90Y microsphere treatment of unresectable liver metastases: Changes in 18F-FDG uptake and tumour size on PET/CT

Maren Bienert, Barry McCook, Brian I. Carr, David A. Geller, Mike Sheetz, Cecilia Tutor, Nikhil Amesur, Norbert Avril

Research output: Contribution to journalArticlepeer-review


Purpose: The intra-arterial administration of 90Y microspheres is a new palliative treatment option for unresectable liver metastases. The aim of this study was to quantitatively assess changes in FDG uptake and tumour size following 90Y microsphere treatment (SIR-Spheres) using 18F-fluorodeoxyglucose (FDG) PET/CT imaging. Methods: Five patients with unresectable liver metastases who had failed multiple prior chemotherapy regimens received seven 90Y microsphere treatments to a single liver lobe. All patients underwent a baseline PET/CT scan prior to treatment, as well as up to four follow-up PET/CT scans. The tumour area of 30 liver metastases was measured on CT and the FDG uptake was semiquantitatively assessed by calculation of standardised uptake values (SUVs). A total of 18 FDG-PET/CT scans were performed. Results: The SUVs in the 30 treated liver metastases decreased from 6.5±2.3 at baseline to 4.2±1.8 after the first follow-up PET/CT scan (p=0.001). In contrast, the SUVs of untreated metastases increased slightly from 7.2±2.3 to 8.0±0.8. There was no difference in FDG uptake in treated versus untreated normal liver tissue. Using a previously defined threshold of 20% decrease in SUV from baseline to determine response, 20 out of 30 liver metastases were considered to have responded at the first follow-up PET/CT scan approximately 1 month after treatment. In these metastases, the SUV decreased by 47±12%, compared with a slight increase by 5.9±19% in ten non-responding metastases (p=0.0001). The changes in tumour size did not correlate with changes in FDG uptake. On the first follow-up PET/CT scan, the tumour area on CT increased by 3.1±57% in treated metastases compared with 23.3±32% in untreated metastases. A wide range of post-treatment changes of target lesions was observed on CT, including an increase in the size of hypodense lesions, necrotic features and complete resolution of CT abnormalities. Conclusion: The metabolic information obtained from FDG-PET/CT seems to provide a more accurate and earlier assessment of therapy response following 90Y microsphere treatment than does the anatomical CT information.

Original languageEnglish
Pages (from-to)778-787
Number of pages10
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Issue number7
Publication statusPublished - Jul 2005


  • Y microspheres
  • FDG
  • Liver metastases
  • PET/CT
  • SUV

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology


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