Abstract
In this work, we present a novel, simple, and highly accurate three-dimensional (3D) diffusion reflection (DR) imaging system and method for the detection of accumulation sites of gold nanorods (GNRs) within the tissue. GNRs are intensively used for diagnosis purposes of varied diseases, mainly because of their ability to well absorb visible light, which introduces them as terrific contrast agents in various imaging and theranostics methods. Lately, these GNRs unique absorption properties have served in DR intensity-based measurements, suggesting a novel diagnostic tool, DR-GNRs. In this paper, we show a new measurement system and method for DR, based on its radial collection from the tissue. These radial measurements enabled a unique 3D presentation of the DR-GNR, introducing the dimensions ρ for the radius, θ for the angle, and Γ for the reflected intensity. On the basis of the diffusion model, which enables to correlate between the sample's optical properties and its reflectance, a unique, radial map is presented. This map introduces the slopes of the DR curves in each measured angle, which are linearly correlated with the tissue's optical properties and with the GNRs concentrations within the tissue, thus enables the exact radial localization of the GNRs in the sample. We show the detection of macrophage accumulation in tissue-like phantoms, as well as the localization of unstable plaques in hyperlipidemic mice, in vivo. This highly accurate, powerful technology paves the way toward a real-time detection method that can be successfully integrated in the rapid increasing field of personalized medicine.