Model of a Vascular C-Arm for 3D Augmented Fluoroscopy in Interventional Radiology

International audienceThis paper deals with the modeling of a vascular C-arm to generate 3D augmented fuoroscopic images in an interventional radiology context. A methodology based on the use of a multi-image calibration is proposed to assess the physical behavior of the C-arm. From the knowledge of the main characteristics of the C-arm, realistic models of the acquisition geometry are proposed. Their accuracy was evaluated and experiments showed that the C-arm geometry can be predicted with a mean 2D reprojection error of 0.5 mm. The interest of 3D augmented uoroscopy is also assessed on a clinical case

Preliminary Study of Rib Articulated Model based on Dynamic Fluoroscopy Images

International audienceWe present in this paper a preliminary study of rib motion tracking during Interventional Radiology (IR) fluoroscopy guided procedures. It consists in providing a physician with moving rib three-dimensional (3D) models projected in the fluoroscopy plane during a treatment. The strategy is to help to quickly recognize the target and the no-go areas i.e. the tumor and the organs to avoid. The method consists in i) elaborating a kinematic model of each rib from a preoperative computerized tomography (CT) scan, ii) processing the on-line fluoroscopy image and iii) optimizing the parameters of the kinematic law such as the transformed 3D rib projected on the medical image plane fit well with the previously processed image. The results show a visually good rib tracking that has been quantitatively validated by showing a periodic motion as well as a good synchronism between ribs

Reconstruction vasculaire à l'aide d'un modèle Markovien 3D

Dans le cadre de la reconstruction 3D du réseau vasculaire à partir d'un ensemble de projections, notre contribution est relative au développement d'un modèle markovien rendant compte des propriétés géométriques et morphologiques des structures vasculaires. L'intérêt de ce modèle est de diminuer le bruit lors de la reconstruction, de rehausser les petits vaisseaux faiblement contrastés et de garantir la précision de la représentation 3D. La minimisation de la fonctionnelle globale d'énergie s'effectue à l'aide d'un algorithme ICM, les paramètres du modèle étant estimés lors de l'étape d'initialisation. Des résultats expérimentaux à partir de données réelles in vivo montrent la pertinence du modèle

Dual-rotation C-arm cone-beam computed tomography to increase low-contrast detection

International audiencePurpose: This paper investigates the capabilities of a dual-rotation C-arm cone-beam computed tomography (CBCT) framework to improve non-contrast-enhanced low-contrast detection for full volume or volume-of-interest (VOI) brain imaging.Method: The idea is to associate two C-arm short-scan rotational acquisitions (spins): one over the full detector field of view (FOV) at low dose, and one collimated to deliver a higher dose to the central densest parts of the head. The angular sampling performed by each spin is allowed to vary in terms of number of views and angular positions. Collimated data is truncated and does not contain measurement of the incoming X-ray intensities in air (air calibration). When targeting full volume reconstruction, the method is intended to act as a virtual bow-tie. When targeting VOI imaging, the method is intended to provide the minimum full detector FOV data that sufficiently corrects for truncation artifacts. A single dedicated iterative algorithm is described that handles all proposed sampling configurations despite truncation and absence of air calibration.Results: Full volume reconstruction of dual-rotation simulations and phantom acquisitions are shown to have increased low-contrast detection for less dose, with respect to a single-rotation acquisition. High CNR values were obtained on 1% inserts of the Catphanmath formula 515 module in 0.94 mm thick slices. Image quality for VOI imaging was preserved from truncation artifacts even with less than 10 non-truncated views, without using the sparsity a priori common to such context.Conclusion: A flexible dual-rotation acquisition and reconstruction framework is proposed that has the potential to improve low-contrast detection in clinical C-arm brain soft-tissue imaging

3D reconstruction from incomplete Fourier spectra: An extrapolation approach

3D reconstruction from an incomplete data set is an ill-posed problem. To overcome this drawback, an approach based on constrained optimization is introduced. This approach provides a powerful mathematical framework for selecting a specific solution from the set of feasible solutions; this is done by minimizing some criteria depending on prior densitometric information. We propose a global optimization scheme using a deterministic relaxation algorithm based on Bregman's algorithm associated with half-quadratic minimization techniques. When used for 3D vascular reconstruction from 2D Digital subtracted Angiography (DSA) data, such an approach allows reconstructing well-contrasted 3D vascular network in comparison with results obtained by using standard algorithms. 1 Introduction In many computer imaging applications, such as medical, astronomical, or geophysical imaging, the measured data result from the transformation of an unknown physical parameter. The recovery of the physical param..

Reconstruction tomographique 2D : une nouvelle méthode de rétro-projection filtrée

National audienceEn reconstruction tomographique 2D, le terme de « rétro-projection filtrée » est ambigu, car les projections sont d’abord filtrées puis rétro-projetées dans le plan image. Si l’inversion des opérations est possible mathématiquement, elle n’est jamais appliquée en pratique. Cet article présente un moyen de calculer la rétro-projection filtrée avec la même précision numérique quel que soit l’ordre des opérations. Une illustration dans le cadre de la reconstruction de régions d’intérêt démontre la versatilité de la méthode

Model-Based Multiscale Detection of 3D Vessels

International audienceno abstrac

Model-Based Multiscale Detection of 3D Vessels

International audienceno abstrac