This PDF file contains the front matter associated with SPIE Proceedings Volume 10467, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Optical coherence tomography (OCT) has become a useful skin imaging tool in recent years. It can be used to image skin structure with great detail and deep below the surface. However, there is an unmet need for an inexpensive device that would be able to acquire high-quality en face images in short time. To this end, we report on a cost-effective full-field optical coherent tomography (FF-OCT) system comprised of a silicon camera with high full well capacity and a powerful near-infrared LED light source. The system, for example, is able to record 1.7 cm × 1.7 cm en face images in 0.12 sec with the spatial sampling rate of 2116 dpi and the sensitivity of 93 dB. We show that the FF-OCT system can be used for biometrics purposes by imaging internal fingerprints and sweat ducts with a good contrast and in short-enough time. Blood flow can also be sensed in dermis that, for example, can be used for liveness detection. The developed instrument could also be used in other en face deep-tissue imaging applications because of its high sensitivity and speed. One particular application is passive elastography that can map the stiffness of biological tissues. We will also present FF-OCT configurations that help improving the imaging depth through rejection of specular reflections and better use of a light budget.

Androgenic alopecia(AA), commonly known as pattern baldness, initially manifests as a receding or thinning hairline in men and women respectively. While the condition may be apparent at a later stage of development, it is routinely cumbersome to diagnose in its early stages. The current gold standard for AA diagnosis is trichoscopy of the scalp and the more invasive punch biopsy when trichoscopy yields insufficient insight towards the cause of hair loss. Trichoscopy, a magnified image of the scalp, can provide a superficial understanding of the hair diameter as well as scalp discoloration around the follicular opening. Histopathological analysis of hair follicles provides information such as hair follicle density, and the diameter of the hair shaft and follicle used to determine the extent of alopecia. Since the information provided by trichoscopy is somewhat limited and punch biopsies are invasive, physicians cannot properly assess multiple areas of the scalp to provide proper diagnosis of androgenic alopecia. Optical Coherence Tomography(OCT), a non-invasive, non-ionizing tomographic imaging technique, can rapidly provide near histopathological cross sectional 3D images. This technique has been identified as a plausible candidate for in-vivo assessment of hair loss. Through this pilot study, we have prospectively enrolled eight patients undergoing varying degrees of hair loss to assess the efficacy of OCT to detect differences in hair shaft and follicle anatomy. Our preliminary results show the capability of OCT to non-invasively resolve hair follicle density, hair shaft and follicle diameters between patients at varying stages of hair loss.

The human skin is comprised by two layers; epidermis and dermis, separated by the dermo-epidermal junction (DEJ). The relevance of depicting DEJ and measurement of the epidermal thickness (ET) is e.g. seen for superficial skin cancers where delineation of DEJ is of prime prognostic importance. Another example is diagnosis of psoriasis where a thickened epidermis and a ridged DEJ is a hallmark. Histopathological examination of biopsied tissue is traditionally performed to trace DEJ and measure ET. An efficient and precise method to locate DEJ and measure ET is optical coherence tomography (OCT) which is an in vivo and non-invasive technique. Because of significant changes in the refractive index across the DEJ, it is generally easily resolvable with OCT. However at certain body locations, such as the cheek and in regions of glabrous skin, it is difficult to visualize DEJ since refractive index changes are small. We study the significance of ultrahigh resolution OCT combined with a shadow compensation algorithm in locating the DEJ of the cheek and the palm of the hand of ten healthy volunteers. For the study we use a home-built ultrahigh resolution OCT system and a commercially available OCT system designed for dermatology diagnostic. With this comparative study we conclude on the signal statistics of both dermis and epidermis for the two OCT systems and how the differences of these affect the delineation of DEJ. We finally conclude on the significance of ultrahigh resolution OCT in detecting DEJ and measuring ET.

The ability to image the physiology of microvasculature with high spatial resolution in three dimensions while investigating structural changes of skin, is essential for understanding the complex processes of skin aging, wound healing and disease development. Further, the quantitative, automatic assessment of these changes enables to analyze large amounts of image data in an abstract but comprehensive manner. However, previous work using OCT with methods of angiography was imaging less scattering, hence more challenging tissue than skin, such as brain and retina tissue. The published methods for capillary segmentation were mostly non-automatic, poorly benchmarked against state-of-the-art methods of computer vision and not applied to investigate medical processes and studies in a comprehensive fashion. Here, segmentation of capillaries in skin is reported and its efficacy is demonstrated in both, a longitudinal mouse study and a preliminary study in humans. By combining state-of-the-art image processing methods in an optimized way, we were able to improve the segmentation results and analyze the impact of each post-processing step. Furthermore, this automatic segmentation enabled us to analyze big amounts of datasets automatically and derive meaningful conclusions for the planning of clinical studies. With this work, optical coherence tomography is combined with methods of computer vision to a diagnostic tool with unique capabilities to characterize vascular diversity and provide extraordinary opportunities for dermatological investigation in both, clinics and research.

Optical coherence tomography (OCT) has been used for visualization of morphological change of tissues over time. Although current OCT technology allows the volumetric and high throughput information of tissues, its quantification and analysis still uses time inefficient and tedious process. In order to fully utilize benefits of OCT, it is desired to integrate the intelligent software platform. As deep learning technology is advanced, it has been emerged as the alternative way for quantitative and automated image processing in bio-imaging field including optical imaging. Deep leaning technique is based on the sufficient training data which could overcome the drawback of traditional handcrafted optical image processing algorithms. In this study, we introduce a novel and intelligent OCT software platform for accurate skin analysis and classification using deep learning module. Our platform is equipped with automated calculations of morphological skin parameters, such as surface roughness, wrinkle depth, volume, and epidermal thickness. To date, most promising tool for quantitative skin analysis is to use a software package of PRIMOS device which relies on three-dimensional camera systems. In order to evaluate our software platform, we compared OCT skin parameters based on deep learning technique and conventional PRIMOS data. Our preliminary study shows that proposed software platform for 3D OCT is a promising tool for accurate, efficient, and quantitative analysis of volumetric skin. It could be also a better alternative than existing PRIMOS solutions to both cosmeceutical and dermatological field.

In the past reports, excessive or long-term ultraviolet (UV) irradiation may cause DNA damage, resulting in genetic mutations and probably leading to skin cancer. However, it is difficult to noninvasively diagnose skin damage in the early stage due to excessive and long-term UV exposures. In this study, we propose to use optical coherence tomography (OCT) for noninvasively investigating the progress of skin damage due to excessive UV irradiation. The developed OCT system can provide the ability of label-free 3D microstructural and microvascular imaging with the axial and transverse resolution of 7 and 5 m, respectively. Mouse skin is used as the experimental model and exposed to different UV exposure powers of 5, 20 and 50W (corresponding to the power densities of 1.6, 6.4, and 16 W/cm2) for various time periods. The results show that the morphological and microcirculation changes can be identified when the skin is exposed to different exposure powers. With a lower exposure power of 5 W, no significant structural change can be found from the OCT results, but the vessel sizes are slightly increased and the vessel density is also increased. When the exposure power of UV light is increased to 20 W, the vessel density is increased significantly with the exposure time and the structural damage is also can be found. Then, when mouse skin is exposed to a higher UV power of 50 W for 8 mins, the skin structure and vessels are severely damaged. Finally, the skin after the exposures of various UV powers is also followed up with OCT to evaluate the skin recovery. The results show that the structural and microvascular changes due to UV irradiation can be identified with OCT and OCT can be an effective and noninvasive diagnostic tool for the early-stage sun damage.

Currently, allergy testing is performed by exposing the skin to small quantities of potential allergens on the inner forearm thereby scratching the protective epidermis to increase exposure. After 15 minutes the dermatologist performs a visual check of the 'bump' induced by swelling and erythema. In this study, two high resolution 3D scanners (Artec Spider and EVA) were used to quantify the dimensions (circumference, surface area, thickness) of the bump and to assess which parameters correlate with the diagnosis of the dermatologist. For comparison and validation of the scanners and the analysis-software (Artec Studio and GOM Inspect), phantom 'bumps' were developed. In a small clinical feasibility study, data of 3 patients with 17 positive allergic reactions were obtained and analyzed with the optimum settings based on the phantom study. Although both scanners could differentiate between the reaction grade 1, 2 or 3 assigned by the dermatologist, the results were not significant due to the small number of reactions at this time of the study. Both in the phantom and clinical study, the Artec Spider 3D scanner showed the allergic reactions clearly but an practical method of analysis needs to be developed to grade them similar to dermatologists. The resolution of the Artec EVA 3D scanner is lower but this scanner is more practical for use in the clinic (fast and easy to use). 3D scanners have a great potential for quantitative imaging in dermatology and aesthetic surgery.

The current standard for assessment of burn severity and subsequent wound healing is through clinical examination, which is highly subjective. Accurate early assessment of burn severity is critical for dictating the course of wound management. Complicating matters is the fact that burn wounds are often large and can have multiple regions that vary in severity. In order to manage the treatment more effectively, a tool that can provide spatially resolved information related to mapping burn severity could aid clinicians when making decisions. Several new technologies focus on burn care in an attempt to help clinicians objectively determine burn severity. By quantifying perfusion, laser speckle imaging (LSI) has had success in categorizing burn wound severity at earlier time points than clinical assessment alone. Additionally, spatial frequency domain imaging (SFDI) is a new technique that can quantify the tissue structural damage associated with burns to achieve earlier categorization of burn severity. Here we compared the performance of a commercial LSI device (PeriCam PSI, Perimed Inc.), a SFDI device (Reflect RS^TM, Modulated Imaging Inc.) and conventional clinical assessment in a controlled (porcine) model of graded burn wound severity over the course of 28 days. Specifically we focused on the ability of each system to predict the spatial heterogeneity of the healed wound at 28 days, based on the images at an early time point. Spatial heterogeneity was defined by clinical assessment of distinct regions of healing on day 28. Across six pigs, 96 burn wounds (3 cm diameter) were created. Clinical assessment at day 28 indicated that 39 had appeared to heal in a heterogeneous manner. Clinical observation at day 1 found 35 / 39 (90%) to be spatially heterogeneous in terms of burn severity. The LSI system was able to detect spatial heterogeneity of burn severity in 14 / 39 (36%) cases on day 1 and 23 / 39 cases (59%) on day 7. By contrast the SFDI system was able to detect spatial heterogeneity of burn severity in 39 / 39 (100%) cases on day 1. Here we have demonstrated that for the purposes of predicting heterogeneity in wound healing, SFDI generated scattering properties were a significantly more effective tool than perfusion images measured using LSI. This indicates that SFDI may be better suited to help clinicians categorize different burns earlier, ultimately informing treatment strategy to improve patient outcomes.

Spatial frequency domain imaging (SFDI) utilizes a digital light processing (DLP) projector for illuminating turbid media with sinusoidal patterns. The tissue absorption (μ_a) and reduced scattering coefficient (μ^,_s) are calculated by analyzing the modulation transfer function for at least two spatial frequencies. We evaluated different illumination strategies with a red, green and blue light emitting diodes (LED) in the DLP, while imaging with a filter mosaic camera, XiSpec, with 16 different multi-wavelength sensitive pixels in the 470-630 nm wavelength range. Data were compared to SFDI by a multispectral camera setup (MSI) consisting of four cameras with bandpass filters centered at 475, 560, 580 and 650 nm. A pointwise system for comprehensive microcirculation analysis was used (EPOS) for comparison. A 5-min arterial occlusion and release protocol on the forearm of a Caucasian male with fair skin was analyzed by fitting the absorption spectra of the chromophores HbO₂, Hb and melanin to the estimatedμ_a. The tissue fractions of red blood cells (fRBC), melanin (/mel) and the Hb oxygenation (^S0₂ ) were calculated at baseline, end of occlusion, early after release and late after release. EPOS results showed a decrease in ^S0₂ during the occlusion and hyperemia during release (^S0₂ = 40%, 5%, 80% and 51%). The fRBC showed an increase during occlusion and release phases. The best MSI resemblance to the EPOS was for green LED illumination (^S0₂ = 53%, 9%, 82%, 65%). Several illumination and analysis strategies using the XiSpec gave un-physiological results (e.g. negative ^S0₂ ). XiSpec with green LED illumination gave the expected change in /RBC , while the dynamics in ^S0₂ were less than those for EPOS. These results may be explained by the calculation of modulation using an illumination and detector setup with a broad spectral transmission bandwidth, with considerable variation in μ_a of included chromophores. Approaches for either reducing the effective bandwidth of the XiSpec filters or by including their characteristic in a light transport model for SFDI modulation, are proposed.

The ability to predict success or failure of wound healing strategies in burns has the potential to enable customized treatments tailored for the individual patient that would ultimately shorten recovery times, reduce the need for repeated grafting, and aid in achieving full rehabilitation. To this end, we are investigating the potential for spatial frequency domain imaging (SFDI) to non-invasively assess wound severity and healing status. SFDI is a wide-field diffuse optical imaging technique that enables non-invasive quantitative determination of in vivo tissue optical properties associated with physiologic structure and function. We have employed SFDI in a longitudinal study of wound healing using a controlled porcine burn model. Regions of wound repair using split thickness skin grafts were imaged using SFDI at multiple time points over a period of 60 days. The reduced scattering and absorption coefficients were determined at nine wavelengths spanning 470–970 nm, enabling determination of oxy- and deoxy-hemoglobin concentration, total hemoglobin concentration, oxygen saturation, and water fraction. These values obtained were compared to unburned control regions, undebrided burns, and debrided regions without treatment by grafting. Changes in the reduced scattering associated with structural changes in tissue correlate with histology as the wound heals. Compared to unburned tissue, the reduced scattering coefficient associated with repaired wounds is depressed and is spatially heterogeneous immediately following grafting. Over the course of healing, the scattering values increase and converge toward values of normal tissue and become more spatially homogeneous. Variations in chromophore concentrations are also characterized.

Non-melanoma skin cancer is the most common cancer. On cosmetically sensitive areas, Mohs micrographic surgery is the standard of care; intra-operative margin assessment minimizes the surgical defect while helping to reduce the recurrence rate by a factor of 3 compared to surgical excision. The current Mohs technique relies on frozen section tissue slide preparation, which significantly lengthens operative time and requires on-site trained histotechnicians. Full-field micro-tomography is a novel optical imaging technique based on interferometry. It allows the extraction of a full-field optical coherence tomography (FFOCT) image, representative of the morphology of the tissue, and the dynamic cell information, representative of the intra-cellular metabolic activity. Both images are calculated at the micron-level in a few minutes and without tissue preparation. This multi-centric study aimed to evaluate these combined new imaging modalities for the analysis of skin cancer margins during Mohs surgery. Over 200 Mohs specimens were imaged in Drexel University College of Medicine, USA, and GHR Mulhouse Sud Alsace, France. An atlas was established of FFOCT images and corresponding histological slides to reveal FFOCT reading criteria of normal and cancerous structures. Dynamic cell information enhanced visualization of cancerous cells and surrounding immune cells, and yielded metabolic quantification of cancerous area versus benign areas. Finally, deep learning algorithms were developed for preliminary results for the automatic detection of cancerous tissue. Hybrid morphologic and metabolic micro-tomography techniques hold great potential for skin cancer margin assessment. They can potentially reduce recurrence rates and surgery times, optimize clinical workflow, and decrease healthcare costs.

Dermatoscopes are commonly utilized by medical professionals for the qualitative visual inspection of skin lesions. While automated image processing techniques and varied illumination strategies can aid in structural analysis of lesions, robust quantification of functional information is largely unknown. To address this knowledge gap, we have developed a compact, handheld dermatoscope that enables real-time blood flow measurements of skin using coherent illumination and laser speckle imaging (LSI). A second color camera attached to the dermatoscope helps with the simultaneous real-time observation of the skin lesions and allows the user to acquire and save color images via a custom Graphical User Interface. In-vitro characterization utilizing a blood flow phantom demonstrated that the dermatoscope is capable of quantifying changes in blood flow across a physiologically relevant range even when used in a handheld manner with ambient lighting. We also demonstrated that the dermatoscope can quantify blood flow in skin lesions in human subjects and that significant differences in blood flow are present among lesion types. There was significantly increased blood flow relative to the surrounding skin in cherry angiomas compared to solar lentigos (p<0.05), which was expected based on the vascular and pigment compositions of the two lesion types. Furthermore, we have compared blood flow maps collected from potentially cancerous lesions prior to histological analysis to determine whether blood flow measurements can help in the diagnosis of benign and malignant skin lesions. Information provided by the LSI dermatoscope may help with earlier and more accurate diagnoses of pigmented skin lesions.

Treatment and management of alopecia are highly determined by an accurate diagnosis, which can be challenging due to the lack of methods to properly visualize hair follicles. Current standard diagnosis is based on dermoscopy for non-scarring alopecia and scalp biopsy for scarring types of alopecia. Dermoscopy can be inconclusive, while biopsy is a painful procedure. In this study, we used a clinical tomograph based on multiphoton microscopy (MPM) to non-invasively image the scalp of 5 healthy subjects and of 12 patients affected by non-scarring alopecia (androgenetic and areata) and scarring alopecia (frontal fibrosing). MPM is capable of non-invasive in vivo imaging of follicular structures in human scalp including hair shafts, hair follicles and sebaceous glands via two-photon excited fluorescence (TPEF) from keratin and NADH/FAD and of the papillary dermis surrounding the hair follicles through second harmonic generation (SHG) from collagen and TPEF from elastin fibers. In normal and non-scarring alopecia patients, MPM often identified presence of sebaceous glands associated with hair follicles, while MPM images of scarring alopecia were characterized by miniaturization of hair follicles as well as by presence of macrophages and lymphocytes surrounding hair follicles. A quantitative analysis involving measurement of hair follicle diameter sizes showed they were significantly smaller in scarring comparing to non-scarring alopecia patients and to normal scalp subjects (p < 0.043). This study shows, in a limited number of patients, that MPM imaging can non-invasively identify morphological features that distinguish scarring from non-scarring alopecia.

Oral minocycline has been the standard of care for the treatment of non-nodular moderate to severe inflammatory acne vulgaris due to its inhibitory effects on the acne-causing Propionibacterium acnes bacterium and its anti-inflammatory properties, Despite the availability of an oral dosage form since 1966, a commercial topical minocycline remains elusive because of the challenges in stabilizing the active pharmaceutical ingredient (API) in a liquid/semisolid while ensuring sufficient uptake into targeted lesions. Recently, an investigative topical minocycline gel (BPX-01) has been developed to address the unmet needs for localized and targeted delivery while minimizing the risks of systemic side effects. Earlier preclinical studies pertaining to transepidermal delivery of the API had depended on semi-infinite doses of the 1%, 2% and 4% formulations to elicit enough fluorescence yield. We have subsequently shown evidence of minocycline delivery of 1% and 4% BPX-01 into the pilosebaceous unit of ex vivo human facial skin specimens dosed with about 2.5× daily dose using two-photon excitation fluorescence microscopy. In this study, we demonstrated another novel approach to identifying minocycline fluorescence signature using fluorescence lifetime imaging microscopy (FLIM) with phasor analysis. It was found that for a single daily dose and with FLIM, minocycline was consistently noted in the epidermis and hair follicle, with some incidence in the sebaceous gland for both 1% and 2% BPX-01. These observations corroborated with the recent success of a Phase 2b dose-finding study, with 2% BPX-01 meeting the primary endpoint of lesion reduction at week 12 with statistical significance over the vehicle.

Recent translation of multiphoton microscopy to clinical practice raises the possibility of high-resolution in-vivo histology of skin. This is of special interest for cancer diagnostics, because early stages of basal cell carcinomas (BCCs) and malignant melanomas (MM) can be imaged. The novel label-free non-invasive process, called multiphoton tomography (MPT), would reduce the time from consultation to treatment. MPT is a nonlinear laser scanning microscopy technique that features high three-dimensional resolution and label-free molecular contrast. Several endogenous tissue components can be visualized, including collagen (through second-harmonic generation), NAD(P)H, FAD, keratin, melanin, porphyrins, and elastin fibers (through two-photon excited fluorescence). Furthermore, fluorescence lifetime imaging (FLIM) can be employed to detect inflammation sites in patients suffering from dermatitis and chronic wounds. The add-on module CARS (Coherent Anti-Stokes Raman Spectroscopy) provides information on the lipid and water distribution. Multimodal MPT is performed in high-tech hospitals in Europe (e.g. Charité/Germany), China, Russia (e.g. Medical Academy, Nizhny Novgorod), Australia (e.g. Princess Alexandra Hospital, Brisbane) and United States (e.g. Beckman Laser Institute and Medical Clinic UCI, Irvine, and University of Illinois at Urbana-Champaign).

Autofluorescence, diffuse-reflectance and transmission spectral, and microscopic measurements were made on different cutaneous neoplastic lesions, namely basal cell carcinoma, squamous cell carcinoma, malignant melanoma, and dysplastic and benign lesions related. Spectroscopic measurements were made on ex vivo tissue samples, and confocal microscopy investigations were made on thin tissue slices.

Fluorescence spectra obtained reveal statistically significant differences between the different benign, dysplastic and malignant lesions by the level of emission intensity, as well by spectral shape, which are fingerprints applicable for differentiation algorithms. In reflectance mode the most significant differences are related to the influence of skin pigments – melanin and hemoglobin. Transmission spectroscopy mode gave complementary optical properties information about the tissue samples investigated to that one of reflectance and absorption spectroscopy.

Using autofluorescence detection of skin lesions we obtain very good diagnostic performance for distinguishing of nonmelanoma lesions. Using diffuse reflectance and transmission spectroscopy we obtain significant tool for pigmented pathologies differentiation, but it is a tool with moderate sensitivity for non-melanoma lesions detection. One could rapidly increase the diagnostic accuracy of the received combined “optical biopsy” method when several spectral detection techniques are applied in common algorithm for lesions’ differentiation.

Specific spectral features observed in each type of lesion investigated on micro and macro level would be presented and discussed. Correlation between the spectral data received and the microscopic features observed would be discussed in the report.

Combination of diffuse reflectance spectroscopy (DRS) and pulsed photothermal radiometry (PPTR) was recently successfully used to study evolution of accidental traumatic bruises. Yet, accidental bruises introduce many unknowns into the evolution analysis and thus a more controllable and repeatable approach for bruising is desired. In this study, evolution of bruises induced by aluminum projectiles of known mass and velocity were studied by DRS and PPTR. Bruises were induced on volar forearm skin of two healthy volunteers. Inverse Monte Carlo including four-layer skin model, was used to analyze the DRS and PPTR data to determine skin chromophores, their concentrations and depths. For bruise analysis, a bruise model was constructed and evolved according to hemoglobin diffusion kinetics. Bruise analysis of PPTR signals yielded bruise evolution parameters, most importantly hemoglobin diffusion constant, hemoglobin decomposition time and blood pool depth. The study results show that chronological tracking of hemoglobin decomposition can be assessed by the combined DRS and PPTR technique on induced bruise. Parameters of individual bruises were compared and two trends in chronological behavior of hemoglobin decomposition time discerned. Changes in bruise diffuse reflectance spectra were noted. Induced bruise parameters, however, still showed some scatter and thus further research is needed to reduce bruise variability.

Background and Objectives: UV Fluorescence Excitation Imaging (u-FEI) has been shown to be a simple but robust, non-invasive and non-contact method to visualize cells with a high proliferative rate. We had demonstrated the ability of u-FEI to visualize the re-epithelialization of skin wounds in an organ culture system. In this work, we investigated the potential of u-FEI for visualization of wound closure of partial and full-thickness skin wounds. Study Design: Partial and full-thickness skin wounds were created in the tail of rats. Wounds were imaged weekly using u-FEI system operating at 295/340nm excitation/emission wavelengths, which correspond to the excitation/emission bands of the endogenous fluorophore tryptophan. Histology and immunohistology were used to determine the association between fluorescence intensity and proliferation of keratinocyte cells. Results: Similar to human skin, the skin of a rat tail heals by re-epithelialization. Keratinocytes migrated and proliferated from the edge and skin appendages of partial-skin wounds to close the wound by creating neo-epidermis. The fluorescence intensity of the whole wound area increased uniformly during week one and decreased to non-wounded control levels around week three. For full-thickness wounds, keratinocytes migrated only from the wound edges as skin appendages were missing. The fluorescence intensity was higher by the wound edge and marched towards the center during healing. H&E and immunohistology show that changes in fluorescence intensity corresponded to newly formed epidermis. Conclusions: u-FEI of tryptophan allowed visualization of wound closure of partial and full-thickness skin wounds in an in vivo model of wound healing by epithelialization.

We show the feasibility of short wave infrared spectroscopy combined with tape stripping as a simple and noninvasive method for the analysis of lipids and the degree of hydration as a function of depth in the stratum corneum. The spectroscopic method utilizes differential detection with three wavelengths 1720, 1750, and 1770 nm, corresponding to the lipid vibrational bands that lay “in between” the prominent water absorption bands. The results are compared with other biophysical devices such as Corneometer and Sebumeter.

We use terahertz time domain imaging for the evaluation of the effects of skin-moisturizers in vivo. We evaluate three principal substances used in commercial moisturizers: glycerin, hyaluronic acid and lanolin. We image the interaction of the forearm with each of the substances taking terahertz spectra at sequential times. With this, we are able to measure the effect of the substances on the hydration level of the skin in time, determining the feasibility of using THz imaging for the evaluation of the products and their effects on the hydration levels of the skin.

Changes in the cellular homeostasis in response to a stimuli, disease or therapeutic intervention are multifaceted in nature, and cannot be grasped by routinely employed targeted imaging that focuses on a small set of suspected molecules or genes. Novel approaches relying on global analysis of cellular features, from morphology to the composite biomolecular status (notably chemical composition and molecular conformation), is a pre-requisite for accurate monitoring of cellular processes. In the present study label-free profiling of normal skin fibroblasts (Hs895.Sk) exposed to sub-lethal doses of ultra-violet radiation has been performed using quantitative phase imaging and Raman spectroscopy. Spectral differences in the Raman fingerprint region indicates differences in the protein and nucleic acid composition. These differences were successfully utilized to develop an automated classification model based on principal component analysis. Distinct changes in the cellular morphology were observed and validated through quantitative phase imaging. Significant dose dependent differences in different biophysical parameters such as dry mass and matter density were observed. Combination of these two techniques, one suited for detection of subtle morphological/biophysical alterations while the other appropriate for capturing molecular perturbations, could pave the way to address issues of label-free monitoring of cellular responses in response to an external stimulus. These findings can provide an accurate understanding of different markers associated with radiation damage and would assist in providing a quantitative tool to our future studies on designing alternate diagnostic tools.

Melanoma is the most aggressive type of skin cancer with high rates of recurrence, morbidly and mortality. Current standard treatment involves surgery, chemotherapy, immunotherapy and also radiation therapy but the response is limited to early-stage tumors. Photodynamic therapy (PDT) is already established as an effective therapeutic option for cutaneous pre-malignant lesions and non-melanoma skin cancer but has shown very limited efficacy for pigmented lesions as melanoma, where the high melanin absorption limits light penetration, preventing complete treatment. Optical clearing agents (OCA) are hyperosmotic agents that work by dehydrating tissue and matching the tissue refractive index, thereby reducing scattering and improving light penetration. here, OCA was used in combination with single and dual photosensitizer-based PDT, targeting the tumor cells and vasculature to improve treatment response in both melanotic and amelanotic melanoma models in vivo. Vascular-targeted PDT was more efficient for amelanotic tumors, independent of the use of OCA and could treat the whole tumor in a single treatment session. However, for the melanotic tumors, OCA significantly improved PDT response for the both vascular-targeted and dual-agent PDT. The best result was obtained with the latter, resulting in no tumor being detected by H&E staining and S100 immunostaining. These initial pre-clinical results show the potential use of dual agent PDT enhanced by OCA for the treatment of pigmented cutaneous melanoma.

Solar radiation has been accepted as a major contributor to the development of skin cancer. Recent studies have shown that visible light (VL), a major portion of solar spectrum, induces biologic effects. UV filters in currently available sunscreens do not offer protection against VL. Diffuse reflectance spectroscopy (DRS) is a noninvasive objective assessment technique. Previous studies have focused on physiological parameters including melanin concentration, hemoglobin concentration, scattering and oxygen saturation. However, the differential absorbance spectra, difference between absorbance spectra of irradiated site and adjacent un-irradiated skin, can aid in the identification of various phases of skin response after VL irradiation. We irradiated the back of 62 subjects with a VL source, which consisted of a halogen lamp with filters resulting in a spectral output with greater than 98% VL. Reflectance spectra was collected for VL irradiated sites (160 J/cm2 to 480 J/cm2) immediately post-irradiation, at 24 hours, and at 7 days post-irradiation. DRS aided in classifying skin responses in terms of clinical and sub-clinical erythema accompanied by pigmentation phases based on the corresponding spectral signatures. The response in terms of skin darkness was assessed by integrating the differential absorbance spectra between 400 and 700 nm (AUC, area under the curve) since it includes contribution from both melanin and hemoglobin. The findings demonstrate the potential of DRS in assessing photoprotection offered by a product against VL induced pigmentation and erythema, VL protection factor, which can be assessed by comparing the AUC of the protected skin to that of the unprotected skin.

The objective of this study was to investigate the feasibility of using optical polarization imaging (OPI) for the preoperative delineation of nonmelanoma skin cancer (NMSC) margins. OPI has been previously used for monitoring dermal collagen changes in healthy volunteers in vivo. Since the structure of normal collagen is disrupted in NMSCs, OPI should be capable of delineating skin cancer margins by identifying the disrupted collagen network. Patients with biopsy confirmed NMSCs were recruited under an IRB approved protocol. Prior to imaging, the lesion area was cleaned with alcohol and the intended boundaries of the excision were marked by the surgeon, who was blinded from the imaging results. The imager used narrow band linearly polarized light centered at 440 nm and 640 nm. Cross-polarized reflectance images acquired at 440 nm and 640 nm visualized dermal collagen and the blue marker used by the surgeon to outline the putative lesion boundaries, respectively. The imager provided a 4 cm2 field of view, 200-700µm imaging depth and the light power density at the skin surface of 0.38mW/cm2. Following imaging, routine Mohs procedure was performed using the original markings of the surgeon. After the surgery, images acquired by OPI were compared with the Mohs maps created based on histopathological analysis. Our results indicate that OPI accurately predicts subclinical extension of NMSCs beyond visibly-involved margins in the majority of cases. Therefore, OPI holds the potential to reduce the total number of required surgical stages, possibly minimizing the unnecessary removal of normal tissue.

This paper reports on the design of a prototype in-vivo Stokes polarimetry probe for skin lesion evaluation, and preliminary results from skin phantom and clinical trials of this device. The probe releases a single millisecond-long pulse from a laser diode with either linear or circular polarization. It then captures the resulting backscattered far-field polarization speckle and calculates the Stokes parameters. This probe was designed with three novel innovations in mind. First, the Stokes vector is captured quickly, using low-cost components without the use of moving parts. Second, a compact collimated laser diode was used as the light source. Third, the device and detector geometry were designed to produce and capture a uniform speckle field. In the first clinical trial of this device, measurements were taken from a variety of skin lesions, both cancerous and benign. The Stokes vector was measured and used to calculate the degree of polarization (DOP), the azimuth angle, and the ellipticity angle of the polarization ellipse for two input light polarizations. Among other findings, the DOP for circular polarized input light was consistently lower than the DOP for linear polarized input light. These findings indicate the potential for a fast and low-cost in-vivo skin cancer screening tool, and encourages the continuing development of this probe’s techniques.

As one of the most fundamental features of light, polarization can be used to develop imaging techniques which can provide insight into the optical and structural properties of tissues. Especially, the Mueller matrix polarimetry is suitable to detect the changes in collagen and elastic fibres, which are the main compositions of skin tissue. Here we demonstrate a novel quantitative, non-contact and in situ technique to monitor the microstructural variations of skin tissue during ultraviolet radiation (UVR) induced photoaging based on Mueller matrix polarimetry. Specifically, we measure the twodimensional (2D) backscattering Mueller matrices of nude mouse skin samples, then calculate and analyze the Mueller matrix derived parameters during the skin photoaging and self-repairing processes. To induce three-day skin photoaging, the back skin of each mouse is irradiated with UVR (0.05J/cm²) for five minutes per day. After UVR, the microstructures of the nude mouse skin are damaged. During the process of UV damage, we measure the backscattering Mueller matrices of the mouse skin samples and examine the relationship between the Mueller matrix parameters and the microstructural variations of skin tissue quantitatively. The comparisons between the UVR damaged groups with and without sunscreens show that the Mueller matrix derived parameters are potential indicators for fibrous microstructure variation in skin tissue. The pathological examinations and Monte Carlo simulations confirm the relationship between the values of Mueller matrix parameters and the changes of fibrous structures. Combined with smart phones or wearable devices, this technique may have a good application prospect in the fields of cosmetics and dermatological health.

We report a low-cost optical method with high sensitivity for the quantitative assessment of the gloss of human skin in the low gloss regime relevant for physiological skin gloss conditions. Using Monte Carlo simulations, experiments on gloss calibration standards and in-vivo skin gloss experiments using an optical prototype, we demonstrate the improved sensitivity of the proposed method in the low gloss regime compared to professional industrial and skin gloss measurement devices.

Photodynamic therapy (PDT) has shown superiorities of noninvasiveness and high-efficiency in the treatment of early-stage skin cancer. Rapid and accurate determination of spatially distributed photon fluence in turbid tissue is essential for the dosimetry evaluation of PDT. It is generally known that photon fluence can be accurately obtained by Monte Carlo (MC) methods, while too much time would be consumed especially for complex light source mode or online real-time dosimetry evaluation of PDT. In this work, a method to rapidly calculate spatially distributed photon fluence in turbid medium is proposed implementing a classical perturbation and iteration theory on mesh Monte Carlo (MMC). In the proposed method, photon fluence can be obtained by superposing a perturbed and iterative solution caused by the defects in turbid medium to an unperturbed solution for the background medium and therefore repetitive MMC simulations can be avoided. To validate the method, a non-melanoma skin cancer model is carried out. The simulation results show the solution of photon fluence can be obtained quickly and correctly by perturbation algorithm.

OCT is a non-invasive imaging technique that can be applied to diagnose various skin disease. Since its introduction in 1997, dermatology has used OCT technology to obtain high quality images of human skin.

Recently, in order to accurately diagnose skin diseases, it is essential to develop OCT equipment that can obtain high quality images. Therefore, we developed the system that can obtain a high quality image by using a 1300 nm light source with a wide bandwidth and deep penetration depth, high-resolution image, and a camera capable of high sensitivity and high speed processing.

We introduce the performance of the developed system and the clinical application data.

The lymphatic system plays an important role in inflammation and cancer such as melanoma. Due to the limitations of current developed imaging techniques, visualization of lymphatic vessels within the tissue in vivo has been challenging. Optical imaging of lymphatic vessel is gaining increased interests because it does not involve any radiation and can achieve very high resolution. Here, we developed a multi-contrast, label-free optical coherence tomography (OCT) imaging technology with an axial resolution of ~ 5 μm and lateral resolution of ~ 7 μm, which is capable of providing microstructural information and microcirculatory system including blood and lymphatic vessels simultaneously. Using this technique, we observed the melanoma mice in vivo. Mice were treated topically on the ear with (Z)-4- Hydroxytamoxifen(4-OHT) to elicit BRAF^V600E and to silence Pten expression. Also, to observing the structural information, angiogenesis and lymphangiogenesis in the ear of the induced melanoma mouse can be done. The advantage of using OCT over other imaging modalities is its ability to assess label-free blood flow along with lymphatic vessels simultaneously for imaging the microcirculatory system within tissue beds without any exogenous agents. Because the metastasis of melanoma is highly related to the lymphatic vessels, our findings can be a powerful tool to help the diagnosis of the metastasis melanoma. In the future, this may become a helpful tool for better understanding pathologic mechanisms and treatment technique development in some diseases.

In this study, we assess the applicability of optical coherence tomography (OCT) for non-invasive imaging of skin morphology for the assessment of efficacy of cosmetic skin wrinkle-reduction products in humans. Evaluation of skin care products for reduction of facial wrinkles is largely limited to photographic (non-quantitative) comparison of skin surface texture before and after either single or prolonged application of skin care product. OCT could be a technique for monitoring changes in cross-sectional skin morphology. An optical attenuation coefficient analysis is also carried out to quantitatively study the changes in different layers of the skin.

Delay and sum (DAS) is the most common beamforming algorithm in linear-array photoacoustic imaging (PAI) as a result of its simple implementation. However, it leads to a low resolution and high sidelobes. Delay multiply and sum (DMAS) was used to address the incapabilities of DAS, providing a higher image quality. However, the resolution improvement is not well enough compared to eigenspace-based minimum variance (EIBMV). In this paper, the EIBMV beamformer has been combined with DMAS algebra, called EIBMV-DMAS, using the expansion of DMAS algorithm. The proposed method is used as the reconstruction algorithm in linear-array PAI. EIBMV-DMAS is experimentally evaluated where the quantitative and qualitative results show that it outperforms DAS, DMAS and EIBMV. The proposed method degrades the sidelobes for about 365 %, 221 % and 40 %, compared to DAS, DMAS and EIBMV, respectively. Moreover, EIBMV-DMAS improves the SNR about 158 %, 63 % and 20 %, respectively.