Search

Purpose To demonstrate a new MR imaging approach that unambiguously identifies and quantitates contrast agents based on intrinsic agent properties such as r1 , r2 , r2*, and magnetic susceptibility. The approach is referred to as magnetic barcode imaging (MBI). Methods Targeted and bioresponsive contrast agents were imaged in agarose phantoms to generate T1 , T2 , T2*, and quantitative susceptibility maps. The parameter maps were processed by a machine learning algorithm that is trained to recognize the contrast agents based on these parameters. The output is a quantitative map of contrast agent concentration, identity, and functional state. Results MBI allowed the quantitative interpretation of intensities, removed confounding backgrounds, enabled contrast agent multiplexing, and unambiguously detected the activation and binding states of bioresponsive and targeted contrast agents. Conclusion MBI has the potential to overcome significant limitations in the interpretation, quantitation, and multiplexing of contrast enhancement by MR imaging probes. Magn Reson Med 77:970-978, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

To demonstrate a new MR imaging approach that unambiguously identifies and quantitates contrast agents based on intrinsic agent properties such as rTargeted and bioresponsive contrast agents were imaged in agarose phantoms to generate TMBI allowed the quantitative interpretation of intensities, removed confounding backgrounds, enabled contrast agent multiplexing, and unambiguously detected the activation and binding states of bioresponsive and targeted contrast agents.MBI has the potential to overcome significant limitations in the interpretation, quantitation, and multiplexing of contrast enhancement by MR imaging probes. Magn Reson Med 77:970-978, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Biocompatible Fe3O4 magnetic nanocrystals with reactive moieties on the surface can be prepared via a "one-pot" reaction and used straightforwardly in cancer detection by being coupled with a specific cancer-targeting antibody. It is demonstrated that the as-prepared Fe3O4 nanocrystals can potentially be used as effective magnetic resonance imaging (MRI) contrast agents for cancer diagnosis (see figure).

A one-pot reaction process was developed to synthesize highly dispersible, superparamagnetic Fe(3)O(4) nanoflowers; the potential of these nanoflowers as MRI contrast agents was investigated.

Magnetic resonance imaging (MRI) yields high spatially resolved contrast with anatomical details for diagnosis, deeper penetration depth and rapid 3D scanning. To improve imaging sensitivity, adding contrast agents accelerates the relaxation rate of water molecules, thereby greatly increasing the contrast between specific issues or organs of interest. Currently, the majority of T(1) contrast agents are paramagnetic molecular complexes, typically Gd(iii) chelates. Various nanoparticulate T(1) and T(1)/T(2) contrast agents have recently been investigated as novel agents possessing the advantages of both the T(1) contrast effect and nanostructural characteristics. In this minireview, we describe the recent progress of these inorganic nanoparticle-based MRI contrast agents. Specifically, we mainly report on Gd and Mn-based inorganic nanoparticles and ultrasmall iron oxide/ferrite nanoparticles.

The development of new types of high-performance nanoparticulate MR contrast agents with either positive (T(1)) or dual-contrast (both positive and negative, T(1) + T(2)) ability is of great importance. Here we report a facile synthesis of ultrasmall PEGylated iron oxide nanoparticles for dual-contrast T(1)- and T(2)-weighted MRI. The produced superparamagnetic iron oxide nanoparticles (SPIONs) are of high crystallinity and size uniformity with an average diameter of 5.4 nm, and can be individually dispersed in the physiological buffer with high stability. The SPIONs reveal an impressive saturation magnetization of 94 emu g(-1) Fe(3)O(4), the highest r(1) of 19.7 mM(-1) s(-1) and the lowest r(2)/r(1) ratio of 2.0 at 1.5 T reported so far for PEGylated iron oxide nanoparticles. T(1)- and T(2)-weighted MR images showed that the SPIONs could not only improve surrounding water proton signals in the T(1)-weighted image, but induce significant signal reduction in the T(2)-weighted image. The good contrast effect of the SPIONs as T(1) + T(2) dual-contrast agents might be due to its high magnetization, optimal nanoparticle size for T(1) + T(2) dual-contrast agents, high size monodispersity and excellent colloidal stability. In vitro cell experiments showed that the SPIONs have little effect on HeLa cell viability.

Magnetic resonance imaging (MRI) has become a powerful technique in biological molecular imaging and clinical diagnosis. With the rapid progress in nanoscale science and technology, nanostructure-based MR contrast agents are undergoing rapid development. This is in part due to the tuneable magnetic and cellular uptake properties, large surface area for conjugation and favourable biodistribution. In this review, we describe our recent progress in the development of high-performance nanostructured MR contrast agents. Specifically, we report on Gd-enriched nanostructured probes that exhibit T(1) MR contrast and superparamagnetic Fe(3)O(4) and CoFe(2)O(4) nanostructures that display T(2) MR contrast enhancement. The effects of nanostructure size, shape, assembly and surface modification on relaxivity are described. The potential of these contrast agents for in vitro and in vivo MR imaging with respect to colloidal stability under physiological conditions, biocompatibility, and surface functionality are also evaluated.