Papers by Keyword: Contrast Agent

Abstract: A magnetic resonance imaging contrast agent is proposed using iron oxide nanoparticles (IONPs) synthesized by a pulsed laser ablation technique. Experimentally, an Nd: YAG laser (1064 nm, 7 ns, 30 mJ) was directed and focused on a high-purity iron plate immersed in a liquid solution of deionized water and polyvinylpyrrolidone (PVP). After a few minutes of laser bombardment, iron oxide nanoparticles dispersed in the liquid were homogeneously produced. A reddish yellow color-colloidal IONPs are produced in the water, while its color changes to dark brown for the PVP solution. The characterization results demonstrated that IONPs in the form of Fe₂O₃ and Fe₃O₄ made in the PVP have an excellent dispersibility with a spherical shape that is significantly smaller than that of IONPs made in the deionized water at the same laser repetition rate. The produced IONPs are further applied as a contrast agent for the magnetic resonance imaging (MRI) modality by varying concentrations from 0.05 mM to 2.31 mM. The results demonstrated that images of the IONPs sample with a concentration of 2.31 mM showed the highest contrast enhancement (Cenh), with an enhancement factor of 221.875 % for T₁-weighted images and 91.227 % for T₂-weighted images. IONPs with a concentration of 2.31 mM had the highest signal-to-noise ratio (SNR) for a T₁-weighted picture of 52.92, while IONPs with a concentration of 0.05 mM had the highest SNR for a T₂-weighted image of 179.117.

Abstract: Development of body imaging techniques for medical diagnosis has future promising. To improve the image visibility, Gadolinium (Gd) has been known as an important material for preparing the contrast agent. However, since the rare earth metals have unique physical properties, the separation of Gd from the other metals by a simple, effective and efficient method is still challenging. Hereby, we report the separation of Gd from the rare earth mixture with dihexyl dithiophosphate (DHDTP) ligand by solvent extraction method. The amount of Gd before and after the extraction process was determined with ICP-OES. The results show that the extraction efficiency for the mixed samples of Gd (III) and Sm (III) is 53.10% with 51.10% purity of Gd (III) and extraction efficiency for mixed samples of Gd (III) and Dy (III) is 93.82% with 50.35% purity of Gd (III). This result indicates that DHDTP can be used for solvent extraction of Gd.

Abstract: Superparamagnetic Iron oxide nanoparticles (SPIONs) have fascinated researchers due to their vast applications in biomedical fields such as magnetic resonance imaging, cell sorting, hyperthermia, drug delivery etc. The special properties of SPIONs depend on the method of synthesis and surface modification. Among various synthetic protocols, hydrothermal method has attracted much attention due to simplicity, uniformity and excellent magnetic properties of iron oxide nanoparticles. Magnetic properties of SPIONs could be tuned by controlling the size and shape of the particles as well as by the surface modification. Low colloidal stability and high hydrophobic nature of SPIONs result in aggregation of the particles which could be avoided by surface modification of the SPIONs using various capping agents. The size, shape and surface environment of SPIONs can also be controlled by the surface coating. SPIONs are promising contrast agents due to their non-poisonous nature, biocompatibility and large surface area. The biocompatibility of SPIONs is enhanced by the surface coating/modification. The present review focuses on the hydrothermal synthesis of SPIONs and their characterization using various techniques and the applications of SPIONs in the MRI.Table of Contents

Abstract: In this paper, we proposed a novel texture preserving optical flow technique to estimate the motion patterns of contrast agent on the ultrasound image. The proposed method estimated the motion fields based on three major steps. Firstly, the proposed method recomposed the original image based on the weighted structure-texture decomposition. Secondly, we applied a slightly non-convex approximation approach by utilizing the spline interpolation based coarse-to-fine warping scheme to handle the motion discontinuities in ultrasound image. Lastly, after each warping step, we employed the bilateral filter into the numerical framework to minimize the tracking errors in motion estimates. To evaluate the tracking performance of our method, we estimated the motion fields of microbubbles for the tissue mimicking phantom, and compared its results to those of the existing methods. As a result, it was found that the proposed technique provides the most reliable motion patterns of microbubbles, and reduces computational loads, simultaneously. We also confirmed the potential usefulness of our estimation scheme for the microbubble based diagnostic analysis.

Abstract: The aim of the present study is to demonstrate some opportunities in targeted drug delivery using nanotechnology and nanomaterials. We report here the successful development of a contrast agent and media for hypothermal processes using our own synthetic method for SPIO nanoparticles and a cyclodextrin coating