Comparative study of presurgical skin infiltration depth measurements of melanocytic lesions with OCT and high frequency ultrasound

Preoperative bimodal imaging evaluation in finding histological correlations of in situ, superficial spreading and nodular melanoma

Background

The aim of this study is to correlate the diagnostic criteria described in dermoscopy, ultrasonography (US), and histology of the most common types of cutaneous melanoma (CM).

Methods

We conducted a prospective study including 40 CM cases, which were analyzed by dermoscopy using the Delta 30 dermatoscope and Vidix 4.0 videodermoscope, by ultrasound (US) using a high-resolution 20 MHz linear probe, along with histopathological analysis.

Results

The study involved 40 patients with histopathologically confirmed CM, comprising 10 nodular melanomas (NM), 21 superficial spreading melanomas (SSM), and nine in situ melanomas (MIS). US measurements of tumor thickness exhibited strong correlations with the histopathological Breslow index (BI), particularly in the NM and SSM groups. A notable correlation was observed between the presence of ulceration in histopathology and ultrasonography. Dermoscopic analysis revealed significant associations between specific features and CM types. For instance, the presence of an atypical network, irregular globules, irregular dots, prominent skin margins, angulated lines/polygons, dotted and short linear vessels, and negative network correlated with a median BI ≤ 0.5 mm. Conversely, the presence of blue-white veil, atypical vessels, blue-black color, and milky red color were associated with a median BI ≥ 2.3 mm. Furthermore, regression observed in histopathology correlated with regression identified in dermoscopy, we also found statistical correlations between the presence of vascularization at US with the high Clark level, and the presence of prominent skin markings at dermoscopy. The presence of histopathological regression was more frequently associated with tumors that had precise margins, absent vascularization and with those that did not have ulceration on US. The high mitotic rate was associated with tumors that presented imprecise margins, increased vascularization and US detectable ulceration.

Conclusion

Innovative CM diagnosis using non-invasive methods like dermoscopy and ultrasound may enhance accuracy and treatment guidance by assessing lesion characteristics.

In vivo Raman spectroscopic and fluorescence study of suspected melanocytic lesions and surrounding healthy skin

Cutaneous melanoma is the most lethal skin cancer and noninvasively distinguishing it from benign tumor is a major challenge. Raman spectroscopic measurements were conducted on 65 suspected melanocytic lesions and surrounding healthy skin from 47 patients. Compared to the spectra of healthy skin, spectra of melanocytic lesions exhibited lower intensities in carotenoid bands and higher intensities in lipid and melanin bands, suggesting similar variations in the content of these components. Distinct variations were observed among the autofluorescence intensities of healthy skin, benign nevi and malignant melanoma. By incorporating autofluorescence information, the classification accuracy of the support vector machine for spectra of healthy skin, nevi, and melanoma reached 90.2%, surpassing the 87.9% accuracy achieved without autofluorescence, with this difference being statistically significant. These findings indicate the diagnostic value of autofluorescence intensity, which reflect differences in fluorophore content, chemical composition, and structure among healthy skin, nevi, and melanoma.

High-frequency ultrasound accuracy in preoperative cutaneous melanoma assessment: A meta-analysis

BACKGROUND

High-frequency ultrasound (HFUS) can safely and efficiently visualize cutaneous tumour characteristics including depth.

OBJECTIVES

We aimed to evaluate its accuracy in measuring melanoma depth against the gold standard, histopathology, for treatment planning.

METHODS

A review of publications was conducted in March 2023 through five electronic databases. Thirty-six included articles studied patients who received HFUS (≥10 MHz) measurements, melanoma biopsy or excision, and reported a tumour depth correlation coefficient between HFUS and histopathology. We analysed correlation coefficients between HFUS and histopathology, measured tumour depths and shed light on reasons for mismeasurements. Additionally, we identified the reporting of critical metrics including, lesion characteristics, melanoma subtype, type of correlation coefficient, 95% confidence intervals for Pearson coefficients and sample size.

RESULTS

The most common tumour imaged was superficial spreading melanoma on the trunk and extremities, followed by head/face. Maximum ultrasound frequencies ranged from 13 MHz to 100 MHz with participants ranging from 5 to 264. Histopathology and HFUS correlation coefficients ranged from 0.417 to 0.997 (median: 0.94, mean: 0.89 and SD: 0.13). Lower frequency probes (10-20 MHz) were less accurate in assessing melanoma thickness, with a cumulative mean correlation coefficient of 0.87 compared to 0.94 (20-25 MHz) and 0.98 (≥70 MHz). Studies demonstrated higher sonographic accuracy in melanomas >0.75 mm. Additionally, ultrasound may report increased melanoma depth compared to histopathology for reasons including lymphocytic infiltration, presence of a nevus and shrinkage during specimen processing. Furthermore, we found a gap in the reporting of details such as fundamental characteristics of lesion populations. Specifically, 86% (31 out of 36) of the studies failed to report one or more critical metrics, such as mean, median or range of lesion depths.

CONCLUSIONS

HFUS may serve as a supplementary tool for preoperative melanoma assessment, with increased accuracy in thicker tumours. Frequencies <20 MHz are less reliable in assessing depth. Frequencies ≥70 MHz demonstrate stronger correlations to histopathology. Higher ultrasound accuracy was seen for melanomas with Breslow depth >0.75 mm.

Diagnostic accuracy of high-frequency ultrasound for cutaneous neoplasms: a narrative review of the literature

High-frequency ultrasound has been used to visualize depth and vascularization of cutaneous neoplasms, but little has been synthesized as a review for a robust level of evidence about the diagnostic accuracy of high-frequency ultrasound in dermatology. A narrative review of the PubMed database was performed to establish the correlation between ultrasound findings and histopathologic/dermoscopic findings for cutaneous neoplasms. Articles were divided into the following four categories: melanocytic, keratinocytic/epidermal, appendageal, and soft tissue/neural neoplasms. Review of the literature revealed that ultrasound findings and histopathology findings were strongly correlated regarding the depth of a cutaneous neoplasm. Morphological characteristics were correlated primarily in soft tissue/neural neoplasms. Overall, there is a paucity of literature on the correlation between high-frequency ultrasound and histopathology of cutaneous neoplasms. Further studies are needed to investigate this correlation in various dermatologic conditions.

Non-invasive 3D imaging of human melanocytic lesions by combined ultrasound and photoacoustic tomography: a pilot study

The accurate determination of the size and depth of infiltration is critical to the treatment and excision of melanoma and other skin cancers. However, current techniques, such as skin biopsy and histological examination, pose invasiveness, time-consumption, and have limitations in measuring at the deepest level. Non-invasive imaging techniques like dermoscopy and confocal microscopy also present limitations in accurately capturing contrast and depth information for various skin types and lesion locations. Thus, there is a pressing need for non-invasive devices capable of obtaining high-resolution 3D images of skin lesions. In this study, we introduce a novel device that combines 18 MHz ultrasound and photoacoustic tomography into a single unit, enabling the acquisition of colocalized 3D images of skin lesions. We performed in vivo measurements on 25 suspicious human skin nevi that were promptly excised following measurements. The combined ultrasound/photoacoustic tomography imaging technique exhibited a strong correlation with histological Breslow thickness between 0.2 and 3 mm, achieving a coefficient of determination (R[Formula: see text]) of 0.93, which is superior to the coefficients from the individual modalities. The results procured in our study underscore the potential of combined ultrasound and photoacoustic tomography as a promising non-invasive 3D imaging approach for evaluating human nevi and other skin lesions. Furthermore, the system allows for integration of other optical modalities such as optical coherence tomography, microscopy, or Raman spectroscopy in future applications.

Combined ultrasound and photoacoustic C-mode imaging system for skin lesion assessment

Accurate assessment of the size and depth of infiltration is critical for effectively treating and removing skin cancer, especially melanoma. However, existing methods such as skin biopsy and histologic examination are invasive, time-consuming, and may not provide accurate depth results. We present a novel system for simultaneous and co-localized ultrasound and photoacoustic imaging, with the application for non-invasive skin lesion size and depth measurement. The developed system integrates an acoustical mirror that is placed on an ultrasound transducer, which can be translated within a flexible water tank. This allows for 3D (C-mode) imaging, which is useful for mapping the skin structure and determine the invasion size and depth of lesions including skin cancer. For efficient reconstruction of photoacoustic images, we applied the open-source MUST library. The acquisition time per 2D image is <1 s and the pulse energies are below the legal Maximum Permissible Exposure (MPE) on human skin. We present the depth and resolution capabilities of the setup on several self-designed agar phantoms and demonstrate in vivo imaging on human skin. The setup also features an unobstructed optical window from the top, allowing for simple integration with other optical modalities. The perspective towards clinical application is demonstrated.

Ultra-High Frequency Ultrasound in Melanoma Management: A New Combined Ultrasonographic-Histopathological Approach

OBJECTIVES

The main aim of this study is to evaluate the correspondence between the ultrasonographic thickness and the Breslow thickness in melanoma using ultra-high frequency ultrasound and the intra- and inter-operator repeatability in the ultrasonographic measurements of melanoma depth. Moreover, we propose a new protocol based on a combined ultrasonographic-histopathological approach.

METHODS

We analyzed 27 melanomas in a population consisted of 27 patients (mean age 57.6 years, 51.8% males), who came at the Department of Dermatology (University of Pisa, Pisa, Italy) from April 2016 to March 2018 and had an ultrasonographic examination of a suspected lesion before the surgical removal using ultra-high frequency ultrasound (Vevo®MD, Fujifilm, Visualsonics, Toronto, Canada; 70 MHz probe). B-mode images were analyzed by two skilled and blinded operators, and the maximum depth of the lesions was measured using a dedicated graphical user interface developed in Matlab R2016b (MathWorks Inc., Natick, MA), to obtain repetitive measurements.

RESULTS

All melanomas appeared as band-like or oval/fusiform shaped hypoechoic inhomogeneous lesions. We observed an excellent agreement between the Breslow thickness of melanomas and the ultrasonographic thickness, as well as a reduced intra- and inter-operator variability in the ultrasonographic measurements of melanoma depth.

CONCLUSIONS

We propose a ultrasonographic-histopathological protocol which may help clinicians to reduce the diagnostic delay, improve prognosis and survival rates, perform a surgical excision with negative margins, and reduce the variability in the assessment of Breslow thickness.

Multimodal system for optical biopsy of melanoma with integrated ultrasound, optical coherence tomography and Raman spectroscopy

We introduce a new single-head multimodal optical system that integrates optical coherence tomography (OCT), 18 MHz ultrasound (US) tomography and Raman spectroscopy (RS), allowing for fast (<2 min) and noninvasive skin cancer diagnostics and lesion depth measurement. The OCT can deliver structural and depth information of smaller skin lesions (<1 mm), while the US allows to measure the penetration depth of thicker lesions (≥4 mm), and the RS analyzes the chemical composition from a small chosen spot (≤300 μm) that can be used to distinguish between benign and malignant melanoma. The RS and OCT utilize the same scanning and optical setup, allowing for co-localized measurements. The US on the other side is integrated with an acoustical reflector, which enables B-mode measurements on the same position as OCT and RS. The US B-mode scans can be translated across the sample by laterally moving the US transducer, which is made possible by the developed adapter with a flexible membrane. We present the results on custom-made liquid and agar phantoms that show the resolution and depth capabilities of the setup, as well as preliminary ex vivo measurements on mouse models with ∼4.3 mm thick melanoma.

Clinical application of ultra-high frequency ultrasound: Discovering a new imaging frontier

The ultra-high frequency ultrasound (UHFUS) is characterized by the use of probes between 30 and 100 MHz. This technology has recently been introduced in clinical practice and represents an opportunity for the diagnosis of numerous pathologies. The high spatial resolution of UHFUS, up to 30 μ in pixel size, allows to study the pathological modifications and to guide microsurgery treatments in anatomical body structures not evaluable by conventional HFUS. The aim of this work is to provide a review of the literature on the current clinical applications of UHFUS and to discuss its added role in different clinical settings.

Self-made transparent optoacoustic detector for measurement of skin lesion thicknessin vivo

In skin cancer diagnosis and treatment, one of the key factors is tumor depth, which is connected to the severity and the required excision depth. Optoacoustical (OA) imaging is a relatively popular technique that provides information based on the optical absorption of the sample. Although often demonstrated withex vivomeasurements orin vivoimaging on parts of small animals,in vivomeasurements on humans are more challenging. This is presumably because it is too time consuming and the required excitation pulse energies and their number exceed the allowed maximum permissible exposure (MPE). Here, we demonstrate thickness measurements with a transparent optoacoustical detector of different suspicious skin lesionsin vivoon patients. We develop the signal processing technique to automatically convert the raw signal into thickness via deconvolution with the impulse response function. The transparency of the detector allows optical excitation with the pulsed laser to be performed perpendicularly on the lesion, in contrast to the conventional illumination from the side. For validation, the measured results were compared to the histological thickness determined after excision. We show that this simple transparent detector allows to determine the thickness of a lesion and thus, aid the dermatologist to estimate the excision depth in the future.

Wavefront Shaping Concepts for Application in Optical Coherence Tomography-A Review

Optical coherence tomography (OCT) enables three-dimensional imaging with resolution on the micrometer scale. The technique relies on the time-of-flight gated detection of light scattered from a sample and has received enormous interest in applications as versatile as non-destructive testing, metrology and non-invasive medical diagnostics. However, in strongly scattering media such as biological tissue, the penetration depth and imaging resolution are limited. Combining OCT imaging with wavefront shaping approaches significantly leverages the capabilities of the technique by controlling the scattered light field through manipulation of the field incident on the sample. This article reviews the main concepts developed so far in the field and discusses the latest results achieved with a focus on signal enhancement and imaging.

The Application of Ultra-High-Frequency Ultrasound in Dermatology and Wound Management

The management of lower extremity wounds is frequently performed by means of clinical examination, representing a challenge for the clinician due to the various conditions that can potentially enter differential diagnosis. Several diagnostic techniques are available in the dermatologist’s arsenal as a support to diagnosis confirmation, including dermoscopy and ultrasonography. Recently, a novel ultrasonographic technique involving the use of ultra-high ultrasound frequencies has entered the scene, and appears a promising tool in the diagnostic workup of skin ulcerative lesions. The focus of this review is to discuss the potential role of ultra-high-frequency ultrasonography in the diagnostic workup of wounds in the light of the current applications of the technique.

Ultra-High Frequency Ultrasound, A Promising Diagnostic Technique: Review of the Literature and Single-Center Experience

OBJECTIVES

Ultra-high frequency ultrasonography (UHFUS) is a recently introduced diagnostic technique which finds several applications in diverse clinical fields. The range of frequencies between 30 and 100 MHz allows for high spatial resolution imaging of superficial structures, making this technique suitable for the imaging of skin, blood vessels, musculoskeletal anatomy, oral mucosa, and small parts. However, the current clinical applications of UHFUS have never been analyzed in a consistent multidisciplinary manner. The aim of this study is to revise and discuss the current applications of UHFUS in different aspects of research and clinical practice, as well as to provide some examples of the current work-in-progress carried out in our center.

MATERIALS AND METHODS

A literature search was performed in order to retrieve articles reporting the applications of UHFUS both in research and in clinical settings. Inclusion criteria were the use of frequencies above 30 MHz and study design conducted in vivo on human subjects.

RESULTS

In total 66 articles were retrieved. The majority of the articles focused on dermatological and vascular applications, although musculoskeletal and intraoral applications are emerging fields of use. We also describe our experience in the use of UHFUS as a valuable diagnostic support in the fields of dermatology, rheumatology, oral medicine, and musculoskeletal anatomy.

CONCLUSION

Ultra-high frequency ultrasonography application involves an increasing number of medical fields. The high spatial resolution and the superb image quality achievable allow to foresee a wider use of this novel technique, which has the potential to bring innovation in diagnostic imaging.

Imaging findings of Bowen's disease: A comparison between ultrasound biomicroscopy and conventional high-frequency ultrasound

OBJECTIVES

To compare the imaging findings of Bowen's disease (BD) between ultrasound biomicroscopy (UBM) and conventional high-frequency ultrasound (HFUS).

METHODS

A total of 29 pathologically proven BD lesions in 28 patients were retrospectively enrolled in the study, and all were after surgery. All the lesions were imaged with both UBM and HFUS. The imaging features on HFUS and UBM were analyzed and compared. The diagnostic results of ultrasound for BD were referenced with pathology results.

RESULTS

All the 29 (100%) BD lesions appeared hypoechogenicity, solid component, and superficial hyperechoic layer (ie, keratinization) on both UBM and HFUS. The typical imaging feature of BD lesions, that was, infiltration depth confined to the epidermis, was visualized in 25 (86.2%, 25/29) lesions on UBM whereas 15 (51.7%, 15/29) on HFUS (P = .002). A "wave sign," which corresponds to the surface keratinization of BD lesion, was visualized in 17 (58.6%, 17/29) of BD lesions on UBM whereas 6 (20.7%, 6/29) on HFUS (P = .001). UBM and HFUS correctly diagnosed 25 (86.2%, 25/29) and 15 (51.7%, 15/29) BD lesions, respectively (P = .002).

CONCLUSIONS

Bowen's disease has some typical imaging features on US. The "wave sign" of the superficial hyperechoic layer and the clear borderline between the tumor in epidermis and the slightly hyperechoic dermis layer are better depicted by UBM in comparison with HFUS, which leads to a more accurate diagnosis of BD. UBM has potential to be used as a diagnostic tool for characterization of BD on account of its high resolution.

Cutaneous optical coherence tomography for longitudinal volumetric assessment of intradermal volumes in a mouse model

Clinical evaluation of skin lesions requires precise and reproducible technologies for their qualitative and quantitative assessment. In this study, we investigate the applicability of a custom-built dermatologic OCT system for longitudinal assessment of intradermal volumes in a mouse model. The OCT, based on an akinetic swept laser working at 1310 nm was employed for visualization and quantification of intradermal deposits of three different hyaluronic acid-based hydrogel formulations - one commercial and two test substances. Hydrogels were applied in 22 BALB/c mice, and measurements were performed over a six-month time period. All hydrogels increased in volume within the first weeks and degraded steadily thereafter. The half-lifes of the test hydrogels (27.2 ± 13.6 weeks for Hydrogel 1, 31.5 ± 17.2 weeks for Hydrogel 2) were higher in comparison to the commercially available HA hydrogel (21.4 ± 12.0 weeks), although differences were not significant. The sphericity parameter was used for evaluation of the deposit geometry. While on the injection day the sphericities were similar (~0.75 ± 0.04), at later time points significant differences between the different test substances were found (T24: PRV 0.59 ± 0.09, Hydrogel 1 0.70 ± 0.11, Hydrogel 2 0.78 ± 0.07; p ≤ 0.012 for all pairs). This study shows the applicability of OCT imaging for quantitative assessment of the volumetric behavior of intradermal deposits in vivo.

The potential role of using vaccine patches to induce immunity: platform and pathways to innovation and commercialization

Introduction: In the last two decades, the evidence related to using vaccine patches with multiple short projections (≤1 mm) to deliver vaccines through the skin increased significantly and demonstrated their potential as an innovative delivery platform.Areas covered: We review the vaccine patch literature published in English as of 1 March 2019, as well as available information from key stakeholders related to vaccine patches as a platform. We identify key research topics related to basic and translational science on skin physical properties and immunobiology, patch development, and vaccine manufacturing.Expert opinion: Currently, vaccine patch developers continue to address some basic science and other platform issues in the context of developing a potential vaccine patch presentation for an existing or new vaccine. Additional clinical data and manufacturing experience could shift the balance toward incentivizing existing vaccine manufactures to further explore the use of vaccine patches to deliver their products. Incentives for innovation of vaccine patches differ for developed and developing countries, which will necessitate different strategies (e.g. public-private partnerships, push, or pull mechanisms) to support the basic and applied research needed to ensure a strong evidence base and to overcome translational barriers for vaccine patches as a delivery platform.

Comparison of optical coherence tomography and high frequency ultrasound imaging in mice for the assessment of skin morphology and intradermal volumes

Optical coherence tomography (OCT) and high-frequency ultrasound (HFUS), two established imaging modalities in the field of dermatology, were evaluated and compared regarding their applicability for visualization of skin tissue morphology and quantification of murine intradermal structures. The accuracy and reproducibility of both methods were assessed ex vivo and in vivo using a standardized model for intradermal volumes based on injected soft tissue fillers. OCT revealed greater detail in skin morphology, allowing for detection of single layers due to the superior resolution. Volumetric data measured by OCT (7.9 ± 0.3 μl) and HFUS (7.7 ± 0.5 μl) were in good agreement and revealed a high accuracy when compared to the injected volume of 7.98 ± 0.8 µl. In vivo, OCT provided a higher precision (relative SD: 26% OCT vs. 42% HFUS) for the quantification of intradermal structures, whereas HFUS offered increased penetration depth enabling the visualization of deeper structures. A combination of both imaging technologies might be valuable for tumor assessments or other dermal pathologies in clinical settings.

Ultrasound Biomicroscopy and High-Frequency Ultrasound for Evaluating Extramammary Paget Disease With Pathologic Correlation

OBJECTIVES

The purpose of this study was to investigate the performance of ultrasound biomicroscopy (UBM) and high-frequency ultrasound (HFUS) in the assessment of extramammary Paget disease (EMPD) and to correlate the imaging features with pathologic findings.

METHODS

In this retrospective study, we described the imaging features from UBM and HFUS based on 17 pathologically proven EMPD cases. The performance for visualizing layer involvement by UBM and HFUS was compared. Additionally, we checked the consistency between layer involvement of the lesions on UBM images and the pathologic results. Additionally, blood flow and the status of lymph nodes were investigated with HFUS.

RESULTS

Ultrasound biomicroscopy revealed that all 17 lesions (100%) were hypoechoic and grew in a creeping form. The feature of layer involvement was shown in 10 lesions (58.8%) limited to the epidermis and 6 lesions (35.3%) involving the dermis, and the remaining lesion (5.9%) involved the full skin layers. Layer involvement was clearly displayed by UBM for all lesions (100%) but for only 5 lesions (29.4%) by HFUS (P < .001). Additionally, the layer involvement of 15 lesions (88.2%) on UBM was consistent with the pathologic results (κ = 0.746). High-frequency ultrasound revealed profuse blood flow in most lesions (64.7% [11 of 17]), and 1 case showed inguinal lymph node metastasis.

CONCLUSIONS

Combined use of UBM and HFUS can provide key information on EMPD based on ultrasound features. Comparatively, UBM provides clearer morphologic information, whereas HFUS provides information on lymph node metastasis and blood flow.

Non-Contact Dermatoscope with Ultra-Bright Light Source and Liquid Lens-Based Autofocus Function

Dermatoscopes are routinely used in skin cancer screening but are rarely employed for the diagnosis of other skin conditions. Broader application is promising from a diagnostic point of view as biopsies for differential diagnosis may be avoided but it requires non-contact devices allowing a comparably large field of view that are not commercially available today. Autofocus and color reproducibility are specific challenges for the development of dermatoscopy for application beyond cancer screening. We present a prototype for such a system including solutions for autofocus and color reproducibility independent of ambient lighting. System performance includes sufficiently high feature resolution of up to 30 µm and feature size scaling fulfilling the requirements to apply the device in regular skin cancer screening.

Raman Sensing and Its Multimodal Combination with Optoacoustics and OCT for Applications in the Life Sciences

Currently, many optical modalities are being investigated, applied, and further developed for non-invasive analysis and sensing in the life sciences. To befit the complexity of the study objects and questions in this field, the combination of two or more modalities is attempted. We review our work on multimodal sensing concepts for applications ranging from non-invasive quantification of biomolecules in the living organism to supporting medical diagnosis showing the combined capabilities of Raman spectroscopy, optical coherence tomography, and optoacoustics.

Single Transparent Piezoelectric Detector for Optoacoustic Sensing-Design and Signal Processing

In this article, we present a simple and intuitive approach to create a handheld optoacoustic setup for near field measurements. A single piezoelectric transducer glued in between two sheets of polymethyl methacrylate (PMMA) facilitates nearfield depth profiling of layered media. The detector electrodes are made of indium tin oxide (ITO) which is both electrically conducting as well as optically transparent, enabling an on-axis illumination through the detector. By mapping the active detector area, we show that it matches the design form precisely. We also present a straightforward approach to determine the instrument response function, which allows to obtain the original pressure profile arriving at the detector. To demonstrate the validity of this approach, the measurement on a simple test sample is deconvolved with the instrument response function and compared to simulation results. Except for the sputter instrumentation, all required materials and instruments as well as the tools needed to create such a setup are available to standard scientific laboratories.

Iterative wavefront correction for complex spectral domain optical coherence tomography

We propose a compact setup for wavefront manipulation in spectral domain optical coherence tomography (OCT). The system can easily be implemented into existing free-space OCT setups through modification of the source path only. We demonstrate complex-valued OCT signal acquisition based on phase shifting combined with iterative optical wavefront shaping, which locally enhances the OCT signal acquired from within a scattering sample. The system lends itself to future imaging studies in strongly scattering media such as biological tissue.

Trimodal system for in vivo skin cancer screening with combined optical coherence tomography-Raman and colocalized optoacoustic measurements

A new multimodal system for rapid, noninvasive in vivo skin cancer screening is presented, combining optical coherence tomography (OCT) and optoacoustic (OA) modalities to provide precise tumor depth determination with a Raman spectroscopic modality capable of detecting the lesion type and, thus, providing diagnostic capability. Both OA and Raman setups use wide field skin illumination to ensure the compliance with maximum permissible exposure (MPE) requirements. The Raman signal is collected via the OCT scanning lens to maximize the signal-to-noise ratio of the measured signal while keeping radiation levels below MPE limits. OCT is used to optically determine the tumor thickness and for volumetric imaging whereas OA utilizes acoustic signals generated by optical absorption contrast for thickness determination at potentially higher penetration depths compared to OCT. Preliminary results of first clinical trials using our setup are presented. The measured lesion depth is in good agreement with histology results, while Raman measurements show distinctive differences between normal skin and melanocytic lesions, and, moreover, between different skin areas. In future, we will validate the setup presented for reliable detection of pathophysiological parameters, morphology and thickness of suspicious skin lesions.

Ultrasound and Infrared-Based Imaging Modalities for Diagnosis and Management of Cutaneous Diseases

Non-invasive bedside imaging tools are becoming more prevalent for assessing cutaneous lesions. Ultrasound used at specific frequencies allows us to assess margins of lesions to minimize the extent of the biopsy that is performed and improve cosmetic outcomes. Vascularity, seen on Doppler ultrasound and contrast-enhanced ultrasound, and stiffness, assessed on tissue elastography, can help differentiate between benign and malignant lesions for clinicians to be more judicious in deciding whether to biopsy. Moreover, research has shown the efficacy in using ultrasound in monitoring flares of hidradenitis suppurativa, a disease affecting apocrine gland-rich areas of the body, for which the current gold standard involves examining and scoring inflammatory lesions with the naked eye. Infrared-based modalities have also been on the uptrend to aid in clinical decision-making regarding suspiciousness of lesions. Reflectance confocal microscopy has lateral resolution that is comparable to histopathology and it has been shown to be an appropriate adjunctive tool to dermoscopy, specifically when evaluating melanomas. Optical coherence tomography has utility in determining lesion thickness because of its depth penetration, and spectrophotometric intracutaneous analysis is becoming more popular as a tool that can be used by general practitioners to know when to refer to dermatology regarding worrisome pigmented lesions. Strides have been made to incorporate electrical impedance spectroscopy alongside dermoscopy in decision-making regarding excision, although the evidence for its use in the clincial setting remains inconclusive. This paper reviews the efficacy and drawbacks of these techniques in the field of dermatology and suggests future directions.

One Step Surgery for Cutaneous Melanoma: "We Cannot Solve Our Problems with the Same Thinking We Used When We Created Them?"

One step melanoma surgery is, in fact, an innovative combined method for diagnosis and treatment of cutaneous melanoma (at the same time). The methodology allows an accurate assessment of the actual status of the affected patients by 1) clinical status, dermatoscopy, high-frequent ultrasonography (HFUS) of the pigmented lesion (eventually in combination with normal lymph nodes ultrasonography), followed by a single surgical intervention. Within this intervention, the primary tumour is removed with the appropriate surgical field, with or without parallel detection and draining lymph node biopsy (depending on the established tumour thickness). Removal of the lymph node may, in turn, be associated with or without locoregional lymphadenectomy, which is determined by its macroscopic appearance, established intraoperatively or after the histopathological evaluation. The methodology is sparing, innovative, easy to apply, tested in its functionality and logically justified. For an unknown reason, this methodology is not applicable in melanoma treatment’s guidelines in Europe and America. In Bulgaria and France, however, there are centres and hospitals that apply the technique mentioned above with enormous results, in particular in Bulgaria, the methodology is getting more and more improved to the current moment. Based on the above, as well as on the scant experience, we may share the opinion that the current melanoma treatment’s guidelines need major corrections in their recommendations, which are not optimal for patients due to the following facts: (1) the adverse effects on patients as a result of the necessity of at least 2 surgical interventions; (2) the frequent occurrence of changes in the lymph flow after the primary excision; (3) the frequent non-obtaining of the suggested in the guidelines terms for re-excisions with or without sentinel lymph node removal; and (4) the creation of additional financial difficulties for the patients in the framework of two unneeded hospitalizations.

Development of a combined OCT-Raman probe for the prospective in vivo clinical melanoma skin cancer screening

A combined optical coherence tomography (OCT)-Raman probe was designed and built into a spectral domain OCT head, and its performance was evaluated and compared to the most common Raman probe setups, based on a fiber bundle and confocal free space optics. Due to the use of the full field of view of an OCT scanning lens, the combined probe has a superior performance within maximum permissible exposure limits, compared to the other two probes. Skin Raman spectra, recorded in vivo, further prove the feasibility of the OCT-Raman probe for the future in vivo clinical applications in skin cancer screening.