Academic radiology
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Most methods used in functional MRI (fMRI) brain mapping require restrictive assumptions about the shape and timing of the fMRI signal in activated voxels. Consequently, fMRI data may be partially and misleadingly characterized, leading to suboptimal or invalid inference. To limit these assumptions and to capture the broad range of possible activation patterns, a novel statistical fMRI brain mapping method is proposed. It relies on hidden semi-Markov event sequence models (HSMESMs), a special class of hidden Markov models (HMMs) dedicated to the modeling and analysis of event-based random processes. ⋯ All the experiments performed on synthetic and real fMRI data demonstrate the relevance of HSMESMs in fMRI brain mapping. In particular, the statistical character of these models, along with their learning and generalizing abilities are of particular interest when dealing with strong variabilities of the active fMRI signal across time, space, experiments, and subjects.
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A reduction in cartilage volume is characteristic of osteoarthritis and hence there exists a need for an accurate and reproducible method to measure in vivo cartilage volume. Quantification of cartilage volume from magnetic resonance (MR) images requires a segmentation technique such as the user-driven "Live Wire" strategy that can reliably delineate object volumes in a time-efficient manner. In the present work, the accuracy and reproducibility of the Live Wire method for the quantification of cartilage volume in MR images is evaluated. ⋯ The data suggest that the Live Wire strategy is an accurate, reproducible, and efficient technique to measure cartilage volume in vivo in a feasible amount of operator time.
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An artificial neural network (ANN)-based segmentation method was developed for dynamic contrast-enhanced magnetic resonance (MR) imaging of the breast and compared with quantitative and empiric parameter mapping techniques. ⋯ ANN is capable of classifying breast lesions on MR images. Mapping correlation coefficient, k(ep) and time-to-peak showed the highest association with the ANN result.
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Comparative Study
Sagittal reformations of volumetric inspiratory and expiratory high-resolution CT of the lung.
The purpose of this study is to determine whether sagittal reformations of volumetric high-resolution computed tomography (CT) provide additional information in evaluating lung abnormalities compared to axial high-resolution CT images. ⋯ Sagittal reformatted images of volumetric high-resolution CT provided additional information compared to volumetric axial images alone with statistical significance.
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The purpose of this study is to quantify the impact of clinical consultation on the workload of an academic emergency radiology section. ⋯ Clinical consultation represents a significant portion of the workload in academic emergency radiology. The consultation fraction describes the fraction of the radiologist's time spent in consultation, and the CVU/FTE expresses the workload of clinical consultations in terms of wRVU/FTE, the factor used most commonly to determine the academic radiologist's productivity and staffing.