Special issue on biomechanical and Parametric Modelling of Human Anatomy (PMHA-2016)

The 4th annual workshop on Parametric Modelling of Human Anatomy (PMHA-2016) was held Aug 26–27, 2016 in Vancouver, Canada. The international workshop brought together Computer Scientists, Dentists, Engineers, Linguists, Anatomists, Oro-facial Surgeons, among others, to share techniques and approaches to modelling the biomechanics of the human body and applying these models to new biomedical and human-factor applications. Continuing the tradition of the annual Parametric Modelling of Human Anatomy (PMHA) workshop series, this special issue of the journal Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization (CMBBE: Imaging & Visualization) consists of five papers drawn from research introduced at PMHA-2016. These articles were reviewed according to the CMBBE: Imaging & Visualization policy. This year’s PMHA workshop included 30 excellent presentations covering both technical and clinical aspects of biomechanical modelling of human anatomy with a focus on head and neck anatomy, as is the tradition. Sessions were organised around the following topics: (1) Speech Measurement, (2) Swallowing Simulation, (3) Muscle Modelling, (4) General Modelling & Measurement Techniques and (5) Finite-Element Modelling and Model Registration Methods. As in previous years, discussion topics included: measuring structural anatomy through magnetic resonance imaging (MRI) and x-ray computed tomography (CT); measuring functional movements through dynamic MRI, video fluoroscopy, optical motion analysis, simulating fluid flow for swallowing and speech production; and simulating musculoskeletal dynamics of the neck, spine and lower limb; simulating tissue mechanics for the tongue, soft-palate and upper extremity; and visualising anatomy with 3D rendering, 3D atlases and virtual reality. A preworkshop tutorial on advanced biomechanical modelling with the ArtiSynth toolkit (www.artisynth.org) was also held for participants the day before the workshop. Participants in the tutorial were given a hands-on experience for getting new models up and running in ArtiSynth as well as integrating their own clinical data with simulations. From the diverse set of research presented at PMHA-2016, five papers were chosen for this special issue that focus on advances in visualisation and simulation of anatomical systems. Woo et al., present a novel approach to anatomical visualisation with a multimodal atlas of 4D tongue motion. This work extends previous 3D atlases of tongue shape by including multimodal and dynamic information for speech movements. A number of data processing steps are detailed to transform raw cineand tagged-MRI data from multiple subjects, into a coherent atlas-based dataset. The authors propose a number of new low dimensional representations, enabled through the SpeechMap atlas, to succinctly characterise lingual speechmovements. The study also shows how these representations can be used in a clinical setting to compare movement patterns between glossectomy patients and healthy volunteers. Following the same topic of anatomical visualisation, papers by Michiwaki et al. and Kamiya et al. investigate dynamic visualisations of the vocal tract, but in the context of swallowing instead of speech. Michiwaki et al. provide a general overview of their SwallowVision simulation and visualisation software platform. They also report the details of their approach for visualising vocal tract organs during swallowing based on CT and video-fluoroscopy imaging. Image-driven models were generated for a healthy volunteer as well as a dysphagia patient in order to provide a clinical context for the visualisations. Kamiya et al. focus on visualising the physical characteristics of the food bolus during swallowing events. Food bolus visualisation is challenging due to the heterogeneous consistency and fast motion of the bolus during swallowing. The authors address these challenges by employing a mesh-less 3D moving particle simulation of the bolus. Together with the image-driven simulations in SwallowVision, the physics-driven bolus simulations were used to visualise differences in shear rate and viscosity for different bolus materials. Continuing in a similar vein as the SwallowVision papers, Wang et al., also report a novel approach to swallowing simulation and visualisation. This paper has a strong clinical focus, and a unique demonstration of how modelling methods can be used to inform clinical decision-making for dysphagia. The authors investigate the consequences of tongue surgery, and specifically the loss of tissue at the base of tongue, on swallowing biomechanics through simulation. A virtual swallowing model was developed within the ArtiSynth simulation platform, based upon CT scans of an oropharyngeal cancer patient that underwent tongue surgery. By coupling the dynamic anatomical model of swallowing with a fluid model for the bolus, simulations were able to generate ‘swallowing assessments’ similar to those used in clinical practice. This work lays