Onno Wink

Fast delineation and visualization of vessels in 3-D angiographic images

A method is presented which aids the clinician in obtaining quantitative measures and a three-dimensional (3-D) representation of vessels from 3-D angiographic data with a minimum of user interaction. Based on two user defined starting points, an iterative procedure tracks the central vessel axis. During the tracking process, the minimum diameter and a surface rendering of the vessels are computed, allowing for interactive inspection of the vasculature. Applications of the method to CTA, contrast enhanced (CE)-MRA and phase contrast (PC)-MRA images of the abdomen are shown. In all applications, a long stretch of vessels with varying width is tracked, delineated, and visualized, in less than 10 s on a standard clinical workstation.

Multiscale vessel tracking

A method is presented that uses a vectorial multiscale feature image for wave front propagation between two or more user defined points to retrieve the central axis of tubular objects in digital images. Its implicit scale selection mechanism makes the method more robust to overlap and to the presence of adjacent structures than conventional techniques that propagate a wave front over a scalar image representing the maximum of a range of filters. The method is shown to retain its potential to cope with severe stenoses or imaging artifacts and objects with varying widths in simulated and actual two-dimensional angiographic images.

Rapid Prototyping A New Tool in Understanding and Treating Structural Heart Disease

As the appreciation of structural heart disease in children and adults has increased and as catheter-based closure procedures are now being performed in clinical practice, cardiovascular physicians have multiple compelling new reasons to better understand cardiac anatomic and spatial relationships. Current 2-dimensional imaging techniques remain limited both in their ability to represent the complex 3-dimensional relationships present in structural heart disease and in their capacity to adequately facilitate often complex corrective procedures. This review discusses the cardiovascular applications of rapid prototyping, a new technology that may not only play a significant role in the planning of catheter-based interventions but also may serve as a valuable educational tool to enhance the medical community’s understanding of the many forms of structural heart disease.

Randomized study of the safety and clinical utility of rotational angiography versus standard angiography in the diagnosis of coronary artery disease.

This study evaluates the safety and clinical utility of rotational angiography in the diagnosis of coronary artery disease. High‐speed rotational angiography is a newly available angiographic modality that gives a dynamic multiple‐angle perspective of the coronary tree during a single contrast injection. We prospectively randomized 56 patients referred for diagnostic coronary angiography to either standard or rotational angiography. Contrast and radiation utilization were compared between the two groups. The number of additional cine acquisitions needed was used to determine adequacy of the diagnostic study protocol. Rotational angiography was successfully completed in all subjects. There was a 33% reduction in contrast utilization in the rotational group as compared to the standard group (35.6 ± 12.6 vs. 52.8 ± 10.7 ml, respectively; P < 0.0001). Additionally, there was a 28% reduction in total radiation exposure in the rotational group as compared to the standard group (39.0 ± 18.5 vs. 53.9 ± 23.4 Gycm2, respectively; P = 0.01). Total whole‐body radiation exposure to the primary operator was 144 mrem with rotational angiography and 170 mrem with standard angiography. Procedure time tended to be shorter for rotational angiography (353.9 ± 146.7 vs. 396.8 ± 165.8 s; P = 0.3). Rotational coronary angiography can be rapidly performed in any patient and provides a significant reduction in contrast and radiation utilization while at the same time providing adequate angiographic data to complement or replace standard coronary angiography in the evaluation of coronary artery disease. Catheter Cardiovasc Interv 2004;62:167–174.

3D MRA coronary axis determination using a minimum cost path approach

A method is introduced to automatically find the coronary axis based on two or more user‐defined points, even in the presence of a severe stenosis. The coronary axis is determined by finding a minimum cost path (MCP) in a feature image in which the tubular‐like structures are enhanced. The results of the proposed method were compared with manually drawn central axes to estimate the accuracy. In 32 3D TFE‐EPI acquisitions of patients and volunteers, 14 right coronary arteries (RCAs), 15 left anterior descending arteries (LADs), and eight left circumflex arteries (LCXs) were manually tracked twice by two operators to determine a reference axis and to assess the inter‐ and intra‐user variability. On average, the maximum distance to the reference axis, based on only two user‐defined points, is less than 1.5 mm; the average distance is around 0.65 mm, which is less than the average in‐plane resolution. The results of the method are comparable to those of the manual operators. Magn Reson Med 47:1169–1175, 2002.

Minimum cost path determination using a simple heuristic function

Describes the use of heuristics in the determination of a minimum cost path between two points in digital images. The application of four different search methods when applied in two and three dimensional digital images is presented and evaluated. Experiments show that the number of nodes that are being addressed in the search process strongly depends on the discriminative power of the feature used. Furthermore it is shown that for a specific application, the use of a simple heuristic function leads to a considerable reduction in the number of evaluated nodes as compared with the traditional unidirectional approach.

Initial clinical experience of selective coronary angiography using one prolonged injection and a 180° rotational trajectory

Evaluate the safety of prolonged coronary injections during a rotational acquisition covering 180°.

Rotational angiography (RA) and three-dimensional imaging (3-DRA): an available clinical tool

Being able to accurately choose an optimal view for stent positioning, non foreshortened length and to avoid side branches is imperative during therapeutic procedures. Traditional imaging limitations may include the selection of an incorrectly sized stent, inaccurate placement, and/or the need for additional stents. With the use of newer acquisition techniques and three-dimensional (3-D) modeling/reconstructions this can be minimized. We present a case in which with the assistance of 3-D and its computer derived optimal view, and optimal length, a significant amount of vessel foreshortening was eliminated therefore improving the procedural outcome.

Safety and efficacy of dual-axis rotational coronary angiography vs. standard coronary angiography.

Objective: To determine the safety and efficacy of dual‐axis rotational coronary angiography (DARCA) by directly comparing it to standard coronary angiography (SA). Background: Standard coronary angiography (SA) requires numerous fixed static images of the coronary tree and has multiple well‐documented limitations. Dual‐axis rotational coronary angiography (DARCA) is a new rotational acquisition technique that entails simultaneous LAO/RAO and cranial/caudal gantry movement. This technological advancement obtains numerous unique images of the left or right coronary tree with a single coronary injection. We sought to assess the safety and efficacy of DARCA as well as determine DARCAs adequacy for CAD screening and assessment. Methods: Thirty patients underwent SA following by DARCA. Contrast volume, radiation dose (DAP) and procedural time were recorded for each method to assess safety. For DARCA acquisitions, blood pressure (BP), heart rate (HR), symptoms and any arrhythmias were recorded. All angiograms were reviewed for CAD screening adequacy by two independent invasive cardiologists. Results: Compared to SA, use of DARCA was associated with a 51% reduction in contrast, 35% less radiation exposure, and 18% shorter procedural time. Both independent reviewers noted DARCA to be at least equivalent to SA with respect to the ability to screen for CAD. Conclusion: DARCA represents a new angiographic technique which is equivalent in terms of image quality and is associated with less contrast use, radiation exposure, and procedural time than SA.

Vessel Axis Determination Using Wave Front Propagation Analysis

A method is presented that aims at finding the central vessel axis in two and three dimensional angiographic images based on a single user defined point. After the vessels in the image are enhanced using a special purpose filter, the operator is asked to point out the vessel of interest. Subsequently, a wave front propagation is started based on the response of the filter. By analyzing the evolution of the wave front, points are retrieved that are very likely to be part of the vessel of interest. These points can either be combined to form a connected structure or to retrieve the minimum cost path to the user defined point. In this paper examples of this approach are given that illustrate the performance of this method in different types of images and in situations where there is no or hardly any image evidence of the vessel at hand.