Towards Transcervical Ultrasound Image Guidance for Transoral Robotic Surgery

Purpose: Trans-oral robotic surgery (TORS) using the da Vinci surgical robot is a new minimally-invasive surgery method to treat oropharyngeal tumors, but it is a challenging operation. Augmented reality (AR) based on intra-operative ultrasound (US) has the potential to enhance the visualization of the anatomy and cancerous tumors to provide additional tools for decision-making in surgery. Methods: We propose and carry out preliminary evaluations of a US-guided AR system for TORS, with the transducer placed on the neck for a transcervical view. Firstly, we perform a novel MRI-transcervical 3D US registration study. Secondly, we develop a US-robot calibration method with an optical tracker and an AR system to display the anatomy mesh model in the real-time endoscope images inside the surgeon console. Results: Our AR system reaches a mean projection error of 26.81 and 27.85 pixels for the projection from the US to stereo cameras in a water bath experiment. The average target registration error for MRI to 3D US is 8.90 mm for the 3D US transducer and 5.85 mm for freehand 3D US, and the average distance between the vessel centerlines is 2.32 mm. Conclusion: We demonstrate the first proof-of-concept transcervical US-guided AR system for TORS and the feasibility of trans-cervical 3D US-MRI registration. Our results show that trans-cervical 3D US is a promising technique for TORS image guidance.Comment: 12 pages, 8 figures. Accepted by Information Processing for Computer Assisted Interventions (IPCAI 2023

Adaptation and Mal-Adaptation to Ambient Hypoxia; Andean, Ethiopian and Himalayan Patterns

The study of the biology of evolution has been confined to laboratories and model organisms. However, controlled laboratory conditions are unlikely to model variations in environments that influence selection in wild populations. Thus, the study of “fitness” for survival and the genetics that influence this are best carried out in the field and in matching environments

The performance of deterministic and stochastic interest rate risk measures : Another Question of Dimensions?

The efficiency of traditional and stochastic interest rate risk measures is compared under one-, two-, and three-factor no-arbitrage Gauss-Markov term structure models, and for different immunization periods. The empirical analysis, run on the German Treasury bond market from January 2000 to December 2010, suggests that: i) Stochastic interest rate risk measures provide better portfolio immunization than the Fisher-Weil duration; and ii) The superiority of the stochastic risk measures is more evident for multi-factor models and for longer investment horizons. These findings are supported by a first-order stochastic dominance analysis, and are robust against yield curve estimation errors.info:eu-repo/semantics/publishedVersio

The value of preoperative mandibular plating in reconstruction of the mandible

Background: This study evaluates the efficacy of preoperative versus intraoperative mandibular contouring using rapid prototyping technology. Methods: 10 patients requiring mandibular reconstruction had a preoperative mandibular plate contoured to a fabricated three-dimensional mandibular model based on preoperative imaging. A traditional intraoperative plate was also contoured. Two blinded surgeons compared the plates with respect to conformance, surface-area contact, and best overall match. A cost-benefit analysis was then performed. Results: The average time to contour was 867+/-243 seconds and 833+/-289 seconds for the preoperative and intraoperative plates respectively(p=0.83). Inter-observer analysis revealed no statistically significant differences in conformance(p=0.38) or surface area contact(p=0.14). In 7/9 cases, the preoperative plate was selected for the final reconstruction. In one case, an intraoperative plate was not contoured due to the lateral extent of the tumor. Conclusions: In cases of mandibular distortion secondary to disease, pathologic fracture or defects involving multiple mandibular subsites this method is particularly advantageous. © 2013 Wiley Periodicals, Inc. Head Neck, 2013