U spect4ct

SCID (Envigo, Gannat, France) or Tsg SCID-CD89 mice (J. Leusen, University Medical Center Utrecht, The Netherlands) were grafted as described previously for nude mice. ^99mTc-anti-CEA pIgA-SH, ^99mTc-irrelevant pIgA-SH or ^99mTc-anti-CEA IgG-SH (60 MBq) was injected IV. Anaesthesia induction was achieved using 3% isoflurane and animals were maintained under general anaesthesia with 1,8% isoflurane for the duration of imaging. Air/Oxygen (50%/50%, 1,4 l/minutes) was maintained throughout anaesthesia induction and maintenance. Acquisitions were performed 4 h post-injection with a MicroSPECT/CT (U-SPECT4/CT, MILabs, Utrecht, The Netherlands). Images were acquired during 30 minutes and energy windows were set over the 140 keV peaks (±20%). The SPECT resolution with ^99mTc is less than 1 mm. Images were analysed and uptake were quantified in Region of Interest (ROI) with PMOD Software (PMOD Technologies, Zürich, Switzerland).

Hind limbs and knee joints were dissected from mice and rats, fixed overnight in 4% paraformaldehyde and analyzed by MILabs U-SPECT4CT with default parameters.

CT scanning was performed on a small animal-dedicated SPECT/CT scanner (U-SPECT⁴CT, MILabs) using one bed position at the maximal field of view (total body mode) with 180 projections (0.5° step angle, single projection per step) of 40 ms with a beam energy of 50 kV and 0.43 mA. The camera was calibrated with those parameters to provide the radiodensity in Hounsfield units (HU). Images were reconstructed at 100 μm of isotropic voxel size with Gaussian filter at 150 μm full-width at half-maximum using the manufacturer's software.