David Rotger

Late Stent Recoil of the Bioabsorbable Everolimus-Eluting Coronary Stent and its Relationship With Plaque Morphology

OBJECTIVES This study sought to evaluate late recoil of a novel bioabsorbable everolimus-eluting coronary stent (BVS), which is composed of a poly-L-lactic acid backbone, coated with a bioabsorbable polymer containing everolimus. BACKGROUND Little is known about the mechanical behavior of bioabsorbable polymer stents after deployment in diseased human coronary arteries. METHODS The study population consisted of 16 patients, who were treated with elective BVS implantation for single de novo native coronary artery lesions and were followed at 6 months. All patients underwent an intravascular ultrasound examination at post-procedure and follow-up. A total of 484 paired cross-sectional areas (CSAs) were acquired and analyzed. Late absolute stent recoil was defined as stent area at post-procedure (X) - stent area at follow-up (Y). Late percent stent recoil was defined as (X - Y)/X x 100. In each CSA, plaque morphology was assessed qualitatively and classified as calcific, fibronecrotic, or fibrocellular plaque. RESULTS Late absolute and percent recoil of the BVS was 0.65 +/- 1.71 mm(2) (95% confidence interval [CI]: 0.49 to 0.80 mm(2)) and 7.60 +/- 23.3% (95% CI: 5.52% to 9.68%). Calcified plaques resulted in significantly less late recoil (0.20 +/- 1.54 mm(2) and 1.97 +/- 22.2%) than fibronecrotic plaques (1.03 +/- 2.12 mm(2) and 12.4 +/- 28.0%, p = 0.001 and p = 0.001, respectively) or fibrocellular plaque (0.74 +/- 1.48 mm(2) and 8.90 +/- 19.8%, p = 0.001 and p = 0.001, respectively). CONCLUSIONS The BVS shrank in size during the follow-up period. The lesion morphology of stented segments might affect the degree of late recoil of the BVS. (ABSORB Everolimus Eluting Coronary Stent System First in Man Clinical Investigation; NCT00300131).

Automatic Detection of Bioabsorbable Coronary Stents in IVUS Images Using a Cascade of Classifiers

Bioabsorbable drug-eluting coronary stents present a very promising improvement to the common metallic ones solving some of the most important problems of stent implantation: the late restenosis. These stents made of poly-L-lactic acid cause a very subtle acoustic shadow (compared to the metallic ones) making difficult the automatic detection and measurements in images. In this paper, we propose a novel approach based on a cascade of GentleBoost classifiers to detect the stent struts using structural features to code the information of the different subregions of the struts. A stochastic gradient descent method is applied to optimize the overall performance of the detector. Validation results of struts detection are very encouraging with an average F -measure of 81%.

Internal and External Coronary Vessel Images Registration

The growing appreciation of the pathophysiological and prognostic importance of arterial morphology has led to the realization that angiograms are inherently limited in defining the distribution and extension of coronary wall disease. By Intravascular Ultrasound images physicians have a picture of the composition of vessel in detail. However, observing an intravascular ultrasound stack of images, it is difficult to figure out the image position and extension with regard to the vessel parts and ramifications, and misclassification or misdiagnosis of lesions is possible. The objective of this work is to develop a computer vision technique to fuse the information from angiograms and intravascular ultrasound images defining the correspondence of every ultrasound image with a corresponding point of the vessel in the angiograms.

Blood detection in IVUS images for 3D volume of lumen changes measurement due to different drugs administration

Lumen volume variations is of great interest by the physicians given it reduces the probability of infarction as it increases. In this paper we present a fast and efficient method to detect the lumen borders in longitudinal cuts of IVUS sequences using an AdaBoost classifier trained with several local features assuring their stability. We propose a criterion for feature selection based on stability leave-one-out cross validation. Results on the segmentation of 18 IVUS pullbacks show that the proposed procedure is fast and robust leading to 90% of time reduction with the same characterization performance.

Building and registering parameterized 3D models of vessel trees for visualization during intervention

In this paper, we address the problem of multimodal registration of coronary vessels by developing a 3D parametrical model of vessel trees from computer tomography data and registering it to angiography images during intervention. Thus, the interventionist takes profit from 3D data otherwise only available before the intervention. This facilitates orientation in ambiguous radiographs, interactive visualization of all vessel structures to estimate their mutual position and navigation within the vessel system and ultimately reduces the radiation the patient and the physicians are exposed to. The model is build by exploring the branching vessel tree starting from a single position and successively expanding through the vessels guided by a local deformable surface. The result is a tree of cylindrical segments each adapted to the vessel walls that is registered to angiography images in a fast and robust way. Validation on 8 patients confirms the robustness of our method.

Integration of multiple sensor modalities in active vessel cardiology workstation

Active vessel is a new multimedia workstation which enables the visualization, acquisition and handling of different medical image modalities on- and offline for cardiology purposes. It implements DICOM v3.0 decompression and browsing, video acquisition, reproduction and storage for intravascular ultrasound (IVUS) and angiogram analysis. A distinctive implementation feature is the automatic catheter segmentation in angiography images. Another distinctive feature is the interactive mode of model correction via mouse dragging. A third and novel technical solution of the catheter path reconstruction is the integration with a magneto-sensitive micro-device inside the catheter for faster and safer minimal invasive surgical intervention. The paper gives the overview of the entire system, its basic new functionalities and the proposed technical solution of integration of four (instead of three) sensor modalities in cardiovascular practice.

Multimodal Data Fusion for Intelligent Cardiovascular Diagnosis and Treatment in the Active Vessel Medical Workstation

ActiveVessel is a new multimedia workstation that enables the visualization, acquisition, and handling of different medical image modalities onand off-line for cardiology purposes. The workstation implements image decompression and browsing, video acquisition, reproduction, and storage for intravascular ultrasound (IVUS) and angiogram (X-ray) analysis. A distinctive implementation feature is the automatic image reconstruction with intensive use of 2D and 3D deformable models (snakes). The interactive interface allows the user to ‘correct’ deviations of catheter path reconstruction. An important characteristic feature of ActiveVessel is the interactive mode of model correction via mouse dragging. A novel technical solution for catheter path reconstruction is the integration with a magneto-sensitive micro-device (MSMD) inside the catheter/ vessel for faster and safer minimal invasive surgical intervention. This paper gives the overview of the entire system, its basic new functionalities, and the proposed technical solution of integration of four sensor modalities in cardiovascular practice.

An interface system based on multimodal principle for cardiological diagnosis assistance

A pilot interface system is developed for computer-aided diagnostic and interventional assistance of cardiologists based on clinical trials. The system includes optimized methods for processing and presentation of cardiological knowledge and data. The multimodal principle of the interface is based on know-how tests of a new magnetic microsensor for detection of catheter navigation in images from angiograms and intra-vascular ultrasound and on new investigations of the principle of operation of the electrocardiograph. The user interface includes interactive access to the clinical database and a cognitive approach to disease visualization.

Advanced Visualization of 3D Data of Intravascular Ultrasound Images

Intravascular ultrasound images (IVUS) have allowed deepening in the knowledge of the true extension of the coronary vessel illness. Today, vessel diagnosis is limited to observation and measurements in the IVUS planes. For a bigger accuracy, 3D visualization is necessary to allow estimating the extension, localization and severity of the pathology. We develop tools for interactive 3D visualization to extend the views to any sailing angle through the cube of IVUS data. As a result, physicians are allowed to inspect and get 3D measurements about the vessel pathology from IVUS images.