Small Animal PET Imaging Protocols

In order to investigate the scanner’s capability to image small animals, we imaged three C57 BL/6 J mice with three different radiotracers. One mouse was administered 18.5 kBq of ¹⁸F-sodium fluoride via IV tail injection, anesthetized with 1.5% isoflurane following 1 h of awake uptake and then scanned for 30 min. Images were reconstructed using four different algorithms: 2D FBP (ramp filter, cutoff at Nyquist frequency) preceded by Fourier rebinning of the 3D sinograms, 3DRP (no filter), OSEM 2D (16 subsets, 4 iterations) and fast OSEM3D/MAP (2 OSEM3D iterations, 18 MAP iterations). All images were 128 × 128 pixels with a 0.77 mm pixel size. The second mouse was injected with 32.2 MBq of ¹⁸F-FDG and scanned for 60 min, starting at 70 min post-injection. The animal was fasted for 24 h before ¹⁸F-FDG administration. A third mouse was injected IV with 32.7 MBq of ¹⁸F-fallypride (dopamine D2/D3 radioligand) and was imaged for 150 min. In addition to the emission scans, transmission images were acquired for each animal using the Co-57 source and attenuation maps were constructed after sorting in sinograms using SSRB. All animal images were reconstructed using FBP with a ramp filter and cutoff at Nyquist frequency.