Fusion of imaging parameters

Fusion of imaging parameters for prediction of plaque rupture in human coronary arteries

Summary

Cardiovascular disease, and more specifically an acute myocardial infarction, is the main cause of sudden death in the Netherlands. Acute myocardial infarctions are mainly triggered by rupture of so-called vulnerable plaques in the coronary arteries. These plaques are often referred to as ‘silent killers’: although they are prone to rupture, vulnerable plaques often do not cause symptoms and therefore they remain unnoticed by the patient until they induce an often fatal event. The detection -and subsequent treatment- of these rupture prone vulnerable plaques is therefore of eminent importance and a very active research field in cardiology. In this project, we will develop new image-based tools to improve both identification of rupture prone plaques and risk prediction.

Vulnerable plaques are advanced atherosclerotic plaques and they are characterized by the presence of a lipid pool covered by a thin fibrous cap. Rupture of the fibrous cap will expose the content of the lipid pool to the blood, which leads to thrombus formation and subsequent occlusion of the coronary artery. Wall shear stress (WSS) – the frictional force of the blood at the vessel wall- plays an important role in the development and progress of atherosclerotic plaques. It was recently shown that high WSS initiates various processes that lead to local weakening of the cap. Clinical studies confirm that plaque rupture often occurs in the upstream region of a plaque which is exposed to elevated WSS levels. Although WSS seems to be a relevant parameter in predicting plaque rupture, it is unlikely that elevated WSS alone is enough to identify rupture prone plaques. The combination of elevated WSS and a well known geometrical risk factor -cap thickness- is a potential candidate to predict the location of plaque rupture. The aim of the current proposal is to develop tools to determine new diagnostic parameters to identify rupture prone plaques in a clinical setting by the fusion of WSS and cap thickness data.

WSS will be calculated by performing computational fluid dynamics (CFD) calculations based on 3D reconstruction of the lumen of the coronary artery. The 3D reconstruction will be derived from biplane angiography by improvement of the current 3D coronary reconstruction software. Combined with new models to estimate flow data, WSS computations in patient specific coronary artery geometries will be performed. Geometric information about the thickness of the cap will be derived from optical coherence tomography (OCT) data using image processing tools which will be developed in this project. In a final step, a software tool will be developed to combine WSS and cap thickness information. The software tool will be optimised to yield a prototype for online assessment of WSS and cap thickness in the Catheterization Laboratory to support cardiologists in treatment strategies.

Utilization Summary

Acute myocardial infarctions often occur before patients develop symptoms. The underlying cause of these often fatal events is rupture of vulnerable plaque. Identification of rupture prone plaques is therefore of eminent importance. We identified two potentially important image-based risk factors –WSS and cap thickness- to improve the prediction of plaque rupture. To determine and quantify these parameters, the expertise of two academic groups is essential: the Biomedical Engineering Department has an extensive experience in patient-based WSS computations, and the Biomedical Imaging Group Rotterdam (BIGR) has large experience in (cardiovascular) image analysis. Together with industrial partners and clinicians, tools will be developed to quantify the WSS and cap thickness and translate these tools into a software prototype suitable for the clinical arena.

For the translation of the developed tools into commercially available software, Pie Medical Imaging is the main industrial partner in this project. Pie Medical Imaging is dedicated to the development and sales of quantitative analysis software to support medical professionals with the diagnostic process and applied treatment and to facilitate research to study the efficacy of modern cardiovascular interventions. The result of this project – new diagnostic parameters by online shear stress assessment and determination of cap thickness makes it possible to provide important information about plaque vulnerability to the cardiologist. Choosing image modalities which are accessible in the cardiac catheterization laboratory –angiography and OCT – will make utilization of the proposed research extremely feasibly. Pie Medical Imaging shall develop multiple prototypes in close collaboration with industrial and clinical partners to receive valuable feedback in an early phase providing the possibility to evaluate and validate the functionality and adaptation success. For successful translation of the tools into the clinical arena, the input of Cardialysis is very important. Cardialysis conducts large multi center trials for pharmaceutical companies and they have lively interest in novel (imaging) biomarkers. The results of this project will provide them with new (surrogate) endpoints in their studies to investigate the effect of new drugs, and hence they are very interested in image based plaque parameters as developed in this study. The optimization of the WSS computation will be performed in close collaboration with SEPRA. SEPRA is an engineering consultancy company that develops and applies finite element software for various engineering applications. SEPRA is involved in various STW projects related to cardiovascular fluid dynamics, and the current project will potentially provide the company with new modules for image-based cardiovascular modeling of coronary blood flow.

The project will greatly benefit from the continuous input from these industrial partners with a proven track record in transferring high-technology methods to commercial products in a clinical setting.

Project Team:

  • dr.ir. F. Gijsen, Biomedical Engineering, ErasmusMC, f.gijsen@erasmusmc.nl - Project Leader

Project 1: shear stress in human coronary arteries

Project 2: cap thickness from OCT