Nail thickness measurements using optical coherence tomography and 20-MHz ultrasonography

New Formulation-Microporation Combination Approaches to Delivering Ciclopirox across Human Nails

Topical treatments for onychomycosis are of interest to those seeking to avoid systemic drug interactions and to improve systemic safety. This work aimed to develop aqueous-based, simple, and cost-effective vehicles that provide high solubility for ciclopirox and enable the delivery of an active through channels created by nail microporation. Following solubility tests, aqueous gels and thermogels based on hydroxypropylmethylcellulose and poloxamer 407, respectively, were loaded with 8% and 16% ciclopirox. Their performance was then compared to the marketed lacquer Micolamina® in in vitro release tests with artificial membranes and in in vitro permeation tests with human nail clippings with and without poration. Finally, a microbiological assay compared the best gel formulations and the reference product. Little correlation was observed between the in vitro release and the permeation data, and the drug release was highly membrane-dependent. Ciclopirox nail retention in single-dose, porated nails tests was larger than in daily-dosing, non-porated nail conditions. The series of new gel and thermogel vehicles delivered ciclopirox more effectively than Micolamina® in single-dose, porated nail experiments. The inhibition of Trichophyton rubrum activity was significantly increased with microporated nails when the gel formulations were applied but not with Micolamina®. Overall, the results suggest that the new vehicles could be successfully combined with nail microporation to improve the drug delivery and efficacy of topical antifungal medication while reducing the dosing frequency, facilitating patients' adherence.

Self-induced nail disorders (SINDs): What do we know so far?

Self-induced nail disorders are a broad group of different clinical manifestations that share the common trait of being caused more or less voluntarily by the patient. These are distinct conditions within the clinical spectrum of onychotillomania. Most patients diagnosed with these disorders have psychiatric co-morbidities, and a multidisciplinary approach is thus highly recommended. The purpose of this review is to describe the most common clinical features encountered during daily nail consultations and to provide useful diagnostic tools and therapeutic tips for the best approach to these conditions.

Examination of Subungual Hematomas and Subungual Melanocytic Lesions by Using Optical Coherence Tomography and Dermoscopy

INTRODUCTION

Examination of subungual pigmented lesions is sometimes a diagnostic challenge for clinicians.

OBJECTIVES

The study was aimed to investigate characteristic patterns in optical coherence tomography (OCT) of subungual hematomas and determine distinctive features that can differentiate them from subungual melanocytic lesions.

METHODS

VivoSight® (Michelson Diagnostics, Maidstone, UK) was used to examine 71 subungual hematomas and 11 subungual melanocytic lesions in 69 patients (18 female and 51 male patients).

RESULTS

On OCT, bleeding was related to sharply defined black sickle-shaped (p < 0.001) or globular regions (not significant [ns]) with a hyperreflective margin (0.002), a grey center (0.013), hyperreflective lines in the area (ns) or periphery (p = 0.031), peripheral fading (p = 0.029), and red dots in the area (p = 0.001). In the 1 case of melanoma in situ examined, we found curved vessels with irregular sizes and distribution on the dermis of the nailbed, while subungual hematomas and subungual benign nevi presented as clustered red dots and/or regularly distributed curved vessels.

CONCLUSION

Our findings indicate that the use of OCT in addition to dermoscopy provides high-resolution optical imaging information for the diagnosis of subungual hematoma and facilitates the differential diagnosis of subungual hematomas and subungual melanocytic lesions.

[Optical coherence tomography for the differential diagnosis of unclear nail pigmentation]

In daily practice, nail pigmentation can be a diagnostic challenge, especially if the dermoscopic findings are nonspecific. We present examples of cases, in which optical coherence tomography-a rapid, noninvasive imaging method-showed typical changes that were indicative for the diagnosis.

Three-Dimensional Structure Analysis of Mouse Nails using Synchrotron Radiation

Until now, studies on nail disease have been performed through microscopic diagnosis and microscopic computed tomography (micro-CT). However, these kinds of conventional methods have some limitations. Firstly, the microscopic method is considered the gold standard for medical diagnosis. However, due to the use of fluorescent materials, the sample is damaged and it takes a long time to get results. Secondly, while micro-CT is a non-invasive method to get inner structure images of the sample with high resolution, the penetration and spatial resolution are insufficient for studying the microstructures of the sample, such as the sponge bone and the muscle fibers. In contrast, synchrotron radiation (SR) X-ray imaging technology has the advantage of very vividly demonstrating the anatomic structure of the sample with high penetration, sensitivity, and resolution. In this study, we compared the optical microscopic method using hematoxylin and eosin (H&E) staining and SR imaging to analyze the nail tissue in a mouse model. The results showed that SR could depict the inner structures of a mouse nail without physical damage. Additionally, we could divide the important anatomical structures nail unit into three parts with three-dimensional images: the nail bed, nail matrix, and hyponychium. The images showed that SR could be used for analyzing nails by visualizing the relatively clear and medically semantic structures in a three-dimensional section. We expect that the results of this study will be applied to study nail diseases and pharmaceutical research on their treatment.

A preliminary study of post-progressive nail-art effects on in vivo nail plate using optical coherence tomography-based intensity profiling assessment

Nail beautification is a widely applied gender independent practice. Excessive nail beautifications and nail-arts have a direct impact on the nail structure and can cause nail disorders. Therefore, the assessment of post-progressive nail-art effects on the nail is essential to maintain optimal nail health and to avoid any undesirable disorders. In this study, in vivo nails were examined in control stage, with a nail-art stage, and after removing the nail-art stage using a 1310 nm spectral-domain optical coherence tomography (SD-OCT) system. The acquired cross-sectional OCT images were analyzed by a laboratory customized signal processing algorithm to obtain scattered intensity profiling assessments that could reveal the effects of nail beautification on the nail plate. The formation and progression of cracks on the nail plate surface were detected as an effect of nail beautification after 72 h of nail-art removal. Changes in backscattered light intensity and nail plate thickness of control and art-removed nails were quantitatively compared. The results revealed the potential feasibility of the developed OCT-based inspection procedure to diagnose post-progressive nail-art effects on in vivo nail plate, which can be helpful to prevent nail plate damages during art removal through real-time monitoring of the boundary between the nail plate and nail-art. Besides nail-art effects, the developed method can also be used for the investigation of nail plate abnormalities by examining the inconsistency of internal and external nail plate structure, which can be diagnosed with both qualitative and quantitative assessments from a clinical perspective.

Applications and future directions for optical coherence tomography in dermatology

Optical coherence tomography (OCT) is a noninvasive optical imaging method that can generate high-resolution en face and cross-sectional images of the skin in vivo to a maximum depth of 2 mm. While OCT holds considerable potential for noninvasive diagnosis and disease monitoring, it is poorly understood by many dermatologists. Here we aim to equip the practising dermatologist with an understanding of the principles of skin OCT and the potential clinical indications. We begin with an introduction to the technology and discuss the different modalities of OCT including angiographic (dynamic) OCT, which can image cutaneous blood vessels at high resolution. Next we review clinical applications. OCT has been most extensively investigated in the diagnosis of keratinocyte carcinomas, particularly basal cell carcinoma. To date, OCT has not proven sufficiently accurate for the robust diagnosis of malignant melanoma; however, the evaluation of abnormal vasculature with angiographic OCT is an area of active investigation. OCT, and in particular angiographic OCT, also shows promise in monitoring the response to therapy of inflammatory dermatoses, such as psoriasis and connective tissues disease. We additionally discuss a potential role for artificial intelligence in improving the accuracy of interpretation of OCT imaging data.

Morphometric Optical Imaging of Microporated Nail Tissue: An Investigation of Intermethod Agreement, Reliability, and Technical Limitations

BACKGROUND AND OBJECTIVES

While optical imaging is a useful technique to quantitate morphological differences and treatment effects, comparative investigations of the various techniques are lacking. This study aimed at evaluating intermethod agreement, reliability, and technical limitations of wide-field microscopy (WFM), reflectance confocal microscopy (RCM), and optical coherence tomography (OCT) for morphometry by assessing fractionally ablated nail tissue.

STUDY DESIGN/MATERIALS AND METHODS

Fifty healthy nail clippings were processed with a fractionated CO₂ -laser (20 mJ/microbeam, density 15%), measured with calipers, and imaged using WFM, OCT, and RCM. Images were assessed for nail plate thickness, micropore dimensions, degree of poration, and artifacts. Repeated measurements (2-5) were taken to evaluate method repeatability using Cronbach's α and coefficients of variation (CoV), and estimate the intermethod correlation through linear correlation assessment (Pearson correlation coefficient [PCC]), ranked correlation (Kendall's tau; tau-c), and intraclass correlation (Shrout-Fleiss reliability coefficient; ICC).

RESULTS

The repeatability varied substantially between methods and target measurements. The level of intermethod agreement for thickness measurements performed with calipers, WFM, and OCT was high (tau-c ≥ 0.7; ICC ≥ 0.8; PCC ≥ 0.9). RCM could only image 28 out of 50 samples due to its limited penetration depth. OCT demonstrated the highest repeatability of all imaging techniques (CoV 4-7%) and nail thickness showed the highest measurement reliability (α = 0.92). Micropore dimensions correlated strongest between OCT and RCM (tau-c/ICC/PCC ≥ 0.5). All modalities were prone to artifacts, which may have adversely affected measurement variation and intermethod agreement.

CONCLUSION

Intermethod agreement and reliability appear to be highly dependent on the specific modality and target measurement. To reap the benefits of each technique while mitigating their limitations, an integrated approach to optical imaging is recommended. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Impregnation of healthy nail tissue with optical clearing agents for improved optical coherence tomography imaging

OBJECTIVES

The impact of optical tissue clearing on optical coherence tomography (OCT) for nail tissue imaging has not been investigated. This study seeks to compare the effects of an emollient and water on visualization of micromorphology and morphometric outcomes.

MATERIALS AND METHODS

Thirty-six healthy nail plates were processed with a fractional CO₂ laser, imaged with OCT, and measured with calipers in duplicates. All samples were reassessed after 12-hour long sequential immersion in water and an emollient (Crodamol™ STS). OCT images were evaluated for thickness and scattering signal of the nail.

RESULTS

Emollient-impregnation caused stronger scatter responses (P < .0001) and decreased nail thickness (MD 45 μm, P < .0001) measured on OCT. Caliper-derived measurements were not affected by Crodamol™ (MD 11 μm, P = .5538). Hydration increased nail thickness on OCT (MD 49 μm, P < .0001) but reduced thickness measurements taken with calipers (MD 41 μm, P < .0001). Emollient-impregnation improved visualization of onychocytes compared with dry (P = .0209) and hydrated samples (P < .0001), and reduced occurrence of refractive artifacts (P < .0001).

CONCLUSION

The use of an emollient for OCT imaging can enhance nail tissue visualization without significant effects on caliper measurements. Hydration of nails, in contrast with emollient-impregnation, may lead to disagreement between caliper- and OCT-measured nail thickness and should be practiced cautiously.

Emerging Optical Techniques for the Diagnosis of Onychomycosis

Onychomycosis is the most prevalent nail infection. Although it is not a life-threatening condition, it impacts the quality of life for many patients and often imposes a challenging diagnostic problem. The causative agents are dermatophytes, yeasts and non-dermatophytic moulds. Accurate and early diagnosis, including the identification of the causative species, is the key factor for rational therapy. Still, early diagnosis is not optimal as the current gold standard for the differentiation of the infectious agents is culture-based approaches. On the other hand, noninvasive optical technologies may enable differential diagnosis of nail pathologies including onychomycosis. When light penetrates and propagates along the nail tissue, it interacts in different ways with the components of either infected or healthy nail segments, providing a wealth of diagnostic information upon escaping the tissue. This review aims to assess alternative optical techniques for the rapid diagnosis of onychomycosis with a potential to monitor therapeutic response or even identify the fungal agent non-invasively and in real time in a clinical setting.

Optical coherence tomography of onychomycosis: proposed terminology and a suggestion of practical usage

Onychomycosis is the most common cause of nail changes accounting for about half of all nail diseases. It is important to diagnose the fungal pathogen to prescribe adequate treatment, but as genus- and species-specific diagnostic tests can be time consuming and expensive, it is crucial to obtain representative tissue during nail scrapings. Optical coherence tomography (OCT) is a non-invasive imaging tool enabling real-time imaging of skin and tissue. Pilot studies using OCT have described morphological characteristics of onychomycosis, though diagnostic criteria of onychomycosis and other nail diseases are lacking. The aim of this study is to investigate the applicability of OCT to detect and localize fungal elements in nails with clinical signs of onychomycosis. OCT scans and nail scrapings were performed on all participants and only confirmed cases of onychomycosis were included in the data analysis. All scans were analyzed, and a set of morphological criteria based on known literature and deviations from healthy nail morphology were suggested. The suggested morphological features were: hyperreflective lines divided into sharply and diffusely demarcated; hyperreflective dots divided into singular and clustered patterns; irregular surface, divided into mild, moderate and severe degree; dark bands and disturbed architecture. The suggested OCT morphology is a refinement of previous studies, and though OCT cannot replace genus- or species-specific identification, it could be a useful assistance tool to increase diagnostic sensitivity of nail scrapings and laboratory tests as well as for monitoring treatment response.

Two optical coherence tomography systems detect topical gold nanoshells in hair follicles, sweat ducts and measure epidermis

Optical coherence tomography (OCT) is an established imaging technology for in vivo skin investigation. Topical application of gold nanoshells (GNS) provides contrast enhancement in OCT by generating a strong hyperreflective signal from hair follicles and sweat glands, which are the natural skin openings. This study explores the utility of 150 nm diameter GNS as contrast agent for OCT imaging. GNS was massaged into skin and examined in four skin areas of 11 healthy volunteers. A commercial OCT system and a prototype with 3 μm resolution (UHR-OCT) were employed to detect potential benefits of increased resolution and variability in intensity generated by the GNS. In both OCT-systems GNS enhanced contrast from hair follicles and sweat ducts. Highest average penetration depth of GNS was in armpit 0.64 mm ± SD 0.17, maximum penetration depth was 1.20 mm in hair follicles and 15 to 40 μm in sweat ducts. Pixel intensity generated from GNS in hair follicles was significantly higher in UHR-OCT images (P = .002) and epidermal thickness significantly lower 0.14 vs 0.16 mm (P = .027). This study suggests that GNSs are interesting candidates for increasing sensitivity in OCT diagnosis of hair and sweat gland disorders and demonstrates that choice of OCT systems influences results.

Structural and component mining of nails using bioengineering techniques

The human nail is one of the challenging membranes for the scientists to target and to improve the clinical efficacy of ungual formulations. The understanding of nail physiology, impact of hydration on its properties and presence of trace elements in nails as biomarkers has been explored by various researchers in clinical studies. Despite the importance of biophysical techniques for the assessment of structure and physiology of nail, minimum literature analyses biophysical, biochemical and bioanalytical approaches. However, nowadays scientists in bioengineering field are keen in developing non-invasive, reliable and reproducible techniques for the assessment of different anatomical and functional parameters of nails for testing of ungual products.

Speckled variance optical coherence tomography for the assessment of nail involvement in acrodermatitis continua of Hallopeau: A case study

Noninvasive techniques for nail imaging would be useful for confirming diagnosis and monitoring treatment response at the microscopic level in patients with nail psoriasis. However, the use of ultrasound and high-resolution magnetic resonance imaging in nail evaluation is limited. Optical coherence tomography (OCT) produces high-resolution images of transversal tissue sections and represents an optimal approach to the study of the nail. This study used a multibeam OCT instrument to produce speckled variance OCT (SV-OCT) blood-flow images, which were used to measure the degree of change over successive scans. Nail changes, inflammation and response to therapy were evaluated in a 75-year-old female patient with psoriasis who had severe acrodermatitis continua of Hallopeau of the hands, treated for 4 weeks with 40 mg adalimumab (administered subcutaneously every other week) and 25 mg prednisone (administered orally, daily). SV-OCT provided a detailed assessment of the nail structures in relation to inflammation of psoriatic tissues. Restoration of the normal anatomy of the nail apparatus was apparent following adalimumab treatment; SV-OCT evaluation correlated with clinical appearance. SV-OCT may have a diagnostic role and provide an objective tool to assess clinical and subclinical inflammation in nail psoriasis.

Vascular Features of Nail Psoriasis Using Dynamic Optical Coherence Tomography

BACKGROUND

Nail psoriasis is a painful and disfiguring nail disease that often leads to invasive biopsies. Dermoscopy of the hyponychium can be useful in the diagnosis showing twisted coiled vessels. Structural features of nail psoriasis have been described with optical coherence tomography (OCT).

OBJECTIVES

To investigate vascular features of nail psoriasis using dynamic OCT.

METHODS

This was an observational, prospective, controlled study in which psoriasis patients with psoriatic nail changes and healthy control patients underwent OCT imaging of the distal nail plate and proximal nail fold. Vertical and horizontal OCT images were analyzed to describe structural and vascular features and to quantify blood flow at depth.

RESULTS

Sixteen psoriatic nails and 16 control nails were included. Psoriatic nails had significantly increased blood flow in the proximal nail fold at depths of 0.72 mm (p = 0.035) and 0.76 mm (p = 0.027). Nail thickness was significantly greater in psoriatic nails compared to control nails (p = 0.0016). Compared to control nails, psoriatic nails had dilated, disorganized blood vessels superficially in the proximal nail fold.

LIMITATIONS

The main limitation of our study is the relatively small sample size.

CONCLUSIONS

OCT can identify structural and vascular features specific to nail psoriasis.

Imaging of collagen deposition disorders using optical coherence tomography

BACKGROUND

Collagen deposition disorders such as hypertrophic scars, keloids and scleroderma can be associated with significant stigma and embarrassment. These disorders often constitute considerable impairment to quality of life, with treatment posing to be a substantial challenge. Optical coherence tomography (OCT) provides a non-invasive, easily applicable bedside optical imaging method for assessment of the skin. It is hypothesized that OCT imaging may be useful in assessing fibrosis to avoid additional biopsies that could potentially worsen the scarring.

METHOD

Thirty-three patients with ordinary scars, hypertrophic scars, keloid scarring, lichen sclerosus et atrophicus and localized or systemic scleroderma were recruited for this pilot study. Affected tissue and adjacent healthy skin were scanned using OCT and digitally photographed. Density measurements were performed in ImageJ on OCT images from scleroderma patients, both systemic and morphea (10 patients), keloid patients (10 patients) and healthy skin adjacent to keloids (10 patients).

RESULTS

OCT images of scarring diseases showed varying degrees of disruption to the skin architecture. OCT characteristics were identified for each lesion type. Hypertrophic scars displayed an increased vascularity and signal-rich bands correlating to excessive collagen deposition. Keloids depicted a disarray of hyper-reflective areas primarily located in the upper dermis. Additionally, the dermis displayed a heterogeneous morphology without indications of any vascular supply or lymphatic network. In contrast to keloids, scleroderma displayed a more cohesive backscattering indicating a difference in density of collagen or other dermal structures. OCT images demonstrated no significant differences between mean density measurements in OCT images of scleroderma, keloid and healthy skin (P = 0.07).

CONCLUSION

The OCT imaging appears to identify different scarring mechanisms, and therefore be of potential use in the assessment of outcomes following non-invasive therapy of e.g. early or progressive lesions.

Nail anatomy

The nail unit comprises the nail plate, the surrounding soft tissues, and their vasculature and innervation based upon the distal phalanx. The nail plate is a laminated keratinized structure lying on the nail matrix (15-25%), the nail bed with its distal onychodermal band (75-85%), and the hyponychium at its free edge. The distal part of the matrix, the lunula characterized by its half-moon shape, can be observed in some digits. The nail plate is embedded by the proximal and lateral folds. From the proximal nail fold, the cuticle (also known as the eponychium), adheres to the superficial surface of the proximal nail plate. The nail unit possesses a complex and abundant vascular network to ensure adequate blood supply. Finally, both the periungual soft tissues and the nail folds are innervated. The shapes, structure, and inter-relationships of these tissues are factors in the way nails present with disease and how we understand and manage those diseases. In particular, an understanding of the surgical anatomy is important for those undertaking diagnostic or curative operations on the nail. With this knowledge, the most appropriate surgery can be planned and the patient can be provided with accurate and clear guidance to enable informed consent.

Ultrasonographic assessment of nail in psoriatic disease shows a link between onychopathy and distal interphalangeal joint extensor tendon enthesopathy

OBJECTIVE

We compared ultrasonography (US) with the modified nail psoriasis severity index (mNAPSI) to investigate the nail plate, nail matrix and adjacent tendons in subjects with psoriatic nail disease and to test the hypothesis that nail involvement was specifically linked to extensor tendon enthesopathy.

METHODS

86 psoriatic patients (169 nails) and 20 healthy controls (HC) (40 nails) were assessed with both the mNAPSI and US. The thickness of the nail plate, nail matrix region and adjacent extensor tendon were assessed and compared with physical examination findings.

RESULTS

A good agreement between clinical and sonographic nail findings was noted (kappa value = 0.52, p < 0.0001). Entheseal thickening of the extensor tendon on US was more frequent in patients with clinical nail disease compared to patients without clinical nail disease in both psoriasis and psoriatic arthritis (38 vs. 16%, p = 0.03, and 47 vs. 19%, p = 0.008, respectively). Nail thickness, nail matrix and adjacent skin thickness were higher in psoriatic patients compared to HC.

CONCLUSION

US and clinical findings show good correlation for the assessment of the nail in psoriatic disease. The demonstration of extensor tendon enthesopathy in both psoriasis and psoriatic arthritis supports the importance of enthesopathy in nail disease pathogenesis whether or not clinical arthritis is present.

High-resolution ultrasonography in assessment of nail-related disorders

OBJECTIVE

Disorders of the nail can pose a diagnostic challenge, and non-invasive imaging is frequently required to clarify diagnosis and delineate anatomy pre-operatively. We explored the use of high-resolution ultrasonography in the assessment of patients with nail disorders attending orthopaedic hand clinics.

METHODS

A search of a university teaching hospital musculoskeletal radiology database identified 36 patients (mean age 54.2 years) where ultrasonography was used to assess nail-related disorders between April 2003 and January 2007. Clinical, surgical and histological findings were correlated in these cases with ultrasound reports.

RESULTS

Ultrasound findings correlated with the provisional diagnosis in 20 (61%) of 33 patients and provided a diagnosis in 3 patients where a provisional diagnosis was unavailable. In 7 of the 13 cases where the clinical diagnosis differed from ultrasound findings, a lump originally diagnosed as cystic in origin was shown to be solid on ultrasound. Different nail pathologies showed different characteristics on ultrasonography, including differences in vascularity, echogenicity, changes in nail structure/shape and extension into the nail bed, matrix, fold or evidence of bony erosion. The ultrasound findings correlated with histological analysis and intra-operative assessment in 10 of 15 patients who underwent operative treatment.

CONCLUSION

Ultrasound provides important information on the anatomy of the nail apparatus and can differentiate solid and cystic lesions. It can be used as a diagnostic tool and can therefore help in pre-operative planning of nail-related disorders. In our series ultrasound supported or improved upon the clinical diagnosis in 31 (86%) out of the 36 patients presenting with nail-related disorders.

Confocal laser scanning microscopy as a new valuable tool in the diagnosis of onychomycosis - comparison of six diagnostic methods

Onychomycosis is common and can mimic several different nail disorders. Accurate diagnosis is essential to choose the optimum antifungal therapy. The aim of this study was to evaluate the use of confocal laser scanning microscopy (CLSM) and optical coherence tomography (OCT) as new non-invasive diagnostic tools in onychomycosis and to compare them with the established techniques. In a prospective trial, 50 patients with suspected onychomycosis and 10 controls were examined by CLSM and OCT. Parallel KOH preparation, culture, PAS-staining and PCR were performed. PCR showed the highest sensitivity, followed by CLSM, PAS and KOH preparation. OCT offered the second best sensitivity but displayed the lowest specificity. CLSM and KOH preparation showed a high specificity and CLSM offered the best positive predictive value, similar to KOH preparation and OCT. Fungal culture showed the lowest sensitivity and the worst negative predictive value, yet culture and PCR are the only techniques able to identify genus and species. In summary, CLSM was comparable to PAS staining and superior to KOH preparation. Due to the low specificity we assess OCT not as appropriate. In the differentiation of species PCR outplays the fungal culture in terms of time and sensitivity.

The human nail--barrier characterisation and permeation enhancement

The human nail remains one of the most challenging membranes for formulation scientists to target and for clinicians to heal. Its formidable barrier properties are the primary reason that oral therapy remains the primary approach to manage ungual infections. This article considers the major structural properties underlying the excellent barrier function of the nail, with particular emphasis on the role of biophysical methods in advancing our knowledge of this appendage. Formulations currently available for management of ungual disease are discussed and their therapeutic efficacy is assessed. Finally, experimental strategies to enhance ungual permeation are reviewed and prospects for future developments in the field are considered.

The evaluation of nail heath conditions with skin ultrasound

BACKGROUND/PURPOSE

Skin ultrasound is a non-invasive technique widely used in the dermatological fields. Previous studies have indicated that ultrasound was able to measure nails depth. The use of ultrasound is particularly appropriate for the study of nail morphology because of the differences in tissue density. The objective of this present study was to understand the characteristics and changes of adult nail texture associated with mild irritation.

METHODS

The skin ultrasound measurement and clinical grading scales were used to evaluate nail texture and other important objective parameters relating to nail health in subjects with and without mild irritant hand eczema (IHE).

RESULTS

There was no difference in the objective parameters between the left and right hands of subjects within each group (P > 0.05). There were significant differences between the groups for the objective parameters (P < 0.05), and the left hand was more obviously damaged than the right one.

CONCLUSIONS

The surface texture of nails with IHE was different from the normal group. The nails of the IHE group were much more uneven and thicker, although there was no noticeable change in density.

Optical coherence tomography: a new tool to assess nail disease in psoriasis?

BACKGROUND

Nail disease is a characteristic manifestation of the psoriatic disease spectrum but is poorly understood.

OBJECTIVE

Given the intrinsically high spatial resolution imaging capabilities of optical coherence tomography (OCT), we assessed its value in psoriatic nail disease compared to high-resolution ultrasonography (US).

METHODS

All fingernails in a psoriatic arthritis patient with nail changes were scanned with OCT, and findings were compared with high-resolution US.

RESULTS

US showed loss of trilaminar appearance in all nails, resulting in the nail plate being visualized as a single hyperechoic layer with inhomogeneous thickness. The OCT images showed much higher-resolution changes with prominent thickening in the ventral plate at the nail bed which was grossly inhomogeneous, 'eroded' and irregularly fused with the underlying epidermis, which correlated with the clinical observation of subungal hyperakeratosis.

CONCLUSION

OCT has considerable potential for the evaluation of psoriatic nail disease and may be superior to US.

Application of stereology to dermatological research

Stereology is a set of mathematical and statistical tools to estimate three-dimensional (3-D) characteristics of objects from regular two-dimensional (2-D) sections. In medicine and biology, it can be used to estimate features such as cell volume, cell membrane surface area, total length of blood vessels per volume tissue and total number of cells. The unbiased quantification of these 3-D features allows for a better understanding of morphology in vivo compared with 2-D methods. This review provides an introduction to the field of stereology with specific emphasis on the application of stereology to dermatological research by supplying a short insight into the theoretical basis behind the technique and presenting previous dermatological studies in which stereology was an integral part. Both the theory supporting stereology and a practical approach in a dermatological setting are reviewed with the aim to provide the reader with the capability to better assess papers employing stereological estimators and to design stereological studies independently.

Optical coherence tomography for imaging of skin and skin diseases

Optical coherence tomography (OCT) is an emerging imaging technology based on light reflection. It provides real-time images with up to 2-mm penetration into the skin and a resolution of approximately 10 microm. It is routinely used in ophthalmology. The normal skin and its appendages have been studied, as have many diseases. The method can provide accurate measures of epidermal and nail changes in normal tissue. Skin cancer and other tumors, as well as inflammatory diseases, have been studied and good agreement found between OCT images and histopathological architecture. OCT also allows noninvasive monitoring of morphologic changes in skin diseases and may have a particular role in the monitoring of medical treatment of nonmelanoma skin cancer. The technology is however still evolving and continued technological development will necessitate an ongoing evaluation of its diagnostic accuracy. Several technical solutions are being pursued to further improve the quality of the images and the data provided, and OCT is being integrated in multimodal imaging devices that would potentially be able to provide a quantum leap to the imaging of skin in vivo.

Simultaneous dual-band optical coherence tomography in the spectral domain for high resolution in vivo imaging

Optical coherence tomography (OCT) in the spectral domain is demonstrated simultaneously at two wavelength bands centered at 800 nm and 1250 nm. A novel commercial supercontinuum laser is applied as a single low coherence broadband light source. The emission spectrum of the source is shaped by optical and spatial filtering in order to achieve an adequate double peak spectrum containing the wavelength bands 700 - 900 nm and 1100 - 1400 nm for dual-band OCT imaging and thus reducing the radiation exposure of the sample. Each wavelength band is analyzed with an individual spectrometer at an A-scan rate of about 12 kHz which enables real-time imaging for the examination of moving samples. A common path optical setup optimized for both spectral regions with a separate single fiber-based scanning unit was realized which facilitates flexible handling and easy access to the measurement area. The free-space axial resolutions were measured to be less than 4.5 microm and 7 microm at 800 nm and 1250 nm, respectively. Three-dimensional imaging ten times faster than previously reported with a signal-to-noise-ratio of above 90 dB is achieved simultaneously in both wavelength bands. Spectral domain dual-band OCT combines real-time imaging with high resolution at 800 nm and enhanced penetration depth at 1250 nm and therefore provides a well suited tool for in vivo vasodynamic measurements. Further, spatially resolved spectral features of the sample are obtained by means of comparing the backscattering properties at two different wavelength bands. The ability of dual-band OCT to enhance tissue contrast and the sensitivity of this imaging modality to wavelength-dependent sample birefringence is demonstrated.

OCT imaging of skin cancer and other dermatological diseases

Optical coherence tomography (OCT) provides clinicians and researchers with micrometer-resolution, in vivo, cross-sectional images of human skin up to several millimeter depth. This review of OCT imaging applied within dermatology covers the application of OCT to normal skin, and reports on a large number of applications in the fields of non-melanoma skin cancer, malignant melanomas, psoriasis and dermatitis, infestations, bullous skin diseases, tattoos, nails, haemangiomas, and other skin diseases.

Assessment of optical coherence tomography imaging in the diagnosis of non-melanoma skin cancer and benign lesions versus normal skin: observer-blinded evaluation by dermatologists and pathologists

BACKGROUND

Optical coherence tomography (OCT) is an optical imaging technique that may be useful in diagnosis of non-melanoma skin cancer (NMSC).

OBJECTIVES

To describe OCT features in NMSC such as actinic keratosis (AK) and basal cell carcinoma (BCC) and in benign lesions and to assess the diagnostic accuracy of OCT in differentiating NMSC from benign lesions and normal skin.

METHODS AND MATERIALS

OCT and polarization-sensitive (PS) OCT from 104 patients were studied. Observer-blinded evaluation of OCT images from 64 BCCs, 1 baso-squamous carcinoma, 39 AKs, two malignant melanomas, nine benign lesions, and 105 OCT images from perilesional skin was performed; 50 OCT images of NMSC and 50 PS-OCT images of normal skin were evaluated twice.

RESULTS

Sensitivity was 79% to 94% and specificity 85% to 96% in differentiating normal skin from lesions. Important features were absence of well-defined layering in OCT and PS-OCT images and dark lobules in BCC. Discrimination of AK from BCC had an error rate of 50% to 52%.

CONCLUSION

OCT features in NMSC are identified, but AK and BCC cannot be differentiated. OCT diagnosis is less accurate than clinical diagnosis, but high accuracy in distinguishing lesions from normal skin, crucial for delineating tumor borders, was obtained.

A few aspects of transonychial water loss (TOWL): inter-individual, and intra-individual inter-finger, inter-hand and inter-day variabilities, and the influence of nail plate hydration, filing and varnish

The aim of the study was to measure transonychial water loss (TOWL) in order to identify the extent of inter-individual, intra-individual inter-finger, inter-hand, and inter-day variabilities, and the influence of nail wetting, filing and varnishing on TOWL, with a view to determine parameters for the measurement of TOWL and its possible applications. Fingernail and toenail TOWL was measured using the condenser-chamber AquaFlux (Biox) and a specially designed Nail Adaptor supplied by Biox. A wide range of TOWL values (28-75g/m(2)h for fingernails and 26-48g/m(2)h for toenails) were found, with significant inter-individual variability. Intra-individual variability was lower; however, in the same individual, inter-finger, inter-hand/foot and inter-day variabilities were found, as well as a strong correlation between nail plate thickness and TOWL. Wetting the nails, even briefly, resulted in a significant rise in TOWL, which subsequently took much longer to return to control values. Filing the nail plate surface with a pharmaceutical file caused large increases in TOWL, whose profile (with number of filing strokes) was fairly different among individuals. As expected, nail varnish application reduced TOWL; the different extent of TOWL reduction by different varnishes suggests a potential use of TOWL measurements for product comparisons.