Two optical coherence tomography systems detect topical gold nanoshells in hair follicles, sweat ducts and measure epidermis

Abstract

Optical coherence tomography (OCT) is an established imaging technology for in vivo skin investigation. Topical application of gold nanoshells (GNS) provides contrast enhancement in OCT by generating a strong hyperreflective signal from hair follicles and sweat glands, which are the natural skin openings. This study explores the utility of 150 nm diameter GNS as contrast agent for OCT imaging. GNS was massaged into skin and examined in four skin areas of 11 healthy volunteers. A commercial OCT system and a prototype with 3 μm resolution (UHR-OCT) were employed to detect potential benefits of increased resolution and variability in intensity generated by the GNS. In both OCT-systems GNS enhanced contrast from hair follicles and sweat ducts. Highest average penetration depth of GNS was in armpit 0.64 mm ± SD 0.17, maximum penetration depth was 1.20 mm in hair follicles and 15 to 40 μm in sweat ducts. Pixel intensity generated from GNS in hair follicles was significantly higher in UHR-OCT images (P = .002) and epidermal thickness significantly lower 0.14 vs 0.16 mm (P = .027). This study suggests that GNSs are interesting candidates for increasing sensitivity in OCT diagnosis of hair and sweat gland disorders and demonstrates that choice of OCT systems influences results.

Vascular morphology in normal skin studied with dynamic optical coherence tomography

“…This may be due to the location of hair follicles, which are surrounded by vessels in a dense network . The hair follicle has been examined in other OCT systems; however, our results indicate that D‐OCT may visualize the hair follicle in terms of its surrounding vessels as a “mottled” pattern with a “clustered” distribution, see Figure (E).…”

Optimized skin optical clearing for optical coherence tomography monitoring of encapsulated drug delivery through the hair follicles

“…due to differences in the values of the refractive index of calcium carbonate (1.6) and dermis (1.4). It is in a good agreement with the results presented in References , in which gold and TiO 2 nanoparticles have been used as contrast agents for hair OCT‐imaging. It is well seen in Figure D that in general level of OCT‐signal after TOC has been increased.…”

Potential of contrast agents to enhance in vivo confocal microscopy and optical coherence tomography in dermatology: A review

“…Recently, Mogensen et al suggested a potential for GNS in diagnosing skin diseases confined to adnexal structures. Hence, GNS may potentially allow novel insight into skin diseases where adnexal structures play a role in the pathogenesis e.g.…”

“…Although utilization of contrast agents for optical imaging is an evolving field in dermatology, the method has not yet gained substantial clinical impact. Indeed, application of contrast agents prior to optical imaging, such as gold nanoparticles or fluorescent dyes such as indocyanine green (ICG) appear to have potential for generating strong contrast signals in skin, thus potentially enhancing diagnostic accuracy of optical imaging devices at the bedside .…”