Combined reflectance confocal microscopy-optical coherence tomography for delineation of basal cell carcinoma margins: an ex vivo study

One-Stop Shop: Diagnosis and Treatment of Basal Cell Carcinoma in One Step

Monitoring the tumor margins of basal cell carcinomas is still a challenge in everyday clinical practice. Usually, the clinical margins of the tumor are marked by the naked eye or, even better, with dermoscopy before surgery and then examined in detail after the operation using histological examination. In order to achieve tumor freedom, several surgical steps are sometimes necessary, meaning that patients spend longer periods in hospital and the healthcare system is burdened more as a result. One way to improve this is the one-stop shop method, which requires precise diagnostics and margin marking before and during surgery so that tumor freedom can be achieved after just one surgery. For this reason, the current status of the diagnosis and treatment of basal cell carcinomas before and after surgery is to be examined following extensive literature research using devices and methods that have already been tested in order to determine how a simplified process of tumor margin control of basal cell carcinomas can be made possible both in vivo and ex vivo.

'Pitfalls for differentiating basal cell carcinoma from non-basal cell carcinoma on optical coherence tomography: A clinical series'

Optical coherence tomography (OCT), a non-invasive diagnostic modality, may replace biopsy for diagnosing basal cell carcinoma (BCC) if a high-confidence BCC diagnosis can be established. In other cases, biopsy remains necessary to establish a histopathological diagnosis and treatment regimen. It is, therefore, essential that OCT assessors have a high specificity for differentiating BCC from non-BCC lesions. To establish high-confidence BCC diagnoses, specific morphological BCC characteristics on OCT are used. This study aimed to review several cases of non-BCC lesions that were misclassified as BCC by experienced OCT assessors, thereby providing insight into the causes of these misclassifications and how they may be prevented. The study population consisted of patients who had a histopathologically-verified non-BCC lesion. Patients from Maastricht University Medical Center+ from February 2021 to April 2021 were included in the study. Two independent OCT assessors assessed OCT scans. One OCT assessor recorded the presence or absence of validated morphological BCC characteristics. A false-positive OCT test result was defined as certainty of BCC presence in a non-BCC lesion. The frequency of misclassifications and the presence or absence of morphological BCC features are discussed. A total of 124 patients with non-BCC lesions were included. Six patients were misclassified by both OCT assessors and are discussed in more detail. Histopathological diagnoses were squamous cell carcinoma (n = 2/21), actinic keratosis (n = 2/29), squamous cell carcinoma in situ/Bowen's disease (n = 1/16), or interphase dermatitis (n = 1/4). In all misclassified cases, multiple, apparent morphological BCC characteristics on OCT were present. Most non-BCC lesions are recognized as such by OCT assessors. However, there remains a small risk that a high-confidence BCC diagnosis is established in non-BCC lesions wherein features mimicking validated BCC characteristics are present. Misclassification may be prevented by careful delineation of epidermal layers and good differentiation between dermal ovoid structures typical of BCC versus squamous cell carcinoma.

Non-invasive, in vivo, characterization of cutaneous metastases using a novel multimodal RCM-OCT imaging device: a case-series

BACKGROUND

Cutaneous metastases (CM) diagnosis is clinically challenging, requiring an invasive biopsy for confirmation. A novel, RCM-OCT device combines the advantage of horizontal high-resolution reflectance confocal microscopy (RCM) images and vertical deeper optical coherence tomography (OCT) images to aid in non-invasive diagnosis of CM from breast cancers.

OBJECTIVE

Characterize CM from breast cancers using RCM-OCT device.

METHODS

Seven patients suffering from breast cancers with suspicious CM were consented and imaged with RCM-OCT device. CM features were defined by comparing with histopathology. Tumour depths were measured on OCT and on H&E-images and correlated using statistical analysis Pearson test. 3D-OCT images were reconstructed to enhance tumour visualization.

RESULTS

6/7 lesions were CM from breast cancers, and one was vascular ectasia, on histopathology. CM appeared as greyish-darkish oval to round structures within the dermis on RCM and OCT-images. On RCM, individual tumour cells were seen, enabling identification of even small tumour foci; while, on OCT deeper tumours were detected. Inflammatory cells, dilated vessels and coarse collagen were identified in the dermis. Pearson correlation had an r2 of 0.38 and a significant P-value <0.004 for depth measurements. CM from breast cancers could be differentiated from ecstatic vessels on 3D-reconstructed OCT image.

LIMITATION

Small sample size and lack of clinical mimickers.

CONCLUSION

RCM-OCT can detect CM and has potential in aiding non-invasive diagnosis and management.

Optical Microscopy Systems for the Detection of Unlabeled Nanoparticles

Label-free detection of nanoparticles is essential for a thorough evaluation of their cellular effects. In particular, nanoparticles intended for medical applications must be carefully analyzed in terms of their interactions with cells, tissues, and organs. Since the labeling causes a strong change in the physicochemical properties and thus also alters the interactions of the particles with the surrounding tissue, the use of fluorescently labeled particles is inadequate to characterize the effects of unlabeled particles. Further, labeling may affect cellular uptake and biocompatibility of nanoparticles. Thus, label-free techniques have been recently developed and implemented to ensure a reliable characterization of nanoparticles.

This review provides an overview of frequently used label-free visualization techniques and highlights recent studies on the development and usage of microscopy systems based on reflectance, darkfield, differential interference contrast, optical coherence, photothermal, holographic, photoacoustic, total internal reflection, surface plasmon resonance, Rayleigh light scattering, hyperspectral and reflectance structured illumination imaging. Using these imaging modalities, there is a strong enhancement in the reliability of experiments concerning cellular uptake and biocompatibility of nanoparticles, which is crucial for preclinical evaluations and future medical applications.

Improved microscopy with ultraviolet surface excitation (MUSE) using high-index immersion illumination

Microscopy with ultraviolet surface excitation (MUSE) typically has an optical sectioning thickness significantly larger than standard physical sectioning thickness, resulting in increased background fluorescence and higher feature density compared to formalin-fixed, paraffin-embedded physical sections. We demonstrate that high-index immersion with angled illumination significantly reduces optical sectioning thickness through increased angle of refraction of excitation light at the tissue interface. We present a novel objective dipping cap and waveguide-based MUSE illuminator design with high-index immersion and quantify the improvement in optical sectioning thickness, demonstrating an e^-1 section thickness reduction to 6.67 µm in tissue. Simultaneously, the waveguide illuminator can be combined with high or low magnification objectives, and we demonstrate a 6 mm² field of view, wider than a conventional 10x pathology objective. Finally, we show that resolution and contrast can be further improved using deconvolution and focal stacking, enabling imaging that is robust to irregular surface profiles on surgical specimens.

Dual-mode line-field confocal optical coherence tomography for ultrahigh-resolution vertical and horizontal section imaging of human skin in vivo

Line-field confocal optical coherence tomography (LC-OCT) is a recently introduced technique for ultrahigh-resolution vertical section (B-scan) imaging of human skin in vivo. This work presents a new implementation of the LC-OCT technique to obtain horizontal section images (C-scans) in addition to B-scans. C-scan imaging is achieved with this dual-mode LC-OCT system using a mirror galvanometer for lateral scanning along with a piezoelectric chip for modulation of the interferometric signal. A quasi-identical spatial resolution of ∼ 1 µm is measured for both B-scans and C-scans. The images are acquired in both modes at a rate of 10 frames per second. The horizontal field of view of the C-scans is 1.2 × 0.5 mm², identical to the vertical field of view of the B-scans. The user can switch between the two modes by clicking a button. In vivo cellular-resolution imaging of human skin is demonstrated in both B-scan and C-scan modes, with the possibility to navigate within the skin tissues in real time.

Evaluation of a Combined Reflectance Confocal Microscopy-Optical Coherence Tomography Device for Detection and Depth Assessment of Basal Cell Carcinoma

Importance

The limited tissue sampling of a biopsy can lead to an incomplete assessment of basal cell carcinoma (BCC) subtypes and depth. Reflectance confocal microscopy (RCM) combined with optical coherence tomography (OCT) imaging may enable real-time, noninvasive, comprehensive three-dimensional sampling in vivo, which may improve the diagnostic accuracy and margin assessment of BCCs.

Objective

To determine the accuracy of a combined RCM-OCT device for BCC detection and deep margin assessment.

Design, Setting, and Participants

This pilot study was carried out on 85 lesions from 55 patients referred for physician consultation or Mohs surgery at Memorial Sloan Kettering Skin Cancer Center in Hauppauge, New York. These patients were prospectively and consecutively enrolled in the study between January 1, 2017, and December 31, 2017. Patients underwent imaging, with the combined RCM-OCT probe, for previously biopsied, histopathologically confirmed BCCs and lesions clinically or dermoscopically suggestive of BCC. Only patients with available histopathologic examination after imaging were included.

Main Outcomes and Measures

Improvements in sensitivity, specificity, and diagnostic accuracy for BCC using the combined RCM-OCT probe as well as the correlation between OCT-estimated depth and histopathologically measured depth were investigated.

Results

In total, 85 lesions from 55 patients (27 [49%] were female and 28 [51%] were male with a median [range] age of 59 [21-90] years) were imaged. Imaging was performed on 25 previously biopsied and histopathologically confirmed BCCs and 60 previously nonbiopsied but clinically or dermoscopically suspicious lesions. Normal skin and BCC features were correlated and validated with histopathologic examination. In previously biopsied lesions, residual tumors were detected in 12 of 25 (48%) lesions with 100% sensitivity (95% CI, 73.5%-100%) and 23.1% specificity (95% CI, 5.0%-53.8%) for combined RCM-OCT probe. In previously nonbiopsied and suspicious lesions, BCCs were diagnosed in 48 of 60 (80%) lesions with 100% sensitivity (95% CI, 92.6%-100%) and 75% specificity (95% CI, 42.8%-94.5%). Correlation was observed between depth estimated with OCT and depth measured with histopathologic examination: the coefficient of determination (R2) was 0.75 (R = 0.86; P < .001) for all lesions, 0.73 (R = 0.85; P < .001) for lesions less than 500 μm deep, and 0.65 (R = 0.43; P < .001) for lesions greater than 500 μm deep.

Conclusions and Relevance

Combined RCM-OCT imaging may be prospectively used to comprehensively diagnose lesions suggestive of BCC and triage for treatment. Further validation of this device must be performed on a larger cohort.

A Retrospective Study of the Diagnostic Accuracy of In Vivo Reflectance Confocal Microscopy for Basal Cell Carcinoma Diagnosis and Subtyping

Current national and European guidelines recommend distinct management approaches for basal cell carcinoma (BCC) based on tumor location, size, and histopathological subtype. In vivo reflectance confocal microscopy (RCM) is a non-invasive skin imaging technique which may change the diagnostic pathway for BCC patients. This study aimed to determine the sensitivity and specificity of RCM for BCC diagnosis, assess the predictive values of several confocal criteria in correctly classifying BCC subtypes, and evaluate the intraobserver reliability of RCM diagnosis for BCC. We conducted a retrospective study in two tertiary care centers in Bucharest, Romania. We included adults with clinically and dermoscopic suspect BCCs who underwent RCM and histopathological examination of excision specimens. For RCM examinations, we used the VivaScope 1500 and histopathology of the surgical excision specimen was the reference standard. Of the 123 cases included in the analysis, BCC was confirmed in 104 and excluded in 19 cases. RCM showed both high sensitivity (97.1%, 95% CI (91.80, 99.40)) and specificity (78.95%, 95% CI (54.43, 93.95)) for detecting BCC. Several RCM criteria were highly predictive for BCC subtypes: cords connected to the epidermis for superficial BCC, big tumor islands, peritumoral collagen bundles and increased vascularization for nodular BCC, and hyporefractile silhouettes for aggressive BCC. Excellent intraobserver agreement (κ = 0.909, p < 0.001) was observed. This data suggests that RCM could be used for preoperative diagnosis and BCC subtype classification in patients with suspected BCCs seen in tertiary care centers.

The use of in vivo reflectance confocal microscopy for the diagnosis of melanoma

INTRODUCTION

The use of reflectance confocal microscopy (RCM) for imaging the skin non-invasively raised constantly during the last decade. One of the main field of application is skin cancer diagnosis, and in particular melanoma diagnosis. Several studies have investigated the diagnostic accuracy of RCM as compared to dermoscopic examination, and its value in enhancing early diagnosis of dermoscopic difficult melanomas. Areas covered: The purpose of this paper was to review the principles behind RCM image acquisition as well as to describe and discuss key RCM features of melanoma. Moreover, we conducted a literature search in order to highlight the current available evidence about RCM sensitivity and specificity in the diagnosis of melanoma. Expert commentary: During the last decade, we assisted at the increasing interest in non invasive imaging tools for the diagnosis of skin cancer. RCM is one of the most studied of a series of diagnostic methods that are emerging in the field of melanoma imaging. Most probably in the future, RCM will be more frequently available in tertiary referral centres, thus the knowledge of the pros and contra of the tool and its clinical applicability is of upmost importance in order to allow correct referrals with the final aim of improving diagnostic accuracy.

The clinical usefulness of optical coherence tomography during cancer interventions

INTRODUCTION

Tumor detection and visualization plays a key role in the clinical workflow of a patient with suspected cancer, both in the diagnosis and treatment. Several optical imaging techniques have been evaluated for guidance during oncological interventions. Optical coherence tomography (OCT) is a technique which has been widely evaluated during the past decades. This review aims to determine the clinical usefulness of OCT during cancer interventions focussing on qualitative features, quantitative features and the diagnostic value of OCT.

METHODS

A systematic literature search was performed for articles published before May 2018 using OCT in the field of surgical oncology. Based on these articles, an overview of the clinical usefulness of OCT was provided per tumor type.

RESULTS

A total of 785 articles were revealed by our search, of which a total of 136 original articles were available for analysis, which formed the basis of this review. OCT is currently utilised for both preoperative diagnosis and intraoperative detection of skin, oral, lung, breast, hepatobiliary, gastrointestinal, urological, and gynaecological malignancies. It showed promising results in tumor detection on a microscopic level, especially using higher resolution imaging techniques, such as high-definition OCT and full-field OCT.

CONCLUSION

In the near future, OCT could be used as an additional tool during bronchoscopic or endoscopic interventions and could also be implemented in margin assessment during (laparoscopic) cancer surgery if a laparoscopic or handheld OCT device will be further developed to make routine clinical use possible.

Advances in the use of reflectance confocal microscopy in melanoma

In vivo reflectance confocal microscopy (RCM) is a noninvasive high-resolution skin imaging tool that has become an important adjunct to clinical exam, dermoscopy and histopathology assessment, in the diagnosis and management of melanoma. RCM generates a horizontal view of the skin, whereby cellular and subcellular (e.g., nuclei, melanophages, collagen) structures, to the level of the upper dermis, are projected onto a screen at near-histological resolution. Morphologic descriptors, standardized terminology, and diagnostic algorithms are well established for the RCM assessment of melanoma, melanocytic, and nonmelanocytic lesions. Clinical applications of RCM in melanoma are broad and include diagnosis, assessment of large lesions on cosmetically sensitive areas, directing areas to biopsy, delineating margins prior to surgery, detecting response to treatment and assessing recurrence. This review will provide an overview of RCM technology, findings by melanoma subtype, clinical applications, as well as explore the accuracy of RCM for melanoma diagnosis, pitfalls and emerging uses of this technology ex vivo.

Imaging in cutaneous surgery

Skin cancer is the most commonly diagnosed cancer in the USA. Mohs micrographic surgery is a microscopically controlled surgical technique that excises lateral and deep surgical margins while also sparing function and achieving a good cosmetic outcome. Given the increasing incidence in skin cancer worldwide and its associated treatment costs, techniques are being developed to improve the time and cost efficacy of this procedure. The use of noninvasive imaging, both in vivo and ex vivo, has the potential to increase efficiency of diagnosis and surgical management of skin cancers. These devices are useful in delineating lateral and deep tumor margins prior to surgery in vivo as well as to detect residual tumor ex vivo virtually in real time.

Diagnostic accuracy of confocal microscopy imaging vs. punch biopsy for diagnosing and subtyping basal cell carcinoma

Background

In vivo reflectance confocal microscopy (RCM) is a promising non‐invasive skin imaging technique that could facilitate early diagnosis of basal cell carcinoma (BCC) instead of routine punch biopsies. However, the clinical value and utility of RCM vs. a punch biopsy in diagnosing and subtyping BCC is unknown.

Objective

To assess diagnostic accuracy of RCM vs. punch biopsy for diagnosing and subtyping clinically suspected primary BCC.

Methods

A prospective, consecutive cohort of 100 patients with clinically suspected BCC were included at two tertiary hospitals in Amsterdam, the Netherlands, between 3 February 2015 and 2 October 2015. Patients were randomized between two test‐treatment pathways: diagnosing and subtyping using RCM imaging followed by direct surgical excision (RCM one‐stop‐shop) or planned excision based upon the histological diagnosis and subtype of punch biopsy (standard care). The primary outcome was the agreement between the index tests (RCM vs. punch biopsy) and reference standard (excision specimen) in correctly diagnosing BCC. The secondary outcome was the agreement between the index tests and reference standard in correctly identifying the most aggressive BCC subtypes.

Results

Sensitivity to detect BCC was similar for RCM and punch biopsy (100% vs. 93.94%), but a punch biopsy was more specific than RCM (79% vs. 38%). RCM expert evaluation for diagnosing BCC had a sensitivity of 100% and a specificity of 75%. The agreement between RCM and excision specimen in identifying the most aggressive BCC subtype ranged from 50% to 85% vs. 77% by a punch biopsy.

Conclusion

Reflectance confocal microscopy and punch biopsy have comparable diagnostic accuracy to diagnose and subtype BCC depending on RCM experience. Although experienced RCM users could accurately diagnose BCC at a distance, we found an important difference in subtyping BCC. Future RCM studies need to focus on diagnostic accuracy, reliability and specific criteria to improve BCC subtype differentiation.

Reflectance confocal microscopy-guided laser ablation of basal cell carcinomas: initial clinical experience

Laser ablation offers a procedure for precise, fast, and minimally invasive removal of superficial and early nodular basal cell carcinomas (BCCs). However, the lack of histopathological confirmation has been a limitation toward widespread use in the clinic. A reflectance confocal microscopy (RCM) imaging-guided approach offers cellular-level histopathology-like feedback directly on the patient, which may then guide and help improve the efficacy of the ablation procedure. Following an ex vivo benchtop study (reported in our earlier papers), we performed an initial study on 44 BCCs on 21 patients in vivo, using a pulsed erbium:ytterbium aluminum garnet laser and a contrast agent (aluminum chloride). In 10 lesions on six patients, the RCM imaging-guided detection of either presence of residual tumor or complete clearance was immediately confirmed with histopathology. Additionally, 34 BCCs on 15 patients were treated with RCM imaging-guided laser ablation, with immediate confirmation for clearance of tumor (no histopathology), followed by longer-term monitoring, currently in progress, with follow-up imaging (again, no histopathology) at 3, 6, and 18 months. Thus far, the imaging resolution appears to be sufficient and consistent for monitoring efficacy of ablation in the wound, both immediately postablation and subsequently during recovery. The efficacy results appear to be promising, with observed clearance in 19 cases of 22 cases with follow-ups ranging from 6 to 21 months. An additional 12 cases with 1 to 3 months of follow-ups has shown clearance of tumor but a longer follow-up time is required to establish conclusive results. Further instrumentation development will be necessary to cover larger areas with a more automatically controlled instrument for more uniform, faster, and deeper imaging of margins.

Handheld optical coherence tomography-reflectance confocal microscopy probe for detection of basal cell carcinoma and delineation of margins

We present a hand-held implementation and preliminary evaluation of a combined optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) probe for detecting and delineating the margins of basal cell carcinomas (BCCs) in human skin <italic<in vivo</italic<. A standard OCT approach (spectrometer-based) with a central wavelength of 1310 nm and 0.11 numerical aperture (NA) was combined with a standard RCM approach (830-nm wavelength and 0.9 NA) into a common path hand-held probe. Cross-sectional OCT images and enface RCM images are simultaneously displayed, allowing for three-dimensional microscopic assessment of tumor morphology in real time. Depending on the subtype and depth of the BCC tumor and surrounding skin conditions, OCT and RCM imaging are able to complement each other, the strengths of each helping overcome the limitations of the other. Four representative cases are summarized, out of the 15 investigated in a preliminary pilot study, demonstrating how OCT and RCM imaging may be synergistically combined to more accurately detect BCCs and more completely delineate margins. Our preliminary results highlight the potential benefits of combining the two technologies within a single probe to potentially guide diagnosis as well as treatment of BCCs.

Imaging In focus: Reflected light imaging: Techniques and applications

Reflectance imaging is a broad term that describes the formation of images by the detection of illumination light that is back-scattered from reflective features within a sample. Reflectance imaging can be performed in a variety of different configurations, such as confocal, oblique angle illumination, structured illumination, interferometry and total internal reflectance, permitting a plethora of biomedical applications. Reflectance imaging has proven indispensable for critical investigations into the safety and understanding of biomedically and environmentally relevant nano-materials, an area of high priority and investment. The non-destructive in vivo imaging ability of reflectance techniques permits alternative diagnostic strategies that may eventually facilitate the eradication of some invasive biopsy procedures. Reflectance can also provide additional structural information and clarity necessary in fluorescent based in vivo studies. Near-coverslip interrogation techniques, such as reflectance interferometry and total internal reflection, have provided a label free means to investigate cell-surface contacts, cell motility and vesicle trafficking in vivo and in vitro. Other key advances include the ability to acquire superresolution reflectance images providing increased spatial resolution.

Reflectance confocal microscopy of skin in vivo: From bench to bedside

Following more than two decades of effort, reflectance confocal microscopy (RCM) imaging of skin was granted codes for reimbursement by the US Centers for Medicare and Medicaid Services. Dermatologists in the USA have started billing and receiving reimbursement for the imaging procedure and for the reading and interpretation of images. RCM imaging combined with dermoscopic examination is guiding the triage of lesions into those that appear benign, which are being spared from biopsy, against those that appear suspicious, which are then biopsied. Thus far, a few thousand patients have been spared from biopsy of benign lesions. The journey of RCM imaging from bench to bedside is certainly a success story, but still much more work lies ahead toward wider dissemination, acceptance, and adoption. We present a brief review of RCM imaging and highlight key challenges and opportunities. The success of RCM imaging paves the way for other emerging optical technologies, as well-and our bet for the future is on multimodal approaches. Lasers Surg. Med. 49:7-19, 2017. © 2016 Wiley Periodicals, Inc.

Master/slave optical coherence tomography imaging of eyelid basal cell carcinoma

Optical coherence tomography (OCT) is fast emerging as an additional non-interventional modality for skin tumor detection and diagnosis. A master/slave flying spot OCT configuration was assembled to detect periocular basal cell carcinomas (BCC). A swept source at 1300 nm and sweeping speed of 50 kHz were used. A three-step process was involved. First, 384 channeled spectra using a mirror were stored for 384 optical path differences at the master stage. Then, the stored channeled spectra (masks) were correlated with the channeled spectrum from the BCC tissue to produce 384 en face OCT images (200×200 pixels) for the optical path difference values used to acquire the masks. Finally, these en face slices were stacked to form a volume to cross-reference BCC tumor margins in the orthogonal plane. Per each eyelid sample, several en face images of 200×200 lateral pixels are produced in the time to scan laterally a complete raster of 1.6 s. Combination of the en face views with the cross-sectioning views allow for better discrimination of BCCs comparable to using cross-sectional imaging alone, as previously reported using the conventional fast-Fourier-transform-based OCT techniques.