Measure of ⁹⁰Y-glass microspheres residue post-TARE using PET/CT and potential impact on tumor absorbed dose in comparison ^99mTc-MAA SPECT/CT dosimetry

Transarterial radio-embolization (TARE) became a routine procedure for non-resectable liver tumor mainly hepatocellular carcinoma (HCC). Personalized dosimetry to the index lesion increased tumor response rate. However, there is no requirement to measure the precise activity injected during TARE. We measured ⁹⁰Y-glass microspheres residue (⁹⁰Y-Res) in the application system after TARE and assessed its potential impact on the tumor absorbed dose (AD) previously planned with ^99mTc MAA SPECT/CT.

We measured ⁹⁰Y-Res using PET/CT in all patients that underwent TARE using ⁹⁰Y-glass-microspheres for non-resectable liver tumors over one year.

⁹⁰Y-Res was measured in 34 patients (HCC n = 22) with 61 injections, 93.1 ± 94.6 MBq [2-437] that was 4.8 ± 3.5% [0.2-13.7] in comparison to the activity measured in the sealed TheraSphere™ vial (ρ = 0.697; p < 0.001).

We reported an average of 5% ⁹⁰Y-Res using PET/CT after TARE with the strongest association to the activity in the TheraSphere™ vial. Therefore, when a high ⁹⁰Y-Res is suspected on the survey meter, a ⁹⁰Y-PET/CT scan of ⁹⁰Y-Res might be useful as a first step to estimate if the target lesion received the recommended AD, especially in HCC patients with borderline tumor dosimetry on the pre-treatment ^99mTc-MAA SPECT/CT.