(a) Preparation of PET/MRI dual-modality probe DOTA-IO-RGD. DOTA = 1,4,7,10-tetraazacyclododecane-N,N’,N”,N”’-tetraacetic acid; IO = Iron Oxide; RGD = arginine-glycine-aspartic; PEG-MAL = poly(ethylene glycol)-maleimide; PASP = polyaspartic acid. (b) Decay-corrected whole-body coronal PET images of human U87MG tumor-bearing nude mouse at 1, 4, and 21 h after injection of 64Cu-DOTA-IO, 64Cu-DOTA-IO-RGD, or 64Cu-DOTA-IO-RGD (left). Time-activity curves of U87MG tumors after injection of 64Cu-DOTA-IO, 64Cu-DOTA-IO-RGD, or 64Cu-DOTA-IO-RGD with blocking dose of c(RGDyK) (n = 3/group) (right). (c) T2-weighted MR images of U87MG tumor-bearing nude mice before injection of IO nanoparticles (c-1 and c-5) and at 4 h after tail-vein injection of DOTA-IO (c-2 and c-6), DOTA-IO-RGD (c-3 and c-7), and DOTA-IO-RGD with blocking dose of c(RGDyK) (c-4 and c-8). (d) Prussian blue-stained U87MG tumor, liver, and spleen sections after injection of 64Cu-DOTA-IO-RGD, 64Cu-DOTA-IO, and 64Cu-DOTA-IO-RGD with blocking dose of c(RGDyK). IO was stained as blue spots in figure (magnification, 200x). (Adapted with permission from ref. 82. Copyright (2008) The Society of Nuclear Medicine and Molecular Imaging).