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Postural control can be a challenging task for many people, including those with cerebral palsy or idiopathic scoliosis. Assessment of postural stability can be used as one element of a comprehensive strategy to identify more efficient treatments and can provide a better understanding of postural control deficits. Several models and techniques have been developed to assess and understand postural...
Cranioplasty is a commonly performed procedure. Outcomes can be improved by the use of patient specific implants, however, high costs limit their accessibility. This paper presents a low cost alternative technique to create patient specific polymethylmethacrylate (PMMA) implants using rapid prototyped mold template. We used available patient's CT-scans, one dataset without craniotomy and one with...
Accurate estimation of the human head conductivity is important for the diagnosis and therapy of brain diseases. Induced Current - Magnetic Resonance Electrical Impedance Tomography (IC-MREIT) is a recently developed non-invasive technique for conductivity estimation. This paper presents a formulation where a low number of material parameters need to be estimated, starting from MR eddy-current field...
F-wave persistence is a frequently reported parameter for nerve conduction studies. F-wave activities are generated through backfiring of motor neurons. F-wave persistence is designed to estimate the backfiring rate. Through computational models and probability analyses, we demonstrated that the F-wave persistence definition is deficient in providing a robust and consistent estimate of the backfiring...
This paper develops a method to determine the minimum duration interval which ensures that the process of “sorting” the extracellular action potentials recorded during that interval achieves a desired confidence level of accuracy. During the recording process, a sequential decision theory approach continually evaluates a variant of the likelihood ratio test using the model evidence of the sorting/clustering...
The focus of this paper is to present a method utilizing lung sounds for a quantitative assessment of patient health as it relates to respiratory disorders. In order to accomplish this, applicable traditional techniques within the speech processing domain were utilized to evaluate lung sounds obtained with a digital stethoscope. Traditional methods utilized in the evaluation of asthma involve auscultation...
The cardiac Monodomain model is a mathematical model extensively used in studies of propagation of bioelectric wavefronts in the heart. To be able to use the model for complex and large cardiac simulations, such as the case of whole heart and 3D simulations, some parameters of the model that are known to physiologically vary in space, such as the intracellular conductivity, are traditionally kept...
A novel approach is proposed for generating data driven models of the lung nodules appearing in low dose CT (LDCT) scans of the human chest. Four types of common lung nodules are analyzed using Active Appearance Model methods to create descriptive lung nodule models. The proposed approach is also applicable for automatic classification of nodules into pathologies given a descriptive database. This...
We compare the results given by different methods to reconstruct cortical sources activity in order to classify EEG in real time. Two motor imagery experiments were performed. The aim was to retrieve from 1-second windows of signal which motor imagery task the subjects were performing. The use of cortical activity reconstruction was compared to Laplacian filtering, which is often used in BCI. A recursive...
In this paper, the interaction force between a surgical needle and soft tissue is studied. The force is modeled using nonlinear dynamics based on a modified LuGre model that captures all stages of needle-tissue interaction including puncture, cutting, and friction forces. An estimation algorithm for identifying the associated parameters is then presented. This approach, which is based on extended...
Clustering can be a valuable tool for analyzing large amounts of data, but anyone who clusters must choose how many item clusters, K, to report. Unfortunately, one must guess at K or some related parameter when working within each of the three available frameworks where one thinks of clustering: as a Euclidean distance problem; as a statistical model problem; or as a complexity theory problem. We...
Cardiovascular diseases are the major cause of death in the developed countries. Identifying key cellular processes involved in generation of the electrical signal and in regulation of signal transduction pathways is essential for unraveling the underlying mechanisms of heart rhythm behavior. Computational cardiac models provide important insights into cardiovascular function and disease. Sensitivity...
We present a new approach for the investigation of Granger causality in the frequency domain by means of the partial directed coherence (PDC). The approach is based on the utilization of an extended multivariate autoregressive (MVAR) model, including instantaneous effects in addition to the lagged effects traditionally studied, to fit the observed multiple time series prior to PDC computation. Model...
Radiofrequency (RF) ablation uses RF current to heat and kill cancer applied via an electrode inserted under image-guidance, and is in clinical use for tumors in liver, lung kidney, and bone. Mathematical models are frequently used to determine tissue temperature during RF ablation, but most prior models do not include accurate implementation of power control algorithms as are used in clinical devices...
Compensating for cardio-thoracic motion artifacts in contrast-enhanced cardiac perfusion MRI (p-MRI) sequences is a key issue for the quantitative assessment of myocardial iscæmia. The classical paradigm consists of registering each sequence frame on some reference using an intensity-based matching criterion. In this paper, we present a novel unsupervised method for the groupwise registration of cardiac...
The Modeling Markup Language (MML) framework is a conceptual paradigm to quickly develop and solve biological models utilizing the CellML specification. In this study, we present the open source toolkit developed for this project and a possible workflow to create different scales of cardiac tissue models from a range of CellML models. Models from the CellML repository and other sources were tested...
Drug bioavailability is a major failing point of new pharmaceuticals i.e. drugs fail to reach their target or fail to stay there long enough for therapeutic effect. Compounding this issue, significant variability exists between patients and how they metabolize and distribute a drug. We present WebPK, a web-based tool for simulation of custom pharmacokinetic models. Model parameters can be entered...
The geometry of conduits derived from in vivo image data is subject to acquisition and reconstruction errors. This results in a degree of uncertainty in defining the bounding geometry for a patient-specific anatomical conduit. The impact of the conduit geometry uncertainty should be considered with respect to haemodynamic clinically relevant measures that may alter the perception and evaluation of...
Most conventional computer-aided navigation systems assist the surgeon visually by tracking the position of an ancillary and by superposing this position into the 3D preoperative imaging exam. This paper aims at adding to such navigation systems a device that will guide the surgeon towards the target, following a complex preplanned ancillary trajectory. We propose to use tactile stimuli for such guidance,...
The management and follow-up of chronic type B aortic dissections continues being a clinical challenge. Patients with chronic type B dissection have high mid/long term mortality mainly due to progressive aortic dilatation and subsequent rupture. To predict further dilatation, guidelines suggest follow-up of the total aortic diameter. However, dilatation is triggered by haemodynamic parameters (intra-luminal...
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