31356 Using CFD for the design and evaluation of medical catheters for transarterial liver cancer treatments
Begeleider(s): Tim Bomberna
Richtingen: Master of Science in Biomedical Engineering, International Master of Science in Biomedical Engineering

Probleemstelling:

CURRENT SHORTCOMINGS: SUBOPTIMAL TREATMENTS FOR LIVER CANCER 

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, ranking fourth in mortality worldwide. At its intermediate, unresectable stage, HCC can be treated by transarterial chemoembolization (TACE) or radioembolization (TARE). During these therapies, catheters are retrogradely advanced through the femoral artery to the hepatic arteries (Fig. 1, panels 1&2), where embolizing microspheres are locally injected to selectively damage tumor tissue (Fig. 1, panel 3). The overall goal is to steer the damaging microspheres towards the tumor tissue to (i) maximize drug delivery to the tumor, and (ii) limit the amount of toxicity delivered to healthy tissue. However, the execution of these procedures depends on the implementation of several clinically variable parameters: the axial injection location (e.g. close to the tumor or more upstream), the catheter type (e.g. fixed vs variable tip orientation), the microsphere type (different sizes and densities), etc. Since some patients respond well to the treatment and others do not, it is currently unclear to which extent these treatment heterogeneities contribute to suboptimal outcomes in some patients. 

Figure 1. The workflow for transarterial therapies (TACE, TARE). A catheter is inserted in the femoral artery and navigated towards the liver. Damaging microspheres are injected as close as possible to the tumor to maximize the target-specificity of the treatment.

RESEARCH GOAL: USING COMPUTER MODELS TO EVALUATE MEDICAL DEVICES

Therefore, computational fluid dynamics (CFD) modelling has been applied to elucidate the role of these clinical parameters. For example, CFD simulations of blood and microparticle flow in the hepatic arteries have already shown that the injection location and timing can have a large impact on the downstream particle distribution. Additionally, CFD simulations can be used to evaluate the impact of using different catheter types (see Fig. 2 for an example). As of now, multiple catheter types are commercially available, but the direct impact of these different designs is currently unclear. Relevantly, using computer models to compare different medical devices is already very common in cardiology, but not yet in the liver. Therefore, this thesis will focus on developing computer models of different catheter types in the hepatic arteries, and evaluating their impact on the blood flow and microparticle distribution. 

Figure 2. Example of comparing a straight standard microcatheter and a microcatheter with expanded tip in a virtual model of the blood flow. 

 


Doelstelling:

The aim of this Master thesis is to develop and validate a patient-specific computer model to evaluate the designs of microcatheters for transarterial drug delivery in the liver. 

The workflow of this thesis can be divided in several succinct steps.

       (i) Literature study, in which the student(s) will explore the problem setting and identify relevant research questions.

       (ii) Segmentation and meshing of the arterial network of the liver. Practically, imaging data (e.g. CT, MRI) of the liver vasculature of 1-2 patients will be used to create 3D models for simulation geometries (Figure 2) in Mimics (Materialise, Belgium). The meshes (i.e. subdivision of the geometry in small elements) can be made in Fluent Meshing (Ansys, USA). 

       (iii) CFD modelling. From a modelling point of view, this transport problem can be translated in a dispersion of discrete phase particles (drug carriers) in a continuous fluid phase (blood). This will be done in Fluent (Ansys, USA). This CFD model can help to evalute the near-tip blood flow patterns (see Fig. 2), the pressure drop over the device, the impact on the microparticle distribution, etc. 

        (iv) Validation. Validation can be done in two stages using an available experimental set-up consisting of a patient-specific 3D-print of the hepatic arteries in which fluid flow and microparticle transport is mimicked (see Fig. 3). First, the catheter can be inserted and colored dye can be injected to visualize the streamline patterns. This can be compared to results from the CFD model. Second, microparticles can be injected and the downstream particle distribution can be calculated. Again, this can be compared with the CFD model. 

Figure 3. Experimental set-up containing a 3D-print of the hepatic arteries. Microparticles are injected in the proper hepatic artery and the flow and microparticles are collected in the reservoir to be weighed later.