Feature characterization of scarring and non‐scarring types of alopecia by multiphoton microscopy

Abstract

OBJECTIVES: Non-invasive visualization of hair follicles is important for proper diagnosis and management of alopecia; however histological assessment remains the gold standard. Laser imaging technologies have made possible noninvasive in vivo evaluation of skin and hair follicle. The aim of this study was to evaluate the ability of multiphoton microscopy (MPM) to non-invasively identify morphological features that can distinguish scarring from non-scarring alopecia. METHODS: MPM images were obtained from areas on the scalp affected by alopecia. Investigators blinded to the diagnosis analyzed hair follicle and shaft sizes. Patients were recruited and imaged at the UC Irvine Health Medical Center and the University of California, Irvine Beckman Laser Institute. Patients with androgenetic alopecia (AGA) and alopecia areata (AA), and scarring alopecia, in particular frontal fibrosing alopecia (FFA) were recruited and imaged from July 2016 – July 2017. RESULTS: We imaged 5 normal scalp subjects and 12 patients affected by non-scarring (7 subjects) and scarring (5 subjects) alopecia. In normal and non-scarring alopecia patients, MPM identified presence of sebaceous glands associated with hair follicles. MPM images of scarring alopecia were characterized by the presence of inflammatory cells surrounding hair follicles. Measurements of hair follicle diameter sizes were found to be significantly smaller in scarring alopecia patients compared to normal (p<0.001) and compared to non-scarring alopecia patients (p=0.046); non-scarring hair follicles were also significantly smaller than normal hair follicles (p=0.043). CONCLUSIONS: This study shows that MPM imaging can non-invasively identify morphological features that distinguish scarring from non-scarring alopecia. Further studies are needed to validate this technique and evaluate its potential to be used as an aid for guiding treatment.

In vivo multiphoton imaging for non‐invasive time course assessment of retinoids effects on human skin

“…Epidermis and superficial dermis can be characterized with sub-micrometer resolution up to ~160-200 µm depth, by taking advantage of intrinsic multiphoton signals: second-harmonic generation (SHG) created by fibrillar collagens and two-photon excited fluorescence (2PEF) emitted by keratin, nicotinamide adenine dinucleotide, flavin adenine dinucleotide, melanin, or elastin. 3 The advent of medically approved multiphoton microscopes 4 enabled a broad range of clinical applications spanning from the characterization of human skin pigmentation, 3,5,6 age-related, or photoaging changes, [7][8][9][10][11][12] dermatological disorders and melanoma [13][14][15][16][17][18][19][20][21] up to the assessment of penetration and effects of pharmaceutical/ cosmetic products on human skin. 3,12,[22][23][24][25][26][27][28] Multiphoton images of in vivo human skin contain a lot of valuable information that can be extracted using appropriate image processing tools.…”

FLAME: Macroscopic imaging with microscopic resolution. Optical biopsy of human skin

“…Penetration depth can be optimized by using a longer excitation wavelength [32][33][34] , by compensating for dispersion to maintain the laser pulse duration within the tissue 35 or by adaptive optical correction of aberrations to recover diffraction-limited performance at depth in tissue 36 . Despite this limitation, the current penetration depth of 150-200 μm is sufficient to capture early signs of malignancy in skin that occur at the DEJ 5,7,8 , to detect the presence of dermal melanocytes 7 and to identify existing or prior inflammatory response in the papillary dermis 9,10 .…”

“…These fluorophores may provide additional contrast based on two-photon fluorescence lifetime detection 3,4 . In the past decade, the MPM technology has been evaluated as a clinical imaging tool in applications related to diagnosis of skin cancer [5][6][7][8] , pigmentary skin disorders 9 and alopecia 10 , characterization and understanding of skin pigment biology 11 and keratinocytes metabolism 12 or monitoring the effects of cosmetic treatments 13 . While these studies demonstrate the unique clinical potential of this technology, its routine implementation into clinical practice is hindered by several technological barriers.…”

Assessing the severity of psoriasis through multivariate analysis of optical images from non-lesional skin

“…For full details of the imaging system please refer to (Weinigel et al) 14 . MPTflex is a CE marked class 1 M /IIa medical product that has been used in numerous clinical studies in Europe and the U.S. 9,[27][28][29] .…”