Evaluation of the effects of gold nanoparticle shape and size on contrast enhancement in radiological imaging

Abstract

There has been increasing interest in the use of a nanoparticle-based media as a contrast-enhancement agent in medical imaging, particularly with gold Nanoparticles in radiography. Particularly attractive, is the prospect of modifying the surface of these materials with monoclonal antibodies to preferentially bind the nanoparticles to tumour sites. These materials differ from conventional molecular agents in their ability to be modified with cell specificity, or tailored for size and shape for maximum uptake. We investigated the consideration that quantum confinement electronic effects in nanometre-sized metals might have an effect on the integrated photon attenuation of gold atoms; in the same manner as these materials affect X-ray absorption and scattering as seen in X-ray absorption spectroscopy. This experiment has been designed to identify any effect on contrast enhancement that might result from employing gold nanoparticles with a variety of sizes. Spherical particles and nanorods were synthesised for this application. Image contrast enhancement was quantified by contrast-to-noise ratio in computed radiography. Results are consistent with existing measurements of gold nanoparticle contrast enhancement in radiography. No significant variation in attenuation depending on particle size was observed. Findings indicate that nanoparticle-based contrast agents in the size range 4-30 nm-can be synthesised for maximum stability or cell specificity (directed cellular uptake) without consideration of effect of size on contrast enhancement.

Gold Nanoparticles as Contrast Agents in x-ray Imaging and Computed Tomography

“…Initial reports presented conflicting data, with one showing that the x-ray attenuation exhibited by smaller AuNPs (4 nm) was greater than larger particles (20, 40 and 60 nm) at the same concentration [36], and another showing no difference in x-ray attenuation between AuNPs of various sizes or shapes (spheres of ∼4, 6 and 25 nm, and rods of ∼30 nm diameter and ∼63 nm length) [84]. However, a recent report proved that x-ray attenuation is not influenced by AuNP size [32] by directly comparing the x-ray attenuation of AuNPs over a wide range of mean particle diameters (5, 13, 35 and 76 nm), including aqueous solutions of chloroauric acid com- Figure 5).…”

Characterisation of micro-sized and nano-sized tungsten oxide-epoxy composites for radiation shielding of diagnostic X-rays

“…Hitherto, numerous analytical methods have been developed to investigate the effect of the particle size of a material on the X-ray attenuation for various incoming X-ray energies including scattered gammarays and X-rays [1][2][3][4][5][6][7][8][9][10][11]. It is widely believed that nano-sized particles are able to disperse more uniformly within the matrix with less agglomerations when compared to micro-sized particles, thus improving the Xray attenuation ability of the material [6,12,13].…”

High-Resolution CT for Small-Animal Imaging Research

“…The advances in synthesizing nanoparticle contrast agents (Hainfeld et al, 2006;Jackson et al, 2011;Mukundan et al, 2006;Rabin et al, 2006) have enabled high-resolution rodent studies using micro-CT. As imaging probes, these nanoparticlebased contrast agents have also opened the door for molecular CT imaging using various targeting strategies (Chanda et al, 2011;Cormode et al, 2010;Ghann et al, 2012;Popovtzer et al, 2008;Reuveni, 2011;Wyss et al, 2009). A liposomaliodinated (Lip-I) contrast agent has been used to image the tumor microenvironment with exquisite detail (Ghaghada et al, 2011;Moding et al, 2012).…”