Author: Roger Eric Goldman, Adrianna Imani Johnson Carter, Talia Marx, Brahim Mehadji, Emilie Roncali, Catherine T. Vu 👨🔬
Affiliation: UC Davis, Department of Radiology, UC Davis Health 🌍
Purpose:
Accurate estimation of the Lung Shunt Fraction (LSF) is critical for yttrium-90 (90Y) radioembolization treatment planning to minimize risks of excessive lung irradiation due to arterio-venous shunting in the liver. While standard practice involves 99mTc macroaggregated albumin (99mTc-MAA) imaging, this adds complexity, risk, and financial burden. This study explores the feasibility of using Contrast-Enhanced Computed Tomography (CECT) as a non-invasive alternative for LSF prediction.
Methods:
This retrospective study included 30 liver cancer patients who underwent both 4-phase CECT and 99mTc-MAA imaging before 90Y radioembolization. A novel metric was developed based on hypervascular volumes derived from the subtraction of the portal phase from the arterial phase of CECT. These were then normalized by the perfused volume (generally the treated lobe or segment). Correlations between these metrics and LSF values obtained from 99mTc-MAA planar gamma imaging were analyzed.
Results:
The study revealed a strong correlation (R²=0.95) between the hypervascular-to-perfused volume ratio derived from CECT and the LSF obtained via standard 99mTc-MAA planar imaging. The predictive power of the hypervascular-to-perfused volume ratio demonstrated a 1-sigma uncertainty of 3%.
Conclusion: CECT-based LSF estimation shows significant promise as a non-invasive alternative to 99mTc-MAA imaging for 90Y radioembolization treatment planning. By leveraging arterial and portal phase differences, this approach eliminates the need for nuclear imaging while maintaining accuracy. Validation through prospective studies with larger patient cohorts is needed to confirm its clinical utility and safety.