A Pilot Study on Hepatobiliary Scintigraphy to Monitor Regional Liver Function in ⁹⁰Y Radioembolization

Radioembolization is increasingly used as a bridge to resection (i.e., radiation lobectomy). It combines ipsilateral tumor control with the induction of contralateral hypertrophy to facilitate lobar resection. The aim of this pilot study was to investigate the complementary value of hepatobiliary scintigraphy (HBS) before and after radioembolization in the assessment of the future remnant liver. Methods: Consecutive patients with liver tumors who underwent HBS before and after ⁹⁰Y radioembolization were included. Regional (treated/nontreated) and whole liver function and volume were determined on HBS and CT. Changes in regional liver function and volume were correlated with the functional liver absorbed doses, determined on ⁹⁰Y PET/CT. In addition, the correlation between liver volume and function change was evaluated. Results: Thirteen patients (10 hepatocellular carcinoma, 3 metastatic colorectal carcinoma) were included. Liver function of the treated part declined after radioembolization (HBS-pre, 4.0%/min/m²; HBS-post, 1.9%/min/m²; P = 0.001), whereas the function of the nontreated part increased (HBS-pre, 1.4%/min/m²; HBS-post, 2.8%/min/m²; P = 0.009). Likewise, treated volume decreased (pretreatment, 1,118.7 cm³; posttreatment, 870.7 cm³; P = 0.003), whereas the nontreated volume increased (pretreatment, 412.7 cm³; posttreatment, 577.6 cm³; P = 0.005). Bland-Altman analysis revealed a large bias (29%) between volume decrease and function decrease in the treated part and wide limits of agreement (-7.7%-65.6%). The bias between volume and function change was smaller (±6.0%) in the nontreated part of the liver, but limits of agreement were still wide (-117.9%-106.7%). Conclusion: Radioembolization induces regional changes in liver function that are accurately detected by HBS. Limits of agreement between function and volume changes were wide, showing large individual differences. This finding indicates that HBS may have a complementary role in the management of patients for radiation lobectomy.