Discordant patterns of anterior abdominal wall radiotracer accumulation in yttrium-90 selective internal radiation therapy: implications for pretherapeutic planning and posttreatment monitoring.

PURPOSE: This study aimed to investigate the differential patterns of anterior abdominal wall (AAW) radiotracer accumulation using pretherapeutic technetium-99m macroaggregated albumin ( 99m Tc-MAA) single photon emission computed tomography/computed tomography (SPECT/CT) and posttherapeutic yttrium-90 ( 90 Y) positron emission tomography/CT (PET/CT) imaging in 90 Y resin microspheres selective internal radiation therapy (SIRT).

MATERIALS AND METHODS: A retrospective analysis was conducted on 204 patients with unresectable liver malignancies who underwent SIRT between August 2022 and November 2024. Pretherapeutic evaluation included diagnostic angiography and 99m Tc-MAA imaging. Posttherapeutic 90 Y-PET/CT was performed within 24 h of treatment to verify microspheres distribution. Patients with AAW accumulation on 99m Tc-MAA images or 90 Y-microspheres PET/CT images were analyzed, and follow-up results for at least 3 months served as reference standards.

RESULTS: Among 204 patients, 21 (10.3%) showed AAW accumulation on 99m Tc-MAA images or 90 Y-microspheres PET/CT images. Concordant findings between 99m Tc-MAA images and 90 Y-PET/CT images were observed in 11(11/21, 52.4%) cases, while five cases (5/21, 23.8%) showed accumulation only on 90 Y-PET/CT images, and the other five cases (5/21, 23.8%) showed accumulation only on 99m Tc-MAA images. The hepatic falciform artery (HFA) was found in two patients. Mild abdominal pain was observed in four patients, and only one patient experienced abdominal dermatitis, which resolved spontaneously. The remaining patients did not experience any relevant side effects during the follow-up period.

CONCLUSION: AAW-related complications were infrequent and mild, suggesting that a patent HFA may not be considered a contraindication for SIRT; however, discordance between 99m Tc-MAA and 90 Y-PET/CT highlights the need for vigilant posttreatment monitoring, even in cases without pretherapeutic AAW accumulation.