Tracking of infused cells. (A) T2-weighted image of a rat infused with 1.0 × 106 iron-labeled cells in 0.5 ml within 3 minutes. (B) T2* image at the same level. Cell infusion evokes hypointense spots on T2* sequence primarily located in the ipsilateral hemisphere within and around the lesions seen in T2. Prussian blue staining reveals cells inside the microvessel and attached to the vascular wall (C). It is also evidence that cells had migrated across the vascular wall and disaggregated (D). Scale bar for (A, B) is 2 mm, and for (C, D) is 20 μm.