Reproducibility and repeatability of 18F-(2S, 4R)-4-fluoroglutamine PET imaging in preclinical oncology models.

Area of Science:

• Nuclear medicine
• Molecular imaging
• Oncology research

Background:

• Positron emission tomography (PET) repeatability and reproducibility (R&R) are crucial for its clinical potential.
• While R&R for 18F-FDG PET is established, data for other tracers like 18F-(2S, 4R)-4-fluoro-glutamine (18F-Gln) are limited.
• This study addresses the need for R&R assessment of 18F-Gln, a tracer for glutamine uptake and metabolism.

Purpose of the Study:

• To evaluate the repeatability and reproducibility of 18F-Gln PET imaging.
• To assess the agreement and R&R using statistical methods specifically designed for this purpose.
• To demonstrate the reliability of 18F-Gln for in vivo research applications.

Main Methods:

• Twenty colorectal cancer xenografts in mice were imaged using 18F-Gln PET.
• Three analysts performed tumor uptake analysis on the same images.
• Repeatability was assessed after 6 months, with scans re-ordered.
• Statistical analyses included Bland and Altman (B&A), Gauge Reproducibility and Repeatability (Gauge R&R), and Lin's Concordance Correlation Coefficient.
• An equivalency test was conducted to confirm agreement.

Main Results:

• Gauge R&R indicated that reproducibility and repeatability accounted for 31% and 69% of total measurement error, respectively.
• Bland and Altman analysis showed good repeatability coefficients and agreement limits among analysts.
• Equivalency tests confirmed that repeated measures fell within predefined equivalence limits (± 0.5%ID/g).

Conclusions:

• The study demonstrates high individual analyst and laboratory-level reproducibility and repeatability for 18F-Gln PET.
• Appropriate statistical methods for R&R assessment are critical and should be widely adopted.
• These findings support the use of 18F-Gln for reliable in vivo research.