Micropet r4 rodent scanner

All solvents and chemicals purchased from commercial sources were of analytical grade or better and were used without further purification. DX600, NODAGA‐DX600, and DOTA‐DX600 were custom synthesized by ChinaPeptides Co., Ltd (Shanghai, China) or CSBio (San Diego, California). Sep‐Pak Accell Plus QMA and Sep‐Pak C18‐Light cartridges were purchased from Waters (Ireland). Acrodisc 25 mm syringe filter (0.22 µm) was purchased from Pall Corporation (USA). The product was analyzed by radio‐ high performance liquid chromatography (HPLC) (1200, Agilent, USA) equipped with γ detector (Flow‐count, Bioscan, Washington. D.C., USA), using a C18 column (Eclipse Plus C18, 4.5 × 250 mm, 5µm, Agilent, USA). The product purity was also determined using Radio‐TLC (AR 2000, Bioscan, USA) after radiolabeling. The PET/CT imaging studies of small animals were performed on the Mira PET/CT of PINGSENG Healthcare Inc. (Shanghai, China), or microPET R4 rodent scanner (Siemens) and analyzed by ASIProVM. The Clinical PET/CT scans were obtained on a Biograph mCT Flow 64 scanner (Siemens, Erlangen, Germany) with unenhanced low‐dose CT. ⁶⁸Ga‐HZ20 PET/MRI was performed on a hybrid 3.0T PET/MR scanner (uPMR790, UIH, Shanghai, China) in female volunteers.

Female Naïve Swiss Webster mice (N = 4) were injected with 3.7 MBq/400 μL of ⁴⁴ScCl₃ (or ⁴⁴Sc-NODAGA, or ⁴⁴Sc-citrate) via tail vein catheterization under 2% isoflurane anesthesia. PET imaging was performed for an initial 0.5-h on-camera dynamic image acquisition, and for 10 min static scans at 1-, 2-, and 4-h post-injection using a microPET R4 rodent scanner (Siemens). The imaged mouse was centered in the field of view and maintained under 1–2% isoflurane anesthesia during PET imaging. The calibration factor of the PET scanner was determined with a mouse-sized phantom composed of a cylinder uniformly filled with an aqueous solution of ¹⁸F with a known activity concentration. Acquisitions were recorded using an energy window of 350–700 keV and coincidence-timing window of 6 ns. PET image data were corrected for detector non-uniformity, deadtime, random coincidences and physical decay and images were reconstructed by an iterative 3D maximum a priori algorithm.
The acquired PET images were analyzed using ASIPro software (Siemens). Volume of interest (VOI) analysis of the acquired images was performed using ASIPro software, and the observed value (percent injected activity/cubic centimeter, %IA/cc) represents the mean radiotracer accumulation in the organs. The sequential radioactivity measurements (%IA/cc) were plotted over time post-administration.