Figure 4.

Octreotate Modified Iron Oxide NP for Targeted Cerenkov Quenching. OCT-Cy5.5-SPIO were administered to mice bearing bilateral xenografts with (C6 hSSTr₂) or without (C6 WT) hSSTr₂ expression. (A) The fluorescent nanoparticles demonstrate the specific uptake of this new probe at the positive, hSSTR2-expressing, tumor. (B) Prior to nanoparticle administration, 11.1 MBq of [18F]-FDG was given for PET and CL imaging. Greater glycolytic activity in the hSSTr₂+ tumor CL of a representative animal is presented in left and right sagittal views with axial PET through the tumors. CL when normalized for percent injected dose per gram of [¹⁸F]-FDG, is not significantly different between the two tumor types. (C) One day following dosing with Cy5.5-SPIO-OCT, the imaging was repeated. Now we are able to again obtain the quantitative information from functional PET imaging, but with the targeted quenching NP we are also able to add a layer of molecularly specific information to distinguish the tumors.