, both holographic and 3D printed models were utilized, and the time and cost of fabrication were compared. RESULTS: Holographic models required less time and cost for fabrication. They provided both comprehensive visualization of 3D spatial relationships and novel means to perform VSP and virtual face transplantation by interacting with and manipulating patient-specific, anatomic holograms. CONCLUSION: Time efficiency, low-cost biomodel production, provision of unlimited preoperative surgical rehearsal, and potential for intraoperative surgical guidance makes holographic VSP and MR highly promising technology for use in complex craniofacial surgery.

Beyond the aortic bifurcation: branched endovascular grafts for thoracoabdominal and aortoiliac aneurysms.

OBJECTIVES: To evaluate the use of novel technology to treat complex aortic aneurysms involving branches that provide critical end-organ blood supply. METHODS: A prospective study was conducted in patients with thoracoabdominal, suprarenal, or common iliac aneurysms (TAA, SRA, or CIA) at high risk for open surgical repair. An endovascular graft using the Zenith platform was customized to fit patient anatomy (TAA or SRA) and combined with Jomed balloon-expandable stent-grafts. Prefabricated hypogastric branches were used with a Zenith abdominal aortic aneurysm (AAA) or Fluency self-expanding fenestrated device in conjunction with a self-expanding stent-graft. Analyses were conducted in accordance with the endovascular aneurysm reporting standards document. Follow-up studies occurred at discharge, 1, 6, and 12 months, and included computed tomography and duplex ultrasound scans, and flat plate radiography. RESULTS: Fifty patients were treated (9 TAA, 20 SRA, 21 CIA). The mean aneurysm size was 7.6 cm (TAA), 7.2 cm (SRA), and 6.1 cm AAA size associated with a mean CIA size of 3.8 cm. Bilateral CIA aneurysms were present in 86% (18/21) of patients with CIA aneurysms. Perioperative mortality was 2% (1/50) and resulted from a myocardial infarction after a planned conduit and iliac endarterectomy required for device access. Five late deaths occurred (2 TAA, 2 SRA, 1 CIA), three of which (2 TAA, 1 SRA) were aneurysm related. Failure to access internal iliac arteries occurred in three cases, and two late hypogastric branch thromboses occurred. No visceral branches were lost acutely or occluded during follow-up. Sac shrinkage (>5 mm) was noted in 65% of patients at 6 months and in all patients (10/10) by 12 months. There were no ruptures or conversions, but nine patients required secondary interventions. CONCLUSIONS: Branch vessel technology has made it technically feasible to preserve critical end-organ perfusion in the setting of CIA, SRA, and TAA aneurysms. The relatively low acute mortality rate and lack of short-term branch vessel loss are encouraging and merit further investigation. These advances have the potential to markedly diminish the complications associated with conventional management of complex aneurysms.