Changing paradigms in dermatology: new ways to examine the skin using noninvasive imaging methods

Methods for skin image analysis and their applications in dermatology and cosmetic research: a comprehensive review

INTRODUCTION

In recent years, several non-invasive imaging methods have been introduced to facilitate studies in dermatology and cosmetic research, almost completely replacing invasive methods such as biopsy. Imaging devices have proven to be useful tools in skin analysis and therapy monitoring. This review aimed to investigate the most recent studies in cosmetic dermatology the imaging technology and methods that are being used to assess skin characteristics and summarize its fundamentals, possible applications, advantages, and limitations, and to give a future perspective to the clinical trials.

EVIDENCE ACQUISITION

For that, a literature review was carried out in the main scientific database platforms and the studies associating skin image analysis with dermatology and cosmetic research were selected and discussed.

EVIDENCE SYNTHESIS

It was possible to infer that skin image analyses are not only practical and effective, but have also become increasingly essential for the skin sciences. The in vivo and real-time image analyses allow a more complete evaluation and the follow-up of the same region for different periods. It was also possible to observe that macroscopic, microscopic, and mesoscopic imaging methods are complementary, allowing different approaches in the same study.

CONCLUSIONS

These technologies are expected to evolve more and more quickly in the near future.

Potential use of OCT-based microangiography in clinical dermatology

BACKGROUND

Optical coherence tomography (OCT) is a revolutionary imaging technique used commonly in ophthalmology, and on the way to become clinically viable alternative in dermatology due to its capability of acquiring histopathology level details of in vivo tissue, non-invasively. In this study, we demonstrate the capabilities of OCT-based microangiography in detecting high resolution, three-dimensional structural, and microvascular features of in vivo human skin with various conditions.

METHODS

A swept-source OCT system that operates on a central wavelength of 1310 nm with an A-line rate of 100 kHz is used in this study. We apply optical microangiography (OMAG) technique to visualize the structural and microvascular changes in tissue.

RESULTS

OMAG images provide detailed visualization of functional microvasculature of healthy human skin from cheek and forehead areas, abnormal skin conditions from face, chest and belly. Moreover, OMAG is capable of monitoring the progress of wound healing on human skin from arm, delivering unprecedented detail of microstructural and microvascular information during longitudinal wound healing process.

CONCLUSION

The presented results promise the clinical use of OCT angiography, aiming to treat prevalent cutaneous diseases, by detecting blood perfusion, and structural changes within human skin, in vivo.

Confocal laser scanning microscopy in vivo for diagnosing melanocytic skin neoplasms

The authors discuss the use of confocal laser scanning microscopy in vivo (CLSM) for diagnosing melanocytic skin neoplasms and its value for early diagnostics of melanoma. CLSM is an innovation noninvasive visual examination method for real-time multiple and painless examinations of the patient’s skin without injuring the skin integument. The method ensures early diagnostics of skin melanomas with high sensitivity and specificity, which makes it possible to use CLSM for screening melanocytic skin neoplasms for the sake of the early onset of treatment to save patient life and health.

Up-to-date non-invasive visualization technologies in dermatology

The authors present a review of up-to-date non-invasive visualization methods used in diagnostics of diseases of skin and its appendages. They describe physical principles forming the basis for non-invasive visualization methods such as dermatoscopy, confocal laser scanning microscopy, optical video monitoring, optical topometry, optical coherent tomography, ultrasound scanning, 3D-modeling. They also describe the potential of practical application of these diagnostics methods at the current stage of their development. The authors have demonstrated that it is possible to reduce the clinicians need in biopsy diagnostics due to the high information value of non-invasive visual diagnostics methods.

Comparative analysis of two methods for wound bed area measurement

Wound bed area measurements are considered to be an essential part of the wound assessment process. Wound care professionals should be aware of the reliability and validity of the techniques they use. The purpose of this study was to assess whether wound care professionals are able to make as accurate and reproducible a measurement of the wound bed area using two methods for area measurement. Five wound care professionals independently assessed 2285 digital wound images for the wound bed area. Each image was measured in random order, three times, and in four angles by providing the rotated versions of each image (0°, 90°, 180° and 270°). Two techniques were compared: free hand drawing and closed polygon (CP) graph algorithm. Comparison of the two techniques showed differences that are, in our opinion, not acceptable in clinical practice when these techniques are used interchangeably and/or the measurements are carried out by different observers. Variations observed between wounds and observers seem related to the difference in perception of the wound bed margin. Our results indicate that repetition of CP graph area measurement results in the lowest difference in repetitive measurements. Study limitations are related to an incomplete consensus on definitions of wound, wound bed, wound edge and wound border. The development of an ontology related to wound images could aid to reduce these ambiguities.

Objective and quantitative evaluation of scar color using the L*a*b* color coordinates

Scar color evaluation by clinical physicians has been based on subjective judgments. The purpose of this study was to investigate the application of a novel photographic analysis to produce an objective and quantitative measurement of scar color using the L*a*b* color coordinates. Three plastic surgeons evaluated photos of 207 scars using the clinical scar assessment scale developed by Beausang et al. Scar color was subjectively classified as group 1 (perfect match), 2 (slight mismatch), 3 (obvious mismatch), or 4 (gross mismatch). Three general physicians quantified color differences between the scar and the surrounding normal skin using the L*a*b* color coordinates. The total color difference (DeltaT*) and the color differences for each coordinate (DeltaL*, Deltaa*, and Deltab*) were calculated. The measurement was performed 3 times with a 4-week interval. Group 1 contained 51 scars, group 2 had 68, group 3 had 46, and group 4 had 42. The mean (SD) total color difference values (DeltaT*) for each group were 4.4 (1.83), 9.55 (2.18), 17.76 (2.96), and 29.06 (9.45), respectively (P < 0.001). The mean of each color coordinate (DeltaL* = light to dark, and Deltaa* = green to red) also differed between the groups, except in groups 1 and 2. The mean Deltab* (blue to yellow) did not differ between the groups. The correlation coefficients for interrater reliability and test-retest consistency were satisfactory. Objective scar evaluation using the L*a*b* color coordinates is found to be a reliable method to quantify scar color. With further study, this method could be simple and effective to assess the effects of scar management.

DermLite II: an innovative portable instrument for dermoscopy without the need of immersion fluids

The DermLite II is an improvement on a previous instrument allowing for dermoscopy to be carried out without the need of immersion oil. It consists of a magnifying lens encircled by light-emitting diodes that can be adjusted for polarization or can be customized by the manufacturer to produce colors of specific wavelengths for visualizing pigmentation and structures of various dermal depths. This new version of the DermLite makes it very convenient for the evaluation of not just pigmented lesions, but nonpigmented skin cancers, scalp disease, and vascular patterns. It can be attached to a camera to record images and has a retractable faceplate for use with immersion oil.