CiteULike: xtizons spio

<I>In vivo</I> MRI using positive-contrast techniques in detection of cells labeled with superparamagnetic iron oxide nanoparticles

Wei Liu — 2007-08-21T12:06:29-00:00

NMR in Biomedicine, Vol. 9999, No. 9999. (2007), n/a.

Positive-contrast techniques are being developed to increase the detection of magnetically labeled cells in tissues. We evaluated a post-processing positive-contrast technique, susceptibility-gradient mapping (SGM), and compared this approach with two pulse sequences, a gradient-compensation-based ?White Marker? technique and an off-resonance-based approach, inversion recovery on-resonance water suppression (IRON), for the detection of superparamagnetic iron oxide (SPIO) nanoparticle-labeled C6 glioma cells implanted in the flanks of nude rats. The SGM, White Marker and IRON positive-contrast images were acquired when the labeled C6 glioma tumors were ?5 mm (small), ?10 mm (medium) and ?20 mm (large) in diameter along the largest dimension to evaluate their sensitivity to the dilution of the SPIO nanoparticles as the tumor cells proliferated. In vivo MRI demonstrated that all three positive-contrast techniques can produce hyperintensities in areas around the labeled flank tumors against a dark background. The number of positive voxels detected around small and medium tumors was significantly greater with the SGM technique than with the White Marker and IRON techniques. For large tumors, the SGM resulted in a similar number of positive voxels to the White Marker technique, and the IRON approach failed to generate positive-contrast images with a 200 Hz suppression band. This study also reveals that hemorrhage appears as hyperintensities on positive-contrast images and may interfere with the detection of SPIO-labeled cells. Published in 2007 by John Wiley & Sons, Ltd.

Recent advances in iron oxide nanocrystal technology for medical imaging

Claire Corot — 2007-08-02T08:54:44-00:00

Advanced Drug Delivery Reviews, Vol. 58, No. 14. (1 December 2006), pp. 1471-1504.

Superparamagnetic iron oxide particles (SPIO and USPIO) have a variety of applications in molecular and cellular imaging. Most of the recent research has concerned cellular imaging with imaging of in vivo macrophage activity. According to the iron oxide nanoparticle composition and size which influence their biodistribution, several clinical applications are possible: detection liver metastases, metastatic lymph nodes, inflammatory and/or degenerative diseases. USPIO are investigated as blood pool agents with T1 weighted sequence for angiography, tumour permeability and tumour blood volume or steady-state cerebral blood volume and vessel size index measurements using T2* weighted sequences. Stem cell migration and immune cell trafficking, as well as targeted iron oxide nanoparticles for molecular imaging studies, are at the stage of proof of concept, mainly in animal models.

Quantification of superparamagnetic iron oxide (SPIO)-labeled cells using MRI

Ali Rad — 2007-07-26T12:12:29-00:00

Journal of Magnetic Resonance Imaging, Vol. 26, No. 2. (2007), pp. 366-374.

To show the feasibility of using magnetic resonance imaging (MRI) to quantify superparamagnetic iron oxide (SPIO)-labeled cells.Lymphocytes and 9L rat gliosarcoma cells were labeled with ferumoxides-protamine sulfate complex (FE-PRO). The cells were labeled efficiently (more than 95%) and the iron concentration inside each cell was measured by spectrophotometry (4.77-30.21 pg). Phantom tubes containing different numbers of labeled or unlabeled cells, as well as different concentrations of FE-PRO, were made. In addition, labeled and unlabeled cells were injected into fresh and fixed rat brains.Cellular viability and proliferation of labeled and unlabeled cells were shown to be similar. T2-weighted images were acquired using 7T and 3T MRI systems, and R2 maps of the tubes containing cells, free FE-PRO, and brains were made. There was a strong linear correlation between R2 values and labeled cell numbers, but the regression lines were different for the lymphocytes and gliosarcoma cells. Similarly, there was strong correlation between R2 values and free iron. However, free iron had higher R2 values than the labeled cells for the same concentration of iron.Our data indicate that in vivo quantification of labeled cells can be done by careful consideration of different factors and specific control groups. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.