The aim is to demonstrate dynamic in-vivo tracking in real time of adoptively transferred CAR T cells for the treatment of solid tumors. Cells were labelled with novel Cu-64 labelled superparamagnetic iron oxide nanoparticles (SPION) and tracked using clinical grade dual PET-MR. Cu-64 radioisotope was bound to silica coated SPION using electrolysis plating with tin and palladium seeding. Cellular uptake of Cu-64 SPION was facilitated by a transfecting agent. Functional assays including 51Chromium release, cytometric bead array demonstrated that labelling process did not affect cytotoxicity and cytokine secretion (TNFα & IFN-g). Patients are being enrolled for a first in human in-vivo study to determine how many CAR T cells distribute to solid tumor sites within the first few days. Our results demonstrate that both fresh (N =3) and cryopreserved (N =3) CAR-T cells can be efficiently labelled in the range of 40% - 80% with high cell viability (≥90%). SUV mean trend provides insight into individual responses to therapy. Early time points showed moderate uptake of labelled cells in lungs posterior basal segments without increased activity over next few days, suggesting a transient process. Mild, diffuse bone marrow & relatively intense uptake of labelled cells in liver & spleen suggests margination of cells to reticulo-endothelial system. Excretion via hepatobiliary indicated reabsorption from GI tract and re-circulation of labelled cells. Minimal uptake in brain & heart supported safety profile of labeling agent. Labelled cells trafficked to various body organs in first few hours of infusion and remain persistent for up to 10-15 days.