PET(SPECT)/MR/optical imaging.(a) Reflection and confocal images of A431 cells labeled with NOTA-Au-IONP-Affibody (left). NOTA = 1,4,7-triazacyclononane-1,4,7-triacetic acid; IONP = iron oxide nanoparticle. Quantification analysis of the cellular uptake with NOTA-Au-IONP, NOTA-Au-IONP-Affibody, and Affibody blocked NOTA-Au-IONP-Affibody in A431 cells after incubation (right). (b)In vivo decay-corrected whole-body coronal PET images of A431 tumor bearing mice (n = 3/group) (left). Quantitative analysis of PET images of tissues and organs (right). (c)In vivo T2-weighted MR images of A431 tumor bearing mice (left). Quantification of MRI signal intensity before and at 4 h and 48 h after injection of 64Cu-NOTA-Au-IONP-Affibody and Affibody (right). (Adapted with permission from ref. 89. Copyright (2013) Elsevier).