Didier Saint-Felix

Three-dimensional coronary arteriography.

In this paper we present a new imaging technique for three-dimensional (3-D) X-ray coronary arteriography. The goal is to provide in near to real-time a 3-D representation of the coronary arterial tree, helpful to better understand its topology and locate the possible lesions.The 3-D reconstruction of the coronary arteries is obtained from a set of X-ray conic projections acquired during a rotation of the imaging chain around the patient. Images are taken before and after injection of contrast agent. A subset of mask and opacified images is selected, corresponding to the same phase in the cardiac cycle. These images are subtracted and corrected for geometric distortion. The reconstruction is performed by using a two-step non-parametric detection/estimation method.Due to heart motion and propagation of the contrast agent, the number of available projections is very small. Typically 4 or 6 projections are available if the opacification is stable during 2 or 3 cardiac cycles and when using a biplane acquisition system.High resolution 5123 reconstructions of the coronary arteries from a cadaver heart are presented, with a voxel size of 0.4 mm. The 3-D reconstruction provides a good 3-D representation of the global structure, even with a number of projections as small as 4.

Multiscale cone-beam x-ray reconstruction

We address the problem of reconstructing a three-dimensional volume from a set of two-dimensional X-ray projections. We present a time efficient solution based on a multiscale estimation technique. Estimation is first performed at a coarse resolution. Then the resolution is increased step by step and at each step a new estimation is performed, using an initial value derived from the volume estimated at the preceding level of resolution. The method is illustrated by results obtained on geometric and anatomic phantoms.

3D Reconstruction of High Contrast Objects Using a Multi-scale Detection / Estimation Scheme

Reconstructing a three-dimensional (3D) volume from a set of twodimensional X-ray projections raises theoretical, instrumental and computational difficulties. Focused on high contrast objects, solutions are proposed for the successive steps of a 3D reconstruction procedure, from the raw measurements on an image intensifier up to the reconstruction algorithm based on a multi-scale detection / estimation scheme.

Three-dimensional x-ray angiography: first in-vivo results with a new system

A new system has been designed and built to validate the concept of 3D Computerized Angiography (3D CA). It addresses all the difficulties met from the acquisition of raw data on a patient to the display of the reconstructed volume. The main characteristics of the system and its operating modes are described. Special attention is paid to data processing aspects. The first in vivo results obtained with this system are presented.

A new system for 3D computerized X-ray angiography: First in vivo results

A new system has been designed and built to validate the concept of 3D computerized Χ-ray angiography. It addresses all the difficulties met from the acquisition of raw data on a patient to the display of the reconstructed volume. The first in vivo results obtained with this system are presented.

Three-Dimensional Computerized Angiography

A new technique for 3-D angiography is presented. Its purpose is to provide fully automatic, high-resolution 3-D imaging of blood vessels. The 3-D vascular structure is reconstructed from a set of 2-D X-ray conic projections acquired around the patient, using a time-efficient multi-resolution detection/estimation scheme.

3-D Reconstruction Of High Contrast Objects From Limited Conic X-Ray Projections

We address the problem of reconstructing a 3-D object using a few of its conic projections measured with a 2-D X-ray detector. This problem is ill-posed and prior information must therefore be used to regularize the solution. We propose a non-parametric method based on a detection-estimation scheme that is particulary well-suited to the reconstruction of sparse objects such as 3-D vascular structures. We present results of 3-D reconstruction obtained from both computer simulated and experimentally measured projections.

Quantitative 2-D dual energy imaging: towards 3-D selective reconstruction

We address the problem of applying Dual-Energy techniques to Image-Intensifierbased acquisition systems. We propose a new Dual Energy calibration and combination scheme, which takes into account the spatially non-uniform response of the Image Intensifier. During the calibration step, the coefficients of the combination are locally estimated for a set of uniformly spaced points over the image, and interpolated from these samples for the other points. In the combination step, the selective images are generated using the corresponding polynomia for each pixel. 3D selective reconstruction of bone-only structures is presented as a possible application. Experimental results obtained on anthropomorphic phantoms are discussed.