Kruttwig, K., Brueggemann, C., Kaijzel, E., Vorhagen, S., Hilger, T., Löwik, C., et al. (2010). Development of a three-dimensional in vitro model for longitudinal observation of cell behavior: monitoring by magnetic resonance imaging and optical imaging. Molecular Imaging and Biology, 12(4), 367-376. doi:10.1007/s11307-009-0289-x.