Optimizing ⁹⁰Y Particle Density Improves Outcomes After Radioembolization

Area of Science:

• Interventional Radiology
• Nuclear Medicine
• Oncology

Background:

• Lobar radioembolization uses microspheres to deliver radiation directly to liver tumors.
• Particle density influences radiation dose distribution and treatment efficacy.
• Understanding the relationship between particle density, dose, and outcomes is crucial for optimizing therapy.

Purpose of the Study:

• To investigate the impact of particle density on dose distribution and patient outcomes in lobar radioembolization.
• To compare outcomes between glass and resin microspheres based on particle density.

Main Methods:

• Retrospective study of 114 matched patients treated with glass versus resin microspheres.
• Analysis of tumor and liver particle density (particles/cm³), and radiation dose (Gy).
• Utilized 99mTc-MAA SPECT/CT and 90Y bremsstrahlung SPECT/CT for dose assessment and microdosimetry simulations to calculate cold spot doses.

Main Results:

• Increased particle delivery led to more uniform 90Y doses, reducing differences between tumor and liver doses.
• Optimal particle density, tailored to tumor vascularity (hypervascular vs. less vascular), improved local progression-free survival (LPFS).
• Optimized particle density significantly improved overall survival (11.5 vs. 6.8 months) and microdosimetry predictions compared to conventional dosimetry.

Conclusions:

• Particle density can be adjusted based on tumor vascularity to maximize tumor dose and minimize liver dose.
• Optimizing particle density is a key factor in improving LPFS and overall survival in radioembolization.
• Microdosimetry offers superior prediction of treatment outcomes compared to conventional dosimetry.