Patient-specific 4D Virtual Reality Simulation of Punctures and Radiofrequency Ablations in Breathing Virtual Body Models

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In this project, methods for realistic visuo-haptic virtual reality simulation of respiratory motion in virtual patient models are developed. Areas of application are patient-specific planning and training of punctures and radiofrequency ablations (RFA) under respiratory motion. For static 3D image data of a new patient, individual as well as mean 4D motion models are transferred, which have been extracted from 4D image data and serve as voxel-related descriptions of real respiratory motion. By using surrogate-based 4D motion models, the variability of respiration is simulated realistically in different respiratory cycles. The anatomical differences between the anatomy of the model and the patient are compensated and the 4D motion of organs is transferred for animation onto the static 3D patient image data by means of non-linear registration methods. The 4D motion models are integrated into a visuo-haptic framework, which enables the visuo-haptic interaction of the puncture or ablation needle with the breathing virtual patient model. For the real-time 4D visualization of animated 3D image data, special volume-based 4D rendering techniques are developed and highly parallelized on the GPU. Additionally, for needle punctures and RFA, the effects on 4D path planning and biophysical simulation of RFA caused by respiratory motion are compared to planning and simulating by using static 3D image data. Apart from evaluation of the separate methods and components, a user evaluation of the whole VR training simulator for RF ablations including respiratory motion is carried out.