Tracerlab fxn pro

All PET scans were acquired at the Lawrence Berkeley National Laboratory on a Siemens (Erlangen, Germany) Biograph 6 Truepoint PET/computed tomography (CT) scanner in 3D acquisition mode. FTP was synthesized using a TracerLab FXN-Pro (GE Medical Systems, Milwaukee, WI) synthesis module with a modified protocol based on an Avid Radiopharmaceuticals (Philadelphia, PA) protocol. Participants were injected with 10 mCi of tracer and scanned in list mode from 75 to 105 min post-injection. Data was subsequently reconstructed as 4 × 5-min frames within 80 to 100 min post-injection. PiB was also synthesized according to a previously published protocol [18 (link)]. Immediately after the intravenous injection of approximately 15 mCi of PiB, 90 min of dynamic acquisition frames were obtained (4 × 15, 8 × 30, 9 × 60, 2 × 180, 10 × 300, and 2 × 600 s). Both FTP and PiB images were reconstructed using an ordered subset expectation maximization algorithm with weighted attenuation and smoothed with a 4-mm Gaussian kernel with scatter correction (image resolution = 6.5 × 6.5 × 7.25 mm³).
T1-weighted structural MRI images were acquired on a 1.5-T Siemens Magnetom.
Avanto scanner using a magnetization-prepared rapid gradient echo sequences with the following parameters: repetition time = 2110 ms, echo time = 3.58 ms, flip angle = 15°, voxel size = 1mm isotropic.

[¹⁸F]Fluoride was produced according to the ¹⁸O[p,n]¹⁸F nuclear reaction by irradiation of ¹⁸O-enriched water (97%, Eurisotop) with a IBA Cyclone^® 18/9 cyclotron. A TRACERlab FX NPro synthesis module (GE Medical Systems) was used for the automated radiosynthesis of [¹⁸F]1. The purification and isolation of [¹⁸F]1 were performed using semi-preparative HPLC [Phenomenex Gemini^® C18 column, 5 µm, 250 × 10 mm, with phosphate buffer (pH 2.1)/EtOH (72/28) as the eluent, and a 3.3 mL/min flow rate, λ = 254 nm]. Analytical HPLC for quality control and stability studies was performed using a Waters system [C18 Gemini column, 5 µm, 4.6 × 250 mm, 110 A; NH₄OAc (10 mM)/ACN (55/45) as the eluent; 1 mL/min flow-rate]. The radioTLC analyses were carried out using Merck 60F₂₅₄ silica gel deposited on a glass plate, with CH₃CN/H₂O containing 0.1% TFA (98/02) as the eluent. RadioTLCs were measured on an Elysia Raytest Rita Star 2018203 plate reader. The identity of the radiolabeled compounds was determined via HPLC and TLC analyses by comparison and co-elution with the non-radiolabeled analogue. Pre-conditioned ABX Sep-Pak^® Light QMA cartridges were used as received. Waters Sep-Pak^® tC18 Plus Long Environmental cartridges were used after pre-conditioning with EtOH (10 mL) and water (20 mL).

[¹⁸F]DPA-714 was obtained from the Imaging Probe Development Center, NIH, Rockville, MD and was produced by employing slight modifications to procedures already reported [28 (link)] and using a commercially available GE TRACERLab FX-N Pro synthesizer [29 (link)]. Ready-to-inject, > 99 % radiochemically pure [¹⁸F]DPA-714 (formulated in physiological saline containing ~ 10 % ethanol) was obtained with 30–40 % (n = 12) non-decay-corrected yields and the specific activity at the end of the 70-min radiosynthesis ranged from 48 to 200 GBq/μmol.