Simulation Model of Microsphere Distribution for Selective Internal Radiation Therapy Agrees With Observations
Jonas Högberg1, Magnus Rizell2, Ragnar Hultborn3
1Department of Radiation Physics, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Summary
This study modeled microsphere distribution in liver arteries after Yttrium-90 radioembolization. Findings show larger microsphere clusters in areas with higher concentrations, emphasizing the importance of hepatic artery tree structure in distribution estimates.
Area of Science:
- Radiology and Nuclear Medicine
- Biomedical Engineering
- Medical Imaging
Background:
- Radioembolization with Yttrium-90 (90Y) resin spheres is a treatment for liver tumors.
- Accurate prediction of microsphere distribution is crucial for treatment efficacy and minimizing off-target effects.
- Understanding microsphere deposition patterns within the hepatic arterial tree is essential for optimizing treatment planning.
Purpose of the Study:
- To analyze microsphere distribution in liver biopsy samples from a patient treated with 90Y-labeled resin spheres.
- To characterize microsphere distribution within the hepatic artery tree.
- To develop and evaluate a novel dichotomous bifurcation model for simulating microsphere deposits.
Main Methods:
- A virtual model of the hepatic artery tree was constructed with 20 branching nodes.
- Three parameters were optimized for model-patient concordance: artery coefficient of variation (ACV), hepatic tree distribution volume (HDV), and artery diameter reduction (ADR).
- The model was validated against activity concentrations measured in 84 liver biopsies, with microsphere distribution analyzed via light microscopy.
Main Results:
- Microsphere distribution varied, with single spheres/small clusters in terminal arterioles and large clusters (up to 450 spheres) in larger arterioles.
- Optimized parameters (ACV, HDV, ADR) differed across varying microsphere concentrations (4.6, 14, and 28 microspheres/mg).
- Higher microsphere concentrations correlated with larger and more frequent microsphere clusters.
Conclusions:
- Simulations and measurements demonstrate that microsphere clusters are larger and more prevalent in regions with higher concentrations.
- The spatial architecture of the hepatic artery tree significantly influences microsphere distribution patterns.
- The developed dichotomous bifurcation model provides a valuable tool for simulating and understanding microsphere deposition in radioembolization.
