Mechanical tissue optical clearing devices: Enhancement of light penetration in ex vivo porcine skin and adipose tissue

Abstract

Background and Objective The complex morphological structure of tissue and associated variations in the indices of refraction of components therein, provides a highly scattering medium for visible and near‐infrared wavelengths of light. Tissue optical clearing permits delivery of light deeper into tissue, potentially improving the capabilities of various light‐based therapeutic techniques, such as adipose tissue removal or reshaping. Study Design/Materials and Methods We report results of a study to evaluate effectiveness of novel mechanical tissue optical clearing devices (TOCD) using white light photography and infrared imaging radiometry (IIR). The TOCD consists of a pin array and vacuum pressure source applied directly to the skin surface. IIR images recorded light absorption and temperature increase of ex vivo porcine skin and adipose during laser irradiation (980 and 1,210 nm) before and after TOCD application. Results White light photographic images of in vivo human skin demonstrated localized compression and altered visual appearance, indicative of water and blood movement in skin. White light photographic images also showed increased visible light transport through regions of ex vivo porcine skin compressed by TOCD pins. Rate of heating in sub‐dermal adipose regions beneath TOCD pins was twofold higher following TOCD application. Conclusions Results of our study suggest that mechanical optical clearing may provide a means to deliver increased light fluence to dermal and adipose tissues. Lasers Surg. Med. 40:688–694, 2008. © 2008 Wiley‐Liss, Inc.

Optical clearing of biological tissues: prospects of application in medical diagnostics and phototherapy

“…This model is sufficient to present the composition and mechanical properties of the skin well enough [196,201]. Basing on this model the authors of Ref.…”

“…However, at low concentrations OCAs do not provide sufficient optical clearing, while at high concentrations they can induce edema, chemical burn, partial necrosis and scarring [45,65,108]. To develop an efficient and safe way of breaking the integrity of the epidermis stratum corneum and accelerating the penetration of OCA into the dermis, various physical methods [56,118,[130][131][132][133][134][135][136][137][138][139][140], chemical enhancers of permeability [114,118,[141][142][143][144][145][146][147], and their combinations [118,148,149] have been proposed.…”

“…The method of compression optical clearing of tissues is implemented instrumentally (tissue optical clearing device, TOCD) [29,31,[194][195][196].…”

“…The effect of water transport was studied by Rylander et al [196]. In the skin the natural gradient of water content depending on the depth exists.…”

“…However, the multiple scattering essentially worsens the OCT imaging characteristics, namely, the image resolution, probing depth, and the precision of localisation [21]. In this connection the progress of optical clearing techniques is of huge potentiality for noninvasive OCT medical diagnostics [28,29,35,36,39,190,192,196].…”