Osteochondral lesion of the talus: still a problem?

Osteochondral lesion of the talus (OLT) often occurs after ankle trauma or repetitive micro-traumata, whereas the actual etiology remains unclear. The most common symptoms are local pain deep in the medial or lateral ankle that increases with weight-bearing and activity, accompanied by tenderness and swelling. Eventually, most patients with symptomatic or unstable OLT require surgery. Many reasonable operative techniques have been described, whereas most lead to similar and satisfactory results. They can be divided into cartilage repair, cartilage regeneration and cartilage replacement techniques. The OLT size and morphology in the first place but also surgeon and individual patient aspects are considered when it comes to surgery. For high postoperative success and low recurrence rates, underlying causes, for example, ligamentous instability and hindfoot malalignment should also be addressed during surgery

Evaluation of WiseMAC and extensions onwireless sensornodes

In the past five years, many energy-efficient medium access protocols for all kinds of wireless networks (WSNs) have been proposed. Some recently developed protocols focus on sensor networks with low traffic requirements are based on so-called preamble sampling or low-power listening. The WiseMAC protocol is one of the first of this kind and still is one of the most energy-efficient MAC protocols for WSNs with low or varying traffic requirements. However, the high energy-efficiency of WiseMAC has shown to come at the cost of a very limited maximum throughput. In this paper, we evaluate the properties and characteristics of a WiseMAC implementation in simulation and on real sensor hardware. We investigate on the energy-consumption of the prototype using state-of-the-art evaluation methodologies. We further propose and examine an enhancement of the protocol designed to improve the traffic-adaptivity of WiseMAC. By conducting both simulation and real-world experiments, we show that the WiseMAC extension achieves a higher maximum throughput at a slightly increased energy cost both in simulation and real-world experiment

Parametric spherical deconvolution: Inferring anatomical connectivity using diffusion MR imaging

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Neuroanatomical prerequisites for language functions in the maturing brain

The 2 major language-relevant cortical regions in the human brain, Broca's area and Wernicke's area, are connected via the fibers of the arcuate fasciculus/superior longitudinal fasciculus (AF/SLF). Here, we compared this pathway in adults and children and its relation to language processing during development. Comparison of fiber properties demonstrated lower anisotropy in children's AF/SLF, arguing for an immature status of this particular pathway with conceivably a lower degree of myelination. Combined diffusion tensor imaging (DTI) data and functional magnetic resonance imaging (fMRI) data indicated that in adults the termination of the AF/SLF fiber projection is compatible with functional activation in Broca's area, that is pars opercularis. In children, activation in Broca's area extended from the pars opercularis into the pars triangularis revealing an alternative connection to the temporal lobe (Wernicke's area) via the ventrally projecting extreme capsule fiber system. fMRI and DTI data converge to indicate that adults make use of a more confined language network than children based on ongoing maturation of the structural network. Our data suggest relations between language development and brain maturation and, moreover, indicate the brain's plasticity to adjust its function to available structural prerequisites

A comparison of methods for the registration of tractographic fibre images

Diffusion tensor imaging (DTI) and tractography have opened up new avenues in neuroscience. As most applications require precise spatial localization of the fibre images, image registration is an important area of research. Registration is usually performed prior to tractography. However more reliable images could be produced if a viable registration can be performed post tractography. This study shows two available techniques for direct registration of fibre images and explores novel adaptations of these. The methods register volume images derived from the fibres, and reapply the transformation from these registrations to the fibre images. The first method is a local affine registration and the second is a global affine registration. The local affine method produced superior results

Beyond fractional anisotropy: Extraction of bundle-specific structural metrics from crossing fiber models

Diffusion MRI (dMRI) measurements are used for inferring the microstructural properties of white matter and to reconstruct fiber pathways. Very often voxels contain complex fiber configurations comprising multiple bundles, rendering the simple diffusion tensor model unsuitable. Multi-compartment models deliver a convenient parameterization of the underlying complex fiber architecture, but pose challenges for fitting and model selection. Spherical deconvolution, in contrast, very economically produces a fiber orientation density function (fODF) without any explicit model assumptions. Since, however, the fODF is represented by spherical harmonics, a direct interpretation of the model parameters is impossible. Based on the fact that the fODF can often be interpreted as superposition of multiple peaks, each associated to one relatively coherent fiber population (bundle), we offer a solution that seeks to combine the advantages of both approaches: first the fiber configuration is modeled as fODF represented by spherical harmonics and then each of the peaks is parameterized separately in order to characterize the underlying bundle. In this work, the fODF peaks are approximated by Bingham distributions, capturing first and second-order statistics of the fiber orientations, from which we derive metrics for the parametric quantification of fiber bundles. We propose meaningful relationships between these measures and the underlying microstructural properties. We focus on metrics derived directly from properties of the Bingham distribution, such as peak length, peak direction, peak spread, integral over the peak, as well as a metric derived from the comparison of the largest peaks, which probes the complexity of the underlying microstructure. We compare these metrics to the conventionally used fractional anisotropy (FA) and show how they may help to increase the specificity of the characterization of microstructural properties. While metric relying on the first moments of the Bingham distributions provide relatively robust results, second-order metrics representing the peak spread are only meaningful, if the SNR is very high and no fiber crossings are present in the voxel