An Overview of Three Promising Mechanical, Optical, and Biochemical Engineering Approaches to Improve Selective Photothermolysis of Refractory Port Wine Stains

Abstract

During the last three decades, several laser systems, ancillary technologies, and treatment modalities have been developed for the treatment of port wine stains (PWSs). However, approximately half of the PWS patient population responds suboptimally to laser treatment. Consequently, novel treatment modalities and therapeutic techniques/strategies are required to improve PWS treatment efficacy. This overview therefore focuses on three distinct experimental approaches for the optimization of PWS laser treatment. The approaches are addressed from the perspective of mechanical engineering (the use of local hypobaric pressure to induce vasodilation in the laser-irradiated dermal microcirculation), optical engineering (laser-speckle imaging of post-treatment flow in laser-treated PWS skin), and biochemical engineering (light- and heat-activatable liposomal drug delivery systems to enhance the extent of post-irradiation vascular occlusion).

Vascular anomalies: classification, imaging characteristics and implications for interventional radiology treatment approaches

“…These variables reduce optical penetration depth and fluency, thereby reducing energy transfer to levels below those needed for coagulation. 26 To mitigate these factors, new techniques, including vacuumassisted laser therapy 27 and epidermal cooling, 28,29 have been developed. Although these techniques utilize different mechanisms, all serve to improve light delivery to the CM, thus increasing the temperature within the vessels to augment coagulation.…”

Quantitative assessment of graded burn wounds in a porcine model using spatial frequency domain imaging (SFDI) and laser speckle imaging (LSI)

“…A laser speckle pattern was generated by the 633nm laser source and projected onto the region of interest. This raw laser speckle image was then recorded with the CCD camera and processed on the computer using custom LabVIEW (Version 8.0, National Instruments, Austin, TX) software, integrating CUDA GPU code to carry out real-time LSI imaging and processing at a rate of eight frames per second [35,36]. The processed speckle image provides a blood flow map for the region of interest.…”

“…The processed speckle image provides a blood flow map for the region of interest. Blood flow is quantified by a metric known as Speckle Flow Index (SFI), which we have described previously [36]. Regions in which SFI values are high correspond to high blood flow and regions in which SFI values are low indicated areas of low blood flow.…”

Determination of pulse energy dependence for skin denaturation from 585nm fibre laser

“…In PWS, Selective Photothermolysis (SP) is a non-invasive laser treatment that relies on the conversion of radiant energy into heat causing an irreversible thermal damage [2]. According with the theory of SP, laser wavelength, pulse duration of laser and laser energy have to be considered.…”

“…PWS is characterized by high blood content in hyperdilated blood vessels [2] which are responsible to affect the surface of the skin giving the main characteristic of red color [3]. Other characteristic in PWS is the diameter of the blood vessels.…”