Evaluation of 18F-Fluciclovine PET for Monitoring Glioblastoma Tumor Volumes

Overview

This prospective cohort study assessed tumor volumes in glioblastoma patients using 18F-Fluciclovine PET compared to conventional MRI sequences at multiple treatment timepoints. Findings indicate that 18F-Fluciclovine PET delineates hypermetabolic tumor volumes larger than contrast-enhancing MRI but smaller than FLAIR volumes, with volumes decreasing post-surgery and radiation yet not fully resolving.

Background

Glioblastoma is the most aggressive primary malignant brain tumor in adults, with poor survival rates despite multimodal therapies. Conventional MRI is the standard for treatment planning and monitoring but has limitations in accurately defining tumor extent. 18F-Fluciclovine PET imaging offers metabolic information with advantages over other tracers, including lower background uptake in normal brain tissue and dual amino acid transporter targeting, potentially improving glioma detection. Prior studies have shown 18F-Fluciclovine PET volumes exceed contrast-enhancing MRI volumes preoperatively, but its utility post-treatment remains underexplored.

Data Highlights

Key Findings

• 18F-Fluciclovine PET consistently identifies tumor volumes larger than contrast-enhancing T1-weighted MRI but smaller than FLAIR hyperintense regions across all treatment timepoints.
• Post-surgical and post-radiation therapy imaging shows a decrease in 18F-Fluciclovine PET-defined tumor volumes, reflecting treatment response.
• Residual hypermetabolic volumes persist after therapy, consistent with glioblastoma's infiltrative nature.
• 18F-Fluciclovine PET uptake correlates with tumor presence beyond contrast-enhancing areas, supporting its sensitivity in detecting non-contrast-enhancing tumor components.
• The dual amino acid transporter mechanism of 18F-Fluciclovine may contribute to improved detection of heterogeneous tumor metabolic profiles compared to other PET tracers.
• Study enrollment was limited (n=8) due to external factors, but longitudinal imaging data provide valuable insights into tumor volume dynamics during treatment.

Clinical Implications

18F-Fluciclovine PET imaging can enhance glioblastoma treatment monitoring by more accurately delineating tumor extent beyond conventional MRI contrast enhancement. This may inform surgical planning and radiotherapy targeting to better address infiltrative tumor regions while sparing healthy tissue. Incorporating 18F-Fluciclovine PET into clinical workflows could improve assessment of treatment response and residual disease.

Conclusion

18F-Fluciclovine PET provides complementary metabolic information that surpasses conventional MRI in defining glioblastoma tumor volumes throughout treatment. Its ability to detect residual infiltrative tumor post-therapy highlights its potential utility in guiding personalized management strategies.

References

1. Karlberg et al. 18F-Fluciclovine PET in Glioblastoma -- Hypermetabolic volumes exceed MRI contrast-enhancing regions
2. Fatania et al. 18F-Fluciclovine PET post-surgery and during chemoradiation -- Exploratory study
3. FDA 18F-Fluciclovine Approval and Orphan Drug Designation
4. STROBE Checklist for Cohort Studies