To evaluate the capacity of human monocytes to phagocytose various approved iron oxide based magnetic resonance (MR) contrast agents and to optimize in vitro labeling of these cells. Human monocytes were incubated with two superparamagnetic iron oxide particles (SPIO) as well as two ultrasmall SPIO (USPIO) at varying iron oxide concentrations and incubation times. Iron uptake in monocytes was proven by histology, quantified by atomic emission absorption spectrometry and depicted with T2* weighted fast field echo (FFE) MR images at 1.5 T. Additionally, induction of apoptosis in iron oxide labeled monocytes was determined by YO-PRO-1 staining. Cellular iron uptake was significantly (P<0.01) higher after incubation with SPIO compared with USPIO. For SPIO, the iron oxide uptake was significantly (P<0.01) higher after incubation with the ionic Ferucarbotran as compared with the non-ionic Ferumoxides. Efficient cell labeling was achieved after incubation with Ferucarbotran at concentrations > or = 500 microg Fe/ml and incubation times > or = 1 h, resulting in a maximal iron oxide uptake of up to 50 pg Fe/cell without impairment of cell viability. In vitro labeling of human monocytes for MR imaging is most effectively obtained with the approved SPIO Ferucarbotran. Potential subsequent in vivo cell tracking applications comprise, e.g. specific targeting of inflammatory processes.

In a pilot study, we introduce fast handheld multispectral optoacoustic tomography (MSOT) of the breast at 28 wavelengths, aiming to identify high-resolution optoacoustic (photoacoustic) patterns of breast cancer and noncancerous breast tissue. We imaged 10 female patients ages 48-81 years with malignant nonspecific breast cancer or invasive lobular carcinoma. Three healthy volunteers ages 31-36 years were also imaged. Fast-MSOT was based on unique single-frame-per-pulse (SFPP) image acquisition employed to improve the accuracy of spectral differentiation over using a small number of wavelengths. Breast tissue was illuminated at the 700-970 nm spectral range over 0.56 seconds total scan time. MSOT data were guided by ultrasonography and X-ray mammography or MRI. The extended spectral range allowed the computation of oxygenated hemoglobin (HBO), deoxygenated hemoglobin (HB), total blood volume (TBV), lipid, and water contributions, allowing first insights into high-resolution breast tissue MSOT cancer patterns. TBV and Hb/HBO images resolved marked differences between cancer and control tissue, manifested as a vessel-rich tumor periphery with highly heterogeneous spatial appearance compared with healthy tissue. We observe significant TBV variations between different tumors and between tumors over healthy tissues. Water and fat lipid layers appear disrupted in cancer versus healthy tissue; however, offer weaker contrast compared with TBV images. In contrast to optical methods, MSOT resolves physiologic cancer features with high resolution and revealed patterns not offered by other radiologic modalities. The new features relate to personalized and precision medicine potential. .

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The in vivo distribution of intravenously administered iron oxide-labeled hematopoietic progenitor cells can be monitored with 1.5-T MR imaging equipment.