Abstract
1797
Objectives: Transarterial embolisation of branches of the hepatic artery with biocompatible Y-90-labeled microspheres (SIR Spheres®) has recently been established in Europe, offering a promising alternative treatment option for patients with extensive liver metastases and hepatocellular carcinoma (HCC). Aim of this study was to clarify, whether and to which extent metabolically active liver lesions can be approached with this type of therapy, which is primarily based on hemodynamic aspects.
Methods: In a subset of 16 patients (7 women, 9 men, mean age: 59 ± 12 yrs) the metabolic activity of multiple liver metastases/HCC lesions was determined with F-18-FDG-PET/CT prior to treatment with SIR Spheres®. Furthermore, SPECT investigations were performed to document the pretherapeutic distribution of Tc-99m-MAA and the posttherapeutic distribution of SIR Spheres®. In FDG positive lesions maximum SUV, size, and portal venous contrast enhancement (CT) were correlated visually and semi-quantitatively with the findings of MAA-SPECT (maximum tumor uptake/mean uptake in normal liver tissue) and posttherapeutic Bremsstrahlung SPECT.
Results: 58 of 62 FDG positive, focal lesions were clearly delineated in the MAA- and posttherapeutic SPECT scans. In these lesions, uptake of Tc-99m-MAA was on average 4 ± 3 times higher as compared to normal tissue. The uptake intra-individually correlated with the maximum SUV and with the lesion size (r=0.445, p=0.01), however, no significant correlation with the contrast enhancement in CT images was found (p=0.198). The distribution of SIR Spheres® in the posttherapeutic scans closely matched the one observed in the pretherapeutic MAA-SPECT scans. In large metastases, deposition of SIR Spheres® was confined to the tumor rim with sparing of the central part. 4 patients presented with diffuse infiltration of the liver (>30 single lesions). In those patients single focal lesions could not be clearly delineated in the pre- and posttherapeutic scans.
Conclusions: Pretherapeutic SPECT scans with transarterially administered MAA allowed to accurately predict the posttherapeutic regional distribution of SIR Spheres®. Since almost all metabolically active lesions as assessed by PET/CT showed increased deposition of SIR Spheres® after treatment, it can be assumed, that most of these lesions are accessible for SIR Spheres® therapy.
- Society of Nuclear Medicine, Inc.