Fig. 2.

Tracking of BBM in mice. MRI and SPECT tests were used to track BMM in tissue after intravenous injection of labeled cells. Top: Time series of ${\text{T}}_2^{\ast }$ weighted MRI after super paramagnetic iron oxide (Feridex) labeled BMM. This demonstrates visible signal (in blue) due to signal loss caused by labeled cell accumulation in the spleen (upper) and liver (lower). The series of photomicrographs shows preinjection (time 0), and 1, 3, and 5 days after injection of the Feridex-labeled BMM. Bottom: Co-registration of ¹¹¹In/Feridex-labeled BMM by MRI and SPECT. BMM were dual-labeled with Feridex and ¹¹¹In and transferred to recipient mice. Recipients were anesthetized, positioned in custom built, MRI/SPECT compatible holders with attached fiducial markers and serial acquisitions of MRI and SPECT scans were performed on day 1 after transfer. SPECT data were interpolated to the resolution of the MRI data and fiducial markers were used for scaling and alignment. Reconstructed SPECT images (green) were co-registered and overlaid to MRI scans (red). Displayed co-registered images are 390 μm slices containing spleen (Spl) and kidney (Kid) (left panel) and liver (Liv) (right panel), and show areas of radioactive intensities of ¹¹¹In-labeled BMM in SPECT images (green) that correspond to loss of MRI signal.