Figure 1.

Biodistribution imaging. (A) Nanomedicines labeled with radioisotopes or optical imaging agents can be used to non-invasively visualize and quantify their pharmacokinetic properties and biodistribution, enabling systematic studies on nanomedicine-based drug delivery to pathological sites. (B) Prototypic poly(HPMA)-based drug carriers of varying molecular weights were radiolabeled with ¹³¹I, showing that higher molecular weight polymers circulate for longer periods of time and accumulate better in subcutaneous Dunning AT1 prostate carcinoma tumors implanted in the lower right leg of rats. (C) Qualitative SPECT/CT image in xenograft bearing mice showing that at 48 h p.i., ¹¹¹In labeled PSMA targeted nanoparticle (TNP) accumulate in both PC-3 PIP, i.e. PSMA-positive (red circles) and PC-3 flu, i.e. PSMA-negative (yellow circles) tumors, while relatively low accumulation is observed for untargeted nanoparticle (UNP). Quantitative analysis shows better tumor retention of TNP than UNP at later time points, i.e. at 96 h p.i. (D) PET scans of a metastatic breast cancer patient showing that i.v. administered ⁶⁴Cu-labeled HER2-targeted liposomes circulate in the bloodstream and eventually accumulate in the RES organs liver and spleen, as well as in a metastatic bone lesion. Images reproduced, with permission, from ²³,³⁰,³¹.