Figure 2. Localization of SPIO-labeled cells in implanted rat hearts by MRI.

A) Arrows indicate the location of hypointense regions resulting from the presence of SPIO nanoparticles contained in the implant. Coronal (left), axial (center), and sagittal (left) MRI slices from in vivo cardiac imaging acquisitions were obtained 6 months post-implantation using a 7T magnet. B) Arrows indicate the location of SPIO-labeled cells (hypointense region) in short-axis slices from in vivo cardiac acquisitions taken from two different rats at 6 months and 1 year after surgical implantation of engineered tissues, respectively. These images were obtained using a 4.7T magnet. C) Arrows indicate the location of iron-labeled cells within the implant in an isolated heart that had been implanted with engineered tissues for 1 year. These coronal (left) and axial (right) MRI slices correspond to the in vivo images shown in A).