Figure 4.

SPECT/CT Scans for cNIS⁺ Cells Visualization

Axial slice of SPECT/CT images at different time points for three different amounts of IM injected (autologous) cells in a same experiment. In the first row, 3 × 10⁶ of NIS⁺ cells were injected into the rBF (red arrow) and no signal from the contralateral muscle was detected. Imaging was repeated at 48 h, 7 days, and 30 days, and no signal was visualized in the rBF muscle. Only symmetric slight spots corresponding to bone, vasculature, testis, or tail were visible. In the middle row, images corresponding to the TC muscles injected with 10 × 10⁶ NIS⁺ cells (right TC) and 10 × 10⁶ of NIS⁻ cells (left TC). Tracking of cells was possible for a week and only for the rTC injected with NIS⁺ cells (red arrow) not detected in the less-sensitive planar acquisition. Symmetric spot in gray-blue corresponds to the tibias. In the last row of images, imaging of lVL muscle injected with 20 × 10⁶ of NIS⁺ cells tracked for a month (red arrow), with a clear focal signal at each image from 4 h to 30 days. No signal was detected in the contralateral muscle. In order to make visually detectable the low amount of radioactivity 30 days after injection, we adjusted the colormaps settings for the illustration to allow the visualization of NIS-expressing cells, but also leading to increased level of other structures (right column).