Comprehensive patient-specific information preprocessing for cardiac surgery simulations.

PURPOSE: Patient-specific biomechanical simulations of the behavior of soft tissue gain importance in current surgery assistance systems as they can provide surgeons with valuable ancillary information for diagnosis and therapy. In this work, we aim at supporting minimally invasive mitral valve reconstruction (MVR) surgery by providing scenario setups for FEM-based soft tissue simulations, which simulate the behavior of the patient-individual mitral valve subject to natural forces during the cardiac cycle after an MVR. However, due to the complexity of these simulations and of their underlying mathematical models, it is difficult for non-engineers to sufficiently understand and adequately interpret all relevant modeling and simulation aspects. In particular, it is challenging to set up such simulations in automated preprocessing workflows such that they are both patient-specific and still maximally comprehensive with respect to the model. METHODS: In this paper, we address this issue and present a fully automated chain of preprocessing operators for setting up comprehensive, patient-specific biomechanical models on the basis of patient-individual medical data. These models are suitable for FEM-based MVR surgery simulation. The preprocessing methods are integrated into the framework of the Medical Simulation Markup Language and allow for automated information processing in a data-driven pipeline. RESULTS: We constructed a workflow for holistic, patient-individual information preprocessing for MVR surgery simulations. In particular, we show how simulation preprocessing can be both fully automated and still patient-specific, when using a series of dedicated MVR data analytics operators. The outcome of our operator chain is visualized in order to help the surgeon understand the model setup. CONCLUSION: With this work, we expect to improve the usability of simulation-based MVR surgery assistance, through allowing for fully automated, patient-specific simulation setups. Combined visualization of the biomechanical model setup and of the corresponding surgery simulation results fosters the understandability and transparency of our assistance environment.

[Self-inflicted injuries by injecting contaminated solutions through the chest wall (author's transl)]. / Selbstbeschädigung durch Verabreichung von infektiösem Material durch die Brustwand

In the case of three prisoners, we observed the results of their attempt to induce an infection of the pleura and lungs by injecting themselves through the chest wall with a contaminated substance in order that they might be transferred to a sanatorium. Traces of the solution they had administered, which among other substances contained faeces, were found in the chest wall, in the pleural and subphrenic area, in the lungs and in the liver. The self-inflicted injuries described, led in the case of one of the prisoners to his death following a subphrenic abscess, a necrosis and abscess of the liver, septic shock and respiratory insufficiency. The clinically recognizable results of the injection only set in after a period of latency of several days. In one case there were still traces of stool in the liver 24 days after its initial introduction.