Phantom-based optimization of [¹⁸F]fluciclovine neuro-oncology imaging on a high-resolution dedicated head PET...

This study aimed to establish and evaluate two evidence-based reconstruction protocols for [¹⁸F]fluciclovine PET on a high-resolution dedicated head PET system: a time-efficient protocol for routine clinical use, and a high-quality protocol designed to maximize small-lesion detectability.

A brain-tumor phantom (target-to-background ratio, 5:1) was scanned on a dedicated head PET scanner (BresTome, Shimadzu). Using a 60-min list-mode acquisition, parameters were optimized for two visually defined pathways (10-min clinical-efficiency; 30-min high-quality). The optimization sequence involved optimizing the relaxation factor (β) using mean percent contrast (%contrast_mean), followed by a comparison of post-reconstruction filters (non-local means [NLM] and Gaussian) by maximizing a local contrast-to-noise ratio (CNR), guided by the Rose criterion. The final protocols were evaluated against Japanese brain-tumor phantom criteria for key performance metrics, including maximum percent contrast (%contrast_max), relative recovery coefficient (RC), quantitative accuracy (SUV_TOT), and uniformity (SD_ΔSUVmean).

Two distinct protocols were established. The 10-min clinical-efficiency protocol was optimized with β = 60 and an NLM filter (intensity 1.5), which provided the best CNR for the 7.5-mm sphere. The 30-min high-quality protocol was optimized with β = 70 and an NLM filter (intensity 1.0), which yielded the highest CNR for the 5-mm sphere. The 30-min protocol was required for enhanced visibility of the 5-mm sphere. Both protocols met the Japanese criteria for %contrast_max, relative RC, and SUV_TOT, whereas SD_ΔSUVmean did not meet the criterion. Supplementary reconstructions of the full 60-min dataset met the SD_ΔSUVmean criterion. In two representative clinical cases, application of the optimized protocols yielded clinically interpretable images with clear visualization of tumor uptake.

This study establishes a dual-pathway framework for [¹⁸F]fluciclovine PET. We recommend the 30-min high-quality protocol (β = 70, NLM intensity = 1.0) as the preferred option when feasible to maximize small-lesion detectability. The 10-min clinical-efficiency protocol (β = 60, NLM intensity = 1.5) serves as a practical, time-saving alternative for patients with limited tolerance. This approach provides a foundation for personalizing clinical protocols based on specific imaging needs and highlights the importance of standardizing uniformity assessment using an appropriate longer-duration reference acquisition for modern high-resolution PET systems.