Typical MR images immediately after transplantation of Mn-labeled MNCs and short-term changes of the signal intensity in ischemic rat legs.

<p>A typical horizontal T₁-weighted image (A1), proton density image (A2), and calculated T₂ map (A3) are presented for the same animal immediately after the injection of Mn-labeled MNCs. The images on the right are magnifications of the area inside the white rectangles. Mn-labeled MNCs (white arrows) were injected into the left leg (right side of the images) and saline (white arrow heads) was injected into the right leg (left side of the images). (B) Short-term observation of T₁-weighted signal enhancement in ischemic rat legs is presented. The upper figures show horizontal T₁-weighted MRI after Mn-labeled MNC injection from 0 to 2 days after the transplantation. The lower figures show T₁-weighted MRI after saline injection in the same animal (contralateral leg). The area enclosed by the white dotted lines is an example of a typical region of interest (ROI). At both 1 and 2 days after injection, Mn-labeled MNCs were visualized as a “double-layered structure” that has a positive outline and dark core (B, white arrows). The signal reduction after saline injection soon disappeared (B, white arrow head). (C) Volume change after the MNC injection. The filled triangles indicate volume change at the Mn-labeled MNC injected site and the filled squares correspond to the saline injected site. * Significant difference vs. volume of saline injected control, level of significance P<0.05 for two-way ANOVA with Bonferroni post-hoc test (n = 3).