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Neumann M.,Laboratoire Des Science Of Limage
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2012

In this paper, an original workflow is presented for MR image plane alignment based on tracking in real-time MR images. A test device consisting of two resonant micro-coils and a passive marker is proposed for detection using image-based algorithms. Micro-coils allow for automated initialization of the object detection in dedicated low flip angle projection images; then the passive marker is tracked in clinical real-time MR images, with alternation between two oblique orthogonal image planes along the test device axis; in case the passive marker is lost in real-time images, the workflow is reinitialized. The proposed workflow was designed to minimize dedicated acquisition time to a single dedicated acquisition in the ideal case (no reinitialization required). First experiments have shown promising results for test-device tracking precision, with a mean position error of 0.79 mm and a mean orientation error of 0.24°. Source

Seitel A.,German Cancer Research Center | Engel M.,German Cancer Research Center | Sommer C.M.,University of Heidelberg | Radeleff B.A.,University of Heidelberg | And 7 more authors.
Medical Physics | Year: 2011

Purpose: Computed tomography (CT) guided minimally invasive interventions such as biopsies or ablation therapies often involve insertion of a needle-shaped instrument into the target organ (e.g., the liver). Today, these interventions still require manual planning of a suitable trajectory to the target (e.g., the tumor) based on the slice data provided by the imaging modality. However, taking into account the critical structures and other parameters crucial to the success of the intervention-such as instrument shape and penetration angle-is challenging and requires a lot of experience. Methods: To overcome these problems, we present a system for the automatic or semiautomatic planning of optimal trajectories to a target, based on 3D reconstructions of all relevant structures. The system determines possible insertion zones based on so-called hard constraints and rates the quality of these zones by so-called soft constraints. The concept of pareto optimality is utilized to allow for a weight-independent proposal of insertion trajectories. In order to demonstrate the benefits of our method, automatic trajectory planning was applied retrospectively to n 10 data sets from interventions in which complications occurred. Results: The efficient (graphics processing unit-based) implementation of the constraints results in a mean overall planning time of about 9 s. The examined trajectories, originally chosen by the physician, have been rated as follows: in six cases, the insertion point was labeled invalid by the planning system. For two cases, the system would have proposed points with a better rating according to the soft constraints. For the remaining two cases the system would have indicated poor rating with respect to one of the soft constraints. The paths proposed by our system were rated feasible and qualitatively good by experienced interventional radiologists. Conclusions: The proposed computer-assisted trajectory planning system is able to detect unsafe and propose safe insertion trajectories and may especially be helpful for interventional radiologist at the beginning or during their interventional training. © 2011 American Association of Physicists in Medicine. Source

Lagouarde J.-P.,French National Institute for Agricultural Research | Bach M.,French National Center for Space Studies | Sobrino J.A.,University of Valencia | Boulet G.,French National Center for Space Studies | And 13 more authors.
International Journal of Remote Sensing | Year: 2013

This article presents the MISTIGRI project of a microsatellite developed by the French space agency Centre National d'Etudes Spatiales (CNES) in cooperation with Spain (Image Processing Laboratory of the University of Valencia and Centro para el Desarrollo Tecnológico Industrial (CDTI)). MISTIGRI is a mission that has the originality of combining a high spatial resolution (~50 m) with a daily revisit in the thermal infrared (TIR). MISTIGRI is an experimental mission devoted to demonstrate the potential of such TIR data for future operational missions. The scientific goals and expected applications of the mission are described: they encompass the monitoring of (i) agricultural areas and related hydrological processes, (ii) urban areas, and (iii) coastal areas and continental waters. Then, the specifications on spatial resolution, revisit frequency, overpass time, and spectral configuration are justified. The strategy of the mission is based on the combination with a network of long-term experimental sites. It will also make possible observing some areas facing rapid climatic change. The choice of the orbit is presented. Finally, we give rapid overviews of both the instrumental concept and the proposed mission architecture. © 2013 Copyright Taylor and Francis Group, LLC. Source

Alby E.,Laboratoire Des Science Of Limage | Smigiel E.,Laboratoire Des Science Of Limage | Assali P.,Laboratoire Des Science Of Limage
Revue Francaise de Photogrammetrie et de Teledetection | Year: 2011

Leaning against a hill, it has a diameter of 142 meters and its capacity is estimated between 15,000 and 18,000 seats. These features make it the second largest theater in Gaul (behind Autun). The digitization of such a building is a means to deepen the knowledge of its geometrical characteristics thanks to the analysis tools on the one hand, but to document the scene in its current configuration on the other. Collaboration between the unit of study of ancient civilizations at the University of Strasbourg and the group of Photogrammetry and Geomatics was established to carry out this digitization project. From its dimensions, the three-dimensional data acquisition by terrestrial laser scanner is needed. Many holes do not permit a complete documentation using laser scanning; the data set has been completed by photogrammetry. The emergence of new tools for correlation from stereo pairs provides data of same kind and quality. The complete digitization of the theater thus requires the combination of both techniques. As part of the development of the theater, but also to validate the assumptions of archaeological restoration, modeling an original state has been completed. It is by confrontation of hypotheses with data from the field it is possible to represent the scene as it is supposed to have looked like at the time of its construction. Source

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