A Hybrid Particle-Flow CFD Modeling Approach in Truncated Hepatic Arterial Trees for Liver Radioembolization: A Patient-specific Case Study

Tim Bomberna; Saar Vermijs; Maryse Lejoly; Chris Verslype; Lawrence Bonne; Geert Maleux; Charlotte Debbaut

doi:10.3389/fbioe.2022.914979

A Hybrid Particle-Flow CFD Modeling Approach in Truncated Hepatic Arterial Trees for Liver Radioembolization: A Patient-specific Case Study

Front Bioeng Biotechnol. 2022 May 30:10:914979. doi: 10.3389/fbioe.2022.914979. eCollection 2022.

Authors

Tim Bomberna^{1

2}, Saar Vermijs^{1

2}, Maryse Lejoly³, Chris Verslype⁴, Lawrence Bonne⁵, Geert Maleux^{5

6}, Charlotte Debbaut^{1

2}

Affiliations

¹ IBiTech-Biommeda, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.
² Cancer Research Institute Ghent, Ghent University, Ghent, Belgium.
³ Department of Radiology and Medical Imaging, Ghent University Hospital and Ghent University, Ghent, Belgium.
⁴ Department of Clinical Digestive Oncology, University Hospitals Leuven, Leuven, Belgium.
⁵ Department of Radiology, University Hospitals Leuven, Leuven, Belgium.
⁶ Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.

Abstract

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer. At its intermediate, unresectable stage, HCC is typically treated by local injection of embolizing microspheres in the hepatic arteries to selectively damage tumor tissue. Interestingly, computational fluid dynamics (CFD) has been applied increasingly to elucidate the impact of clinically variable parameters, such as injection location, on the downstream particle distribution. This study aims to reduce the computational cost of such CFD approaches by introducing a novel truncation algorithm to simplify hepatic arterial trees, and a hybrid particle-flow modeling approach which only models particles in the first few bifurcations. A patient-specific hepatic arterial geometry was pruned at three different levels, resulting in three trees: Geometry 1 (48 outlets), Geometry 2 (38 outlets), and Geometry 3 (17 outlets). In each geometry, 1 planar injection and 3 catheter injections (each with different tip locations) were performed. For the truncated geometries, it was assumed that, downstream of the truncated outlets, particles distributed themselves proportional to the blood flow. This allowed to compare the particle distribution in all 48 "outlets" for each geometry. For the planar injections, the median difference in outlet-specific particle distribution between Geometry 1 and 3 was 0.21%; while the median difference between outlet-specific flow and particle distribution in Geometry 1 was 0.40%. Comparing catheter injections, the maximum median difference in particle distribution between Geometry 1 and 3 was 0.24%, while the maximum median difference between particle and flow distribution was 0.62%. The results suggest that the hepatic arterial tree might be reliably truncated to estimate the particle distribution in the full-complexity tree. In the resulting hybrid particle-flow model, explicit particle modeling was only deemed necessary in the first few bifurcations of the arterial tree. Interestingly, using flow distribution as a surrogate for particle distribution in the entire tree was considerably less accurate than using the hybrid model, although the difference was much higher for catheter injections than for planar injections. Future work should focus on replicating and experimentally validating these results in more patient-specific geometries.

Keywords: computational fluid dynamics; drug delivery & targeting; hepatocellular carcinoma; in silico medicine; liver radioembolization; pretreatment planning; virtual twins.