Towards Interactive Planning of Coil Embolization in Brain Aneurysms

The original publication is available at www.springerlink.comInternational audienceMany vascular pathologies can now be treated in a minimally invasive way thanks to interventional radiology. Instead of open surgery, it allows to reach the lesion of the arteries with therapeutic devices through a catheter. As a particular case, intracranial aneurysms are treated by filling the localized widening of the artery with a set of coils to prevent a rupture due to the weakened arterial wall. Considering the location of the lesion, close to the brain, and its very small size, the procedure requires a combination of careful planning and excellent technical skills. An interactive and reliable simulation, adapted to the patient anatomy, would be an interesting tool for helping the interventional neuroradiologist plan and rehearse a coil embolization procedure. This paper describes an original method to perform interactive simulations of coil embolization and proposes a clinical metric to quantitatively measure how the first coil fills the aneurysm. The simulation relies on an accurate reconstruction of the aneurysm anatomy and a real-time model of the coil for which sliding and friction contacts are taken into account. Simulation results are compared to real embolization procedure and exhibit good adequacy

Unsupervised Polygonal Reconstruction of Noisy Contours by a Discrete Irregular Approach

International audienceIn this paper, we present an original algorithm to build a polygonal reconstruction of noisy digital contours. For this purpose, we first improve an algorithm devoted to the vectorization of discrete irregular isothetic objects. Afterwards we propose to use it to define a reconstruction process of noisy digital contours. More precisely, we use a local noise detector, introduced by Kerautret and Lachaud in IWCIA 2009, that builds a multi-scale representation of the digital contour, which is composed of pixels of various size depending of the local amount of noise. Finally, we compare our approach with previous works, by con- sidering the Hausdorff distance and the error on tangent orientations of the computed line segments to the original perfect contour. Thanks to both synthetic and real noisy objects, we show that our approach has interesting performance, and could be applied in document analysis systems

Optimization schemes for the reversible discrete volume polyhedrization using Marching Cubes simplification

International audienceThe aim of this article is to present a reversible and topologically correct construction of a polyhedron from a binary object. The proposed algorithm is based on a Marching Cubes (MC for short) surface, a digital plane segmentation of the binary object surface and an optimization step to simplify the MC surface using the segmentation information

Multi-scale Analysis of Discrete Contours for Unsupervised Noise Detection

International audienceBlurred segments [Debled06] were introduced in discrete geometry to address possible noise along discrete contours. The noise is not really detected but is rather canceled out by thickening digital straight segments. The thickness is tuned by a user and set globally for the contour, which requires both supervision and non-adaptive contour processing. To overcome this issue, we propose an original strategy to detect locally both the amount of noise and the meaningful scales of each point of a digital contour. Based on the asymptotic properties of maximal segments, it also detects curved and flat parts of the contour. From a given maximal observation scale, the proposed approach does not require any parameter tuning and is easy to implement. We demonstrate its effectiveness on several datasets. Its potential applications are numerous, ranging from geometric estimators to contour reconstruction

Top-Down segmentation of histological images using a digital deformable model

International audienceThis paper presents a straightforward top-down segmentation method based on a contour approach on histological images. Our approach relies on a digital deformable model whose internal energy is based on the minimum length polygon and that uses a greedy algorithm to minimise its energy. Experiments on real histological images of breast cancer yields results as good as that of classical active contours

Algorithms for Fast Digital Straight Segments Union

International audienceGiven two Digital Straight Segments (DSS for short) of known minimal characteristics, we investigate the union of these DSSs: is it still a DSS ? If yes, what are its minimal characteristics ? We show that the problem is actually easy and can be solved in, at worst, logarithmic time using a state-of-the-art algorithm. We moreover propose a new algorithm of logarithmic worst-case complexity based on arithmetical properties. But when the two DSSs are connected, the time complexity of this algorithm is lowered to O(1) and experiments show that it outperforms the state-of-the art one in any case

Variational shape and reflectance estimation under changing light and viewpoints

Fitting parameterized 3D shape and general reflectance models to 2D image data is challenging due to the high dimensionality of the problem. The proposed method combines the capabilities of classical and photometric stereo, allowing for accurate reconstruction of both textured and non-textured surfaces. In particular, we present a variational method implemented as a PDE-driven surface evolution interleaved with reflectance estimation. The surface is represented on an adaptive mesh allowing topological change. To provide the input data, we have designed a capture setup that simultaneously acquires both viewpoint and light variation while minimizing self-shadowing. Our capture method is feasible for real-world application as it requires a moderate amount of input data and processing time. In experiments, models of people and everyday objects were captured from a few dozen images taken with a consumer digital camera. The capture process recovers a photo-consistent model of spatially varying Lambertian and specular reflectance and a highly accurate geometry

Author manuscript, published in "CompIMAGE, Buffalo-Niagara: États-Unis (2010)" Curvature Estimation for Discrete Curves Based on Auto-adaptive Masks of Convolution

Abstract. We propose a method that we call auto-adaptive convolution which extends the classical notion of convolution in pictures analysis to function analysis on a discrete set. We define an averaging kernel which takes into account the local geometry of a discrete shape and adapts itself to the curvature. Its defining property is to be local and to follow a normal law on discrete lines of any slope. We used it together with classical differentiation masks to estimate first and second derivatives and give a curvature estimator of discrete functions.

An Arithmetical Characterization of the Convex Hull of Digital Straight Segments

International audienceIn this paper, we arithmetically describe the convex hull ofa digital straight segment by three recurrence relations. This charac-terization gives new insights into the combinatorial structure of digitalstraight segments of arbitrary length and intercept. It also leads to twoon-line algorithms that computes a part of the convex hull of a givendigital straight segment. They both run in constant space and constanttime per vertex. Due to symmetries, they are enough to reconstructthe whole convex hull. Moreover, these two algorithms provide efficientsolutions to the subsegment problem, which consists in computing theminimal parameters of a segment of a digital straight line of known pa-rameters. Due to its close link to the subsegment problem, this workhelps to understand the effects of length and intercept on segments ofparallel digital straight lines, such as sections of a piece of digital planeor sub-sampled digital straight segments