Post-Treatment PET/CT Dosimetry to Predict Contralateral Lobe Hypertrophy After Transarterial Radioembolization for...

Image-based dosimetry in transarterial radioembolization (TARE) has been proposed for the prediction of contralateral lobe hypertrophy as well as tumor response. This study aimed to evaluate the predictive value of post-treatment ⁹⁰Y PET/CT voxel-based dosimetry for post-TARE liver hypertrophy in treatment-naïve patients with hepatocellular carcinoma (HCC).

This retrospective single-center study included 40 treatment-naïve patients with right lobar HCC (age, 66.4 ± 12.5 years; male:female, 29:11) who underwent TARE with ⁹⁰Y-labeled glass microspheres. Voxel-based absorbed dose maps were generated from ⁹⁰Y PET/CT performed 16-24 hours post-treatment; dose histograms were obtained for the whole liver, right lobe (RL), and non-tumor RL (NRL). Mean absorbed dose and volume proportion receiving ≥50 Gy (P₅₀) and ≥100 Gy (P₁₀₀) for each region were calculated. All patients underwent follow-up CT-2-4 months after treatment, and the percentage increase in left lobe (LL) volume was measured using CT volumetry. The efficacy of dosimetric parameters and conventional clinical factors in predicting LL hypertrophy was analyzed using Spearman's correlation and multivariable regression.

The median LL volume increase was 12.7% (interquartile range, 5.7%-28.1%). The mean absorbed dose (ρ = 0.662, P < 0.001) and P₅₀ (ρ = 0.672, P < 0.001) of NRL showed the strongest correlations with LL hypertrophy. In multivariable regression integrating clinical factors, the mean NRL dose was the only independent dosimetric predictor (R² = 0.556, P < 0.001); platelet count also remained independently predictive (R² = 0.221, P = 0.003). The relationship between NRL dose and LL hypertrophy was markedly stronger in patients with preserved platelet counts (platelet ≥130 × 10³/µL; ρ = 0.847; P < 0.001) than in those with decreased platelet counts (ρ = 0.429; P = 0.129).

Post-TARE ⁹⁰Y PET/CT dosimetry, particularly in combination with platelet count, is an effective approach to predict contralateral hypertrophy in treatment-naïve patients with HCC. Further studies with larger prospective cohorts are required to validate these predictive strategies.