Vivoquant 4

The ¹¹¹In-labeled NM-scFv was IV injected into three mice at a dose of 152.5 µg of siRNA per kg of mouse at 3.7 ± 0.74 MBq of radioactivity. At 40 min post-injection, the mice were sacrificed and SPECT-CT images were acquired with a NanoSPECT/CT (Mediso, Budapest, Hungary). Helical SPECT scans with 24 projections of 60 s were acquired before the CT scans with the following parameters: exposure time at 500 m, 55 KVp, 145 µA, 180 projections and pitch set to 1. The reconstruction of SPECT images was performed on the HiSPECT NG software (Scivis GmbH, Göttingen, Germany) and that of CT images was achieved on InVivoScope software (Invicro, Boston, MA, USA). The accumulation of radioactivity in major organs was also quantified using VivoQuant 4.0 (Invicro, Boston, MA, USA) thanks to a mouse phantom filled with known ¹¹¹In activity. The final results were presented as mean values ± standard deviation.

Three sequential PET/CT scans were performed, using Mediso’s LFER150 PET/CT scanner, at 6, 12, and 18/19 weeks after M. tuberculosis infection with the last scan prior to necropsy. PET/CT scanning was essentially performed as described earlier (66 (link)). Briefly, we performed FDG PET/CT scans for each anesthetized macaque using the breath-hold technique (69 (link), 70 (link)). Animals were anesthetized and intubated under supervision of a veterinarian as per approved IACUC protocols. All the animals received an intravenous injection of 5 mCi of FDG (71 (link)) in the right arm, procured from Cardinal Health radio pharmacy. Single- and a double–field of view CT scans were performed using breath-hold as described (72 (link)). The single–field of view (single-FOV) CT scan was performed with bread-hold as described previously (34 (link)) to obtain a clear reconstructed image of the lung; the 2-FOV scan was used for the reconstruction of the PET as the material map. Two FOV PET scans were acquired after a 45-minute FDG uptake period. Images were visualized using Interview Fusion 3.03 (Mediso) and reconstructed using Nucline nanoScan LFER 1.07 (Mediso) with parameters as described (73 (link)). 3D image analysis was performed using VivoQuant 4.0 (Invicro) (74 (link)) to calculate the SUV in the M. tuberculosis lesions observed in the lung.

Images were analyzed using VivoQuant 4.0 pre-clinical image post-processing software (Invicro, Boston, MA, USA). PET–MRI raw data were processed using the standard software provided by the manufacturers. PET data were acquired in list mode, histogrammed by Fourier re-binning, and reconstructed using a 3D-OSEM algorithm, with standard corrections for random coincidences, system response, and physical decay applied. The PET/MR scanner-reconstructed PET images were quantitated using a system-specific ¹⁸F calibration factor to convert reconstructed count rates per voxel to activity concentrations (%ID/g). Manual tissue segmentation of BAT and automatic segmentation of WAT were performed on co-registered 3D MR images. The regional ROIs were then used to calculate tissue radiotracer uptake from the reconstructed PET images (Figure 6A) [64 (link)].

Images were analyzed with VivoQuant 4.0 software (inviCRO, Boston, MA, USA) using a custom script pipeline (available upon request). An arbitrary threshold of 5 SUV was applied to highlight regions of increased uptake on the SPECT images. The stomach, an endogenous site of pertechnetate uptake, was manually removed from the thresholded region. Regions of uptake 64 voxels (1mm³) or greater localized within the liver by the coregistered CT image were included in the final region of interest (ROI), while smaller regions were filtered out to reduce false positives. Total apparent volume of the ROI (V_SUV5), number of separate lesions (n), maximum uptake value (SUV_max), and the summed uptake values of each voxel in the ROI (SUV_sum) were quantified.