Page 152 - Cellular Imaging in Regenerative Medicine, Cancer and Osteoarthritis

Chapter 7
octreotide) on day 1, 3, 7, 14, 28 or 56 after induction of OA. At day 3 after OA induction 3 mice were injected with 40 nmol block, DOTA-Tyr3-TATE, 1 minute prior to an injection with 60 MBq/200pmol [111In]In-DTPA-octreotide. Single-photon emission computed tomography (SPECT) was performed on a MILabs VECTor+/CT system (Utrecht, the Netherlands) (34) with an ultra-high sensitivity mouse collimator with fifty-four 2.0 mm pinholes. A 55-minutes SPECT was acquired in list mode along a spiral trajectory, scan mode fine and 10 positions. SPECT was followed by CT (55 keV, 615 mA). SPECT data were reconstructed using the pixel-based ordered subsets expectation maximization (POSEM) developed by MILabs (35) algorithm with 30 iterations, 4 subsets and a voxel size of 0.4 mm. Photopeaks 171 and 245 keV were used, scatter and background were corrected for with the triple-energy-window method (for 171 keV peak % width of 7 and for 245 keV peak % width of 10) (36). CT was reconstructed using filtered back-projection. SPECT and CT were registered; SPECT data were corrected for attenuation using the CT data (34). A post-reconstruction 3-dimensional Gaussian filter was applied. The resulting data was analyzed using inviCRO VivoQuant software (Boston, MA, USA) by quantification of manually drawn regions of interests (ROIs) based on CT. All data were represented as percentage of the injected dose per tissue volume %IA/cm3).
Statistical analysis
For the in vitro experiments, a mixed linear model after log transform was used followed by a Bonferroni’s post hoc comparisons test using PASW Statistics 22.0 (SPSS Inc. Chicago, USA). For the histological staining experiment, differences in CD64 ranks for the time points were determined by a Kruskal-Wallis test. In the uptake experiment and autoradiography the mean values between the different groups (± stimulation, ± block) were compared and analyzed with a Two-way ANOVA. To compare values for DMM and sham surgery (in vivo imaging) the paired t-test was applied. Differences were considered statistically significant when p<0.05.
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