Vivoquant 3

For mice included in the studies described in Section 2.1 and Section 2.2, the BBB opening was evaluated by SPECT/CT imaging using [99mTc]Tc-DTPA as radiotracer 0.5 h, 3 h and 24 h post BBB permeabilization. For animals of the study described in Section 2.2, this procedure was also performed 24 h before BBB permeabilization.
[99mTc]Tc-DTPA was administered via an intravenous injection of 50 μL of radioactive tracer (20 MBq) in isotonic and pyrogen-free solution using an insulin syringe (27G). Thirty minutes after injection, the SPECT/CT acquisition was done for 20 min under anesthesia with 1.5% vol% isoflurane (IsoVet^®, Laboratoire Osalia, Paris, France) using a NanoSPECT/CTplus^® camera and the Nucline^® 1.02 acquisition software (Mediso Medical Imaging System Ltd., Budapest, Hungary). SPECT and CT DICOM files were fused for reconstruction and image processing was carried out with VivoQuant^® 3.5 and InvivoScope^® 2.00 reconstruction software (InviCRO, Boston, MA, USA) to assess tracer uptake in the brain.
For the pilot study, statistical analysis was performed using two-way ANOVA (uncorrected Fisher’s LSD test). For the hemispheric BBB permeabilization study, statistical analysis was performed using two-way ANOVA with Dunnett’s multiple comparisons test of each time point vs. the basal value (−24 h).

On post-operative days 7, 21 and 56, rabbits were placed under anesthesia, weighed and 14.04±1.7 MBq ¹⁸F-FDG was injected intravenously via the ear vein. Static images were acquired 45 min following tracer injection. PET images were obtained using a single static 15-min acquisition followed by CT imaging for attenuation correction and anatomical co-registration using the nanoScan PET/CT (Mediso Systems, USA), modified from previously described methods (Davis et al., 2009 (link)). PET-CT images were reconstructed and co-registered using VivoQuant 3.5 (InviCRO). 3D spherical volumes of interest were drawn to measure ¹¹F-FDG-PET signal surrounding infected hardware and in an uninfected reference point (anteriorly to L4). SUVs were derived. Uptake into bone and soft tissue was determined based on an ROI surrounding the hardware and using CT-derived thresholds for bone [>700 Hounsfield units (HU)]. The implant was excluded from the images prior to analysis. SUVs were derived and ratios between bone and soft tissue calculated.

The in vivo measurement of the near-infrared autofluorescence (NIRAF) was performed using a FLECT/CT (Trifoil InSyTe, Chatsworth, CA, USA), seven weeks after the TS surgery, as described previously [9 ]. Briefly, the mice were anesthetized and the fur removed as required, and the animals then placed in the imaging chamber, where they remained anesthetized throughout the imaging procedure (~70 min). The X-ray CT scans were performed using the following settings: 30 kV for tube voltage, 500 µA for tube current, and 150 ms exposure time. The fluorescence scans were performed using a 730 nm excitation laser and 803 nm filter in step-and-shoot scanning mode, with 29 source angles per slice and 500 ms exposures, and subsequent fluorescence attenuation scans were performed in continuous mode. A reconstructed 3D image of the x-ray scan detailing the anatomy of the mouse was overplayed onto the corresponding fluorescence-reconstructed image by VivoQuant 3.5 (InviCRO, Needham, MA, USA).