Whole-body diffusion-weighted imaging for staging malignant lymphoma in children

CT is currently the mainstay in staging malignant lymphoma in children, but the risk of second neoplasms due to ionizing radiation associated with CT is not negligible. Whole-body MRI techniques and whole-body diffusion-weighted imaging (DWI) in particular, may be a good radiation-free alternative to CT. DWI is characterized by high sensitivity for the detection of lesions and allows quantitative assessment of diffusion that may aid in the evaluation of malignant lymphomas. This article will review whole-body MRI techniques for staging malignant lymphoma with emphasis on whole-body DWI. Furthermore, future considerations and challenges in whole-body DWI will be discussed

Functionalized superparamagnetic iron oxide nanoparticles provide highly efficient iron-labelling in macrophages for magnetic resonance-based detection in vivo

Tracking cells during regenerative cytotherapy is crucial for monitoring their safety and efficacy. Macrophages are an emerging cell-based regenerative therapy for liver disease and can be readily labeled for medical imaging. A reliable, clinically applicable cell-tracking agent would be a powerful tool to study cell biodistribution.Using a recently described chemical design, we set out to functionalize, optimize and characterize a new set of superparamagnetic iron oxide nanoparticles (SPIONs) to efficiently label macrophages for magnetic resonance imaging-based cell tracking in vivo.A series of cell health and iron uptake assays determined that positively charged SPIONs (+16.8 mV) could safely label macrophages more efficiently than the formerly approved ferumoxide (-6.7 mV; Endorem) and at least 10 times more efficiently than the clinically approved SPION ferumoxytol (-24.2 mV; Rienso). An optimal labeling time of 4 h at 25 µg/mL was demonstrated to label macrophages of mouse and human origin without any adverse effects on cell viability whilst providing substantial iron uptake (>5 pg Fe/cell) that was retained for 7 days in vitro. SPION labeling caused no significant reduction in phagocytic activity and a shift toward a reversible M1-like phenotype in bone marrow-derived macrophages (BMDMs). Finally, we show that SPION-labeled BMDMs delivered via the hepatic portal vein to mice are localized in the hepatic parenchyma resulting in a 50% drop in T2* in the liver. Engraftment of exogenous cells was confirmed via immunohistochemistry up to 3 weeks posttransplantation.A positively charged dextran-coated SPION is a promising tool to noninvasively track hepatic macrophage localization for therapeutic monitoring