RT Journal Article SR Electronic T1 Spatial Resolution and Image Quality of Unique Radionuclides for PET Imaging JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 3321 OP 3321 VO 63 IS supplement 2 A1 Sharon Samuel A1 Solana Fernandez A1 Jennifer Bartels A1 Jennifer Pyles A1 Hailey Houson A1 Brian Wright A1 Anna Sorace A1 Suzanne Lapi YR 2022 UL http://jnm.snmjournals.org/content/63/supplement_2/3321.abstract AB 3321 Introduction: Promising investigational radiopharmaceuticals have continued to be developed for PET imaging incorporating both conventional and non-conventional radionuclides produced for molecular imaging. These specialized tracers allow for new approaches to imaging, theranostics, and therapy, but spatial resolution differences in these radionuclides vary based on their positron range and other decay parameters, leading to variation in image quality and potential difficulties with scan interpretation. The purpose of this study was to evaluate the saturation limits, spatial resolution, and image quality of several radionuclides produced in a TR24 cyclotron or a generator using a Derenzo phantom imaged on a Sofie GNEXT preclinical PET scanner. Methods: Radionuclides 18F, 68Ga, 89Zr, 45Ti, 64Cu, 52Mn, 43Sc and 55Co were produced by either eluting a 68Ge generator or on a TR24 cyclotron. Radionuclides were diluted and a Derenzo phantom with varying size cylindrical phantoms was filled with a total activity of 300 μCi. Static PET images were collected for 60 minutes using an energy window of 350-650 keV followed by a CT acquisition for attenuation correction. PET images were reconstructed using the 3-dimensional ordered subset expectation maximization (3D-OSEM) algorithm, with random, attenuation, and decay correction. CT images were reconstructed using a Modified Feldkamp algorithm. PET images were converted to SUVs during post processing using VivoQuant software. Line functions were applied to images to produce intensity plots and the full width half maximum (FWHM) was quantified as a measure of relative spatial of resolution. Calculated contrast-to-noise (CNR) ratios were compared between different size cylinder ROIs in the Derenzo phantom as a measure of image quality for each radionuclide. In a separate acquisition, single tube phantoms filled with radionuclide amounts ranging from 50 μCi to 1500 μCi in 20 mL of solution were used to evaluate the saturation limit of the PET scanner by collecting static images for 10 minutes, reconstructing, and measuring ROIs applied to the volume of the phantom. Results were plotted as measured ROI activity vs actual activity in the phantom. Results: Results show FWHM increased with a decrease in photon energy; for the 3.2 mm diameter rod in the Derenzo phantom, relative resolution measurements were 2.65 ± 0.12 mm, 2.67 ± 0.05 mm, 2.75 ± 0.21 mm, 2.88 ± 0.14 mm, 2.93 ± 0.26 mm, 3.01 ± 0.27 mm, 3.13 ± 0.3 mm, and 4.17 ± 0.34 mm for 64Cu, 18F, 52Mn, 45Ti, 43Sc, 55Co, 89Zr, and 68Ga, respectively. Saturation limits of radionuclides imaged on the preclinical scanner ranged from 250 μCi for 52Mn to greater than 1500 μCi for 64Cu, with most radionuclides reaching saturation limits between 500 μCi and 750 μCi. 64Cu showed a final saturation limit between 2000 μCi and 2500 μCi.Conclusions: The evaluations of radionuclides in this study show that the spatial resolution and image quality are constrained by both the intrinsic properties of the radionuclides and the detector limits on the scanner. Positron range, positron energy, instrument sensitivity, and study applications are considerations which can aid in improving image quality for each radionuclide used for imaging studies, resulting in more reliable and repeatable acquisitions for in vivo preclinical and clinical applications.