Soft-tissue simulation of the breast for intraoperative navigation and fusion of preoperative planning.

Computational preoperative planning offers the opportunity to reduce surgery time and patient risk. However, on soft tissues such as the breast, deviations between the preoperative and intraoperative settings largely limit the applicability of preoperative planning. In this work, we propose a high-performance accurate simulation model of the breast, to fuse preoperative information with the intraoperative deformation setting. Our simulation method encompasses three major elements: high-quality finite-element modeling (FEM), efficient handling of anatomical couplings for high-performance computation, and personalized parameter estimation from surface scans. We show the applicability of our method on two problems: 1) transforming high-quality preoperative scans to the intraoperative setting for fusion of preoperative planning data, and 2) real-time tracking of breast tumors for navigation during intraoperative radiotherapy. We have validated our methodology on a test cohort of nine patients who underwent tumor resection surgery and intraoperative radiotherapy, and we have quantitatively compared simulation results to intraoperative scans. The accuracy of our simulation results suggest clinical viability of the proposed methodology.

Weight of Evidence: Participatory Methods and Bayesian Updating to Contextualize Evidence Synthesis in Stakeholders' Knowledge.

Mixed methods research is well-suited to grapple with questions of what counts as valid knowledge across different contexts and perspectives. This article introduces Weight of Evidence as a transformative procedure for stakeholders to interpret, expand on and prioritize evidence from evidence syntheses, with a focus on engaging populations historically excluded from planning and decision making. This article presents the procedure's five steps using pilot data on perinatal care of immigrant women in Canada, engaging family physicians and birth companions. Fuzzy cognitive mapping offers an accessible and systematic way to generate priors to update published literature with stakeholder priorities. Weight of Evidence is a transparent procedure to broaden what counts as expertise, contributing to a more comprehensive, context-specific, and actionable understanding.

Soft-Tissue Simulation for Computational Planning of Orthognathic Surgery.

Simulation technologies offer interesting opportunities for computer planning of orthognathic surgery. However, the methods used to date require tedious set up of simulation meshes based on patient imaging data, and they rely on complex simulation models that require long computations. In this work, we propose a modeling and simulation methodology that addresses model set up and runtime simulation in a holistic manner. We pay special attention to modeling the coupling of rigid-bone and soft-tissue components of the facial model, such that the resulting model is computationally simple yet accurate. The proposed simulation methodology has been evaluated on a cohort of 10 patients of orthognathic surgery, comparing quantitatively simulation results to post-operative scans. The results suggest that the proposed simulation methods admit the use of coarse simulation meshes, with planning computation times of less than 10 seconds in most cases, and with clinically viable accuracy.