[¹⁸F]FNDP PET neuroimaging test-retest repeatability and whole-body dosimetry in humans

Soluble epoxide hydrolase (sEH) is an enzyme that shapes immune signaling through its role in maintaining the homeostasis of polyunsaturated fatty acids and their related byproducts. [¹⁸F]FNDP is a radiotracer developed for use with positron emission tomography (PET) to image sEH, which has been applied to imaging sEH in the brains of healthy individuals. Here, we report the test-retest repeatability of [¹⁸F]FNDP brain PET binding and [¹⁸F]FNDP whole-body dosimetry in healthy individuals.

Seven healthy adults (4 men, 3 women, ages 40.1 ± 4.6 years) completed [¹⁸F]FNDP brain PET on two occasions within a period of 14 days in a test-retest study design. [¹⁸F]FNDP regional total distribution volume (V_T) values were derived from modeling time-activity data with a metabolite-corrected arterial input function. Test-retest variability, mean absolute deviation, and intraclass correlation coefficient (ICC) were investigated. Six other healthy adults (3 men, 3 women, ages 46.0 ± 7.0 years) underwent [¹⁸F]FNDP PET/CT for whole-body dosimetry, which was acquired over 4.5 h, starting immediately after radiotracer administration. Organ-absorbed doses and the effective dose were then estimated.

The mean test-retest difference in regional V_T (ΔV_T) was 0.82 ± 5.17%. The mean absolute difference in regional V_T was 4.01 ± 3.33%. The ICC across different brain regions ranged from 0.92 to 0.99. The organs with the greatest radiation-absorbed doses included the gallbladder (0.081 ± 0.024 mSv/MBq), followed by liver (0.077 ± 0.018 mSv/MBq) and kidneys (0.063 ± 0.006 mSv/MBq). The effective dose was 0.020 ± 0.003 mSv/MBq.

These data support a favorable test-retest repeatability of [¹⁸F]FNDP brain PET regional V_T. The radiation dose to humans from each [¹⁸F]FNDP PET scan is similar to that of other ¹⁸F-based PET radiotracers.