Oral and skin imaging

Optical biopsies of different skin layers. (a) Commercial optical medical imaging systems utilized for in vivo skin imaging. (b,c) Coupling imaging head to skin. (d) Representative digital photos of (left to right) healthy skin of control subjects, lesional skin of subject diagnosed with psoriasis, pseudo-control (non-lesional) skin of subject diagnosed with psoriasis, and lesional skin of subject diagnosed with eczema. (e) 2PF/SHG and FLIM images of different skin layers, (SG – stratum granulosum, SS – stratum spinosum, SB – stratum basale, UD – upper dermis). Scale bar in (e) represents 40 μm, inset numerical values in (e) represent the depth of imaging below the skin surface. Time-lapse OCT images of skin position and structures as the skin recovers to the original state.

The dental biofilm, or dental plaque, is the thin layer of disease-causing bacteria on the teeth. If the plaque is left untreated for a long period of time, the dental biofilms harden and may develop gingivitis and periodontitis, ultimately causing tooth decay. For the effective imaging of oral tissues, we have developed an interchangeable tip to be used with our OCT imaging system. With our probe-based OCT systems, we can visualize and assess dental biofilm and gum tissues, so-called gingiva, in vivo and in real-time. Gum health is highly related to dental health as well as the general health of the body. The inflammation of the gingiva can be caused by the accumulation of dental biofilm and may lead to periodontal disease. 

The biomechanical response and viscoelastic properties of human skin provide useful information in diagnosing skin pathologies. However, the examination highly relies on visual inspection and palpation, and there is currently no standard medical device that non-invasively evaluates biomechanical properties of the skin. From in vivo skin indentation experiment, we examine the biomechanical response of human skin using an OCT system and compared it between adults and infants. The polymer indenter is placed onto the skin for 3 minutes on the forearm (adults) and thigh (infants). As soon as the indenter is removed from the skin, the OCT system is employed to observe and characterize the biomechanical response of the skin as it recovers to the original state.

The high resolution and multimodal framework make the integrated microscope uniquely suited for in vivo skin imaging in a label-free manner. These advantages allow specific biological events that occurred in the skin, such as wound healing, apoptosis, and the effect of pharmaceutical treatments to be characterized longitudinally.  A variety of skin components can be visualized with the multimodal system, including collagen structure (second harmonic generation microscopy, SHG), endogenous/labeled fluorophores (two-photon excitation fluorescence, TPF), surface structure (OCT/OCM), vasculature network (phase-variance OCT, PV-OCT), and metabolic activity (fluorescence lifetime imaging microscopy, FLIM). More recently, our lab has developed a non-invasive optical method using two-photon FLIM for automated assessment of the severity of psoriasis, a skin condition that causes skin cells build up and form bumpy red, itchy, and dry patches. 

  • Huang P-C, Pande P, Shelton RL, Joa F, Moore D, Gillman E, Kidd K, Nolan RM, Odio M, Carr A, Boppart SA. Quantitative characterization of mechanically indented in vivo human skin in adults and infants using optical coherence tomography. Journal of Biomedical Optics, 22(3):034001, 2017.
  • Zurauskas M, Barkalifa R, Alex A, Marjanovic M, Spillman DR, Mukherjee P, Neitzel CD, Lee W, Medler J, Arp Z, Cleveland M, Hood S, Boppart SA. Assessing the severity of psoriasis through multivariate analysis of optical images from non-lesional skin. Scientific Reports, 10:9154, 2020.
  • Alex A, Chaney EJ, Zurauskas M, Criley JM, Spillman DR, Hutchison PB, Li J, Marjanovic M, Frey S, Arp Z, Boppart SA. In vivo characterization of minipig skin as a model for dermatological research using multiphoton microscopy. Experimental Dermatology, 00:1-8, 2020.
  • Rico-Jimenez J, Lee JH, Alex A, Musaad S, Chaney E, Barkalifa R, Olson E, Adams D, Marjanovic M, Arp Z, Boppart SA. Non-invasive monitoring of pharmacodynamics during the skin wound healing process using multimodal optical microscopy. BMJ Open Diabetes Research & Care, 8:e000974, 2020. 
  • Li J, Wilson MN, Bower AJ, Marjanovic M, Chaney EJ, Barkalifa R, Boppart SA. Video-rate multimodal multiphoton imaging and three-dimensional characterization of cellular dynamics in wounded skin. Journal of Innovative Optical Health Sciences, 13(2):205007, 2020.

Psoriasis imaging using mutimodal nonlinear microscopy

Patients with psoriasis represent a heterogeneous population with individualized disease expression. Psoriasis can be monitored through gold standard histopathology of biopsy specimens that are painful and permanently scar. A common associated measure is the use of non-invasive assessment of the Psoriasis Area and Severity Index (PASI) or similarly derived clinical assessment based scores. However, heterogeneous manifestations of the disease lead to specific PASI scores being poorly reproducible and not easily associated with clinical severity, complicating the efforts to monitor the disease. To address this issue, we developed a methodology for non-invasive automated assessment of the severity of psoriasis using optical imaging. Our analysis shows that two-photon fluorescence lifetime imaging permits the identification of biomarkers present in both lesional and non-lesional skin that correlate with psoriasis severity. This ability to measure changes in lesional and healthy-appearing skin provides a new pathway for independent monitoring of both the localized and systemic effects of the disease. Non-invasive optical imaging was conducted on lesions and non-lesional (pseudo-control) skin of 33 subjects diagnosed with psoriasis, lesional skin of 7 subjects diagnosed with eczema, and healthy skin of 18 control subjects. Statistical feature extraction was combined with principal component analysis to analyze pairs of two-photon fluorescence lifetime images of stratum basale and stratum granulosum layers of skin. We found that psoriasis is associated with biochemical and structural changes in non-lesional skin that can be assessed using clinically available two-photon fluorescence lifetime microscopy systems.

Optical skin biopsies are quantified to reveal subtle changes induced by psoriasis. Quantified biomarkers are later used for multivariate analysis and predictive modelling.

  • Zurauskas, M., Barkalifa, R., Alex, A., Marjanovic, M., Spillman, D. R., Mukherjee, P., Neitzel, C. D., Lee, W., Medler, J., Arp, Z., Cleveland, M., Hood, S. And Boppart, S. A., “Assessing the severity of psoriasis through multivariate analysis of optical images from non-lesional skin,” Sci. Rep. 10(1), 9154 (2020). 
  • Alex, A., Chaney, E. J., Žurauskas, M., Criley, J. M., Spillman Jr, D. R., Hutchison, P. B., Li, J., Marjanovic, M., Frey, S. And Arp, Z., “In vivo characterization of minipig skin as a model for dermatological research using multiphoton microscopy,” Exp. Dermatol. (2020).