Dynamite

Clinical Background

Coronary Artery Disease (CAD) is a disease in which plaque appears inside the coronary arteries. These arteries supply enriched oxygen blood to the heart muscle, called the myocardium. Over time, plaque can cause partial or complete blockage of the myocardial blood flow (fig 1). Consequently; patients can experience chest pain or discomfort, sometimes resulting in a heart attack.

Myocardial Perfusion Imaging (MPI) is a reliable tool to diagnose CAD (and other heart diseases). Different imaging modalities are used for MPI within the radiology and nuclear medicine department, including CT, MRI, SPECT, and PET. Current clinical practice guidelines do not indicate a clear validated standard for MPI. An important underlying cause is that the wide range in imaging settings result in limited intra- and inter-modality comparability of patient studies.


Fig. 1 Visualization of Coronary Artery Disease (CAD). Blockage of the coronary arteries is caused by plaque buildup (Source: http://cts.usc.edu/hpg-coronaryarterydisease.html)

Goal

Our objective is to develop a validated standard for MPI by means of developing an anthropomorphic dynamic myocardial perfusion phantom suited for multi-modality imaging comparison. This project is an enduring research collaboration between the University of Twente, the University Medical Center Groningen, the industry VDL Wientjes, and the University of Muenster, Germany.

About Dynamite

The innovative character of Dynamite is that we aim to develop a more realistic myocardial perfusion phantom compared to existing static heart phantoms. At this moment, our second prototype is completed (figure 2a). A programmable pulsatile pump regulates ‘blood’ flow through the heart. Its perfusion element is reconstructed with a hemodialysis filter, which we use to simulate exchange of fluid between the coronary arteries and the myocardial compartment. An additional pump is connected to the phantom to simulate heart beating.


fig. 2a 2nd prototype      fig. 2b 1st phantom test in a CT-scanner

Recently, we tested our prototype for the first time in the clinic (figure 2b). At first, we injected a contrast agent into the ‘blood’ flow towards the heart, followed by a dynamic CT-scan (movie 1). Afterwards we derived time-intensity curves from different regions of interest (ROIs). Figure 3 shows a steep rise in intensity quickly after injection of the contrast agent, followed by a drop as the contrast agent gets washed out. The distribution of contrast agent is similar throughout the entire myocardial compartment. So, in this case the CT scan of the heart indicates no perfusion defect. Our first experiment was very successful!


fig. 3 Time-intensity curve for two Regions of Interest (ROIs) inside the heart phantom

Next steps in the project include:

- Optimize the prototype;
- Prepare, perform and analyze quantitative perfusion experiments on CT;
- If successful, test the phantom in other imaging modalities (MRI, SPECT and PET);
- Implement realistic perfusion defects;
- Etc.

We are always looking for motivated students (BSc or MSc) from different study backgrounds. Are you interested in this topic? And do you like to be part of a multi-disciplinary team? If so, just send an email to m.e.kamphuis@utwente.nl and we will discuss the possibilities for an assignment!

Project lead

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prof.dr. R.H.J.A. Slart

Participants

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dr. Marcel Greuter
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Marije Kamphuis MSc
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prof.dr.ir. Kees Slump