Assessment of Hypoxia Before Radioembolization Treatment With 18 F-FMISO PET : ARTE-MISO Trial

Transarterial radioembolization (TARE) is a therapeutic option for patients with liver tumors. However, factors responsible for treatment resistance in TARE remain largely unknown. In this study, we aimed to investigate the role of hypoxia in the treatment response of liver tumors using 18 F-FMISO PET imaging before TARE.

This single-center prospective study included 25 patients with primary or metastatic liver tumors imaged with 18 F-FMISO PET/CT before TARE and treated with 90 Y resin microspheres. Posttreatment response was assessed with 18 F-FDG PET imaging. Hypoxia status was evaluated by calculating the tumor-to-muscle (T/M) and tumor-to-blood pool (T/BP) ratios. Absorbed dose metrics were derived from 90 Y PET/MRI imaging post-procedure. Lesions were categorized by response as complete responders (CR), partial responders (PR), stable disease (SD), and progressive disease (PD). Statistical analyses included ROC curve analysis, χ2 tests, and regression models to determine predictors of treatment response.

Among 25 patients (mean age: 60.4 ± 12 y, 56% males), 54 18 F-FDG-avid lesions were evaluated. The median absorbed dose (Dmean) was 114.8 Gy for CR, 98.9 Gy for PR, 56.7 Gy for SD, and 78.3 Gy for PD. Significant differences in Dmean ( P = 0.013) and T/BP ratios ( P = 0.011) were observed between responder and nonresponder groups. High Dmean lesions (>89 Gy) had a response rate of 86%, compared with 56% in low Dmean lesions. Hypoxic lesions (T/BP >1.29) showed a 57% response rate, while non-hypoxic lesions (T/BP <1.29) showed a 91% response rate. In combined analyses, while non-hypoxic/high Dmean lesions had the highest response rates (93%), hypoxic/low-dose had the lowest response rate (39%).

In this study, we have observed that both mean absorbed radiation dose and hypoxia status are significant predictors of response to treatment after radioembolization of liver tumors. While larger studies are needed to confirm these findings, this pilot study may pave the way for further personalized treatments to achieve better results for radioembolization.