Jean-Luc Perrot

Diagnostic Accuracy of Line-Field Confocal Optical Coherence Tomography for the Diagnosis of Skin Carcinomas

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Line-field confocal optical coherence tomography (LC-OCT) is a new, noninvasive imaging technique for the diagnosis of skin cancers. A total of 243 benign (54%) and malignant (46%) skin lesions were consecutively enrolled from 27 August 2020, to 6 October 2021 at the Dermatology Department of the University Hospital of Siena, Italy. Dermoscopic- and LC-OCT-based diagnoses were given by an expert dermatologist and compared with the ground truth. Considering all types of malignant skin tumours (79 basal cell carcinomas (BCCs), 22 squamous cell carcinomas, and 10 melanomas), a statistically significant increase (p = 0.013) in specificity was observed from dermoscopy (0.73, CI 0.64–0.81) to LC-OCT (0.87, CI 0.79–0.93) while sensitivity was the same with the two imaging techniques (0.95 CI 0.89–0.98 for dermoscopy and 0.95 CI 0.90–0.99 for LC-OCT). The increase in specificity was mainly driven by the ability of LC-OCT to differentiate BCCs from other diagnoses. In conclusion, our real-li...

Comparison of reflectance confocal microscopy and line-field optical coherence tomography for the identification of keratinocyte skin tumours

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Background: Reflectance confocal microscopy (RCM) and line-field confocal optical coherence tomography (LC-OCT) are non-invasive imaging devices that can help in the clinical diagnosis of actinic keratosis (AK) and cutaneous squamous cell carcinoma (SCC). No studies are available on the comparison between these two technologies for the identification of the different features of keratinocyte skin tumours. Objectives: To compare RCM and LC-OCT findings in AK and SCC. Methods: A retrospective multicenter study was conducted. Tumours were imaged with RCM and LC-OCT devices before surgery, and the diagnosis was confirmed by histological examinations. LC-OCT and RCM criteria for AK/SCC were identified, and their presence/absence was evaluated in all study lesions. Gwet AC1 concordance index was calculated to compare RCM and LC-OCT. Results: We included 52 patients with 33 AKs and 19 SCCs. Irregular epidermis was visible in most tumours and with a good degree of agreement between RCM and ...

Line-field confocal optical coherence tomography (LC-OCT) as a new tool for non-invasive differential diagnosis of pustular skin disorders

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Background: The spectrum of pustular skin disorders (PSD) is large and particularly challenging, including inflammatory, infectious and amicrobial diseases. Moreover, although pustules represent the unifying clinical feature, they can be absent or not fully developed in the early stage of the disease. The line-field confocal optical coherence tomography (LC-OCT) is a recently developed imaging technique able to perform a non-invasive, in vivo, examination of the epidermis and upper dermis, reaching very high image resolution and virtual histology. Objectives: We aimed to investigate the potentialities of LC-OCT in the non-invasive differential diagnosis of a series of 11 PSD with different etiology, microscopic features, body location and incidence rates. Materials and methods: Complete LC-OCT imaging (i.e., 2D/3D frames, videos) was performed on a total of 19 patients (10 females and 9 males) aged between 35 and 79 years. Images were blindly evaluated and compared with correspondin...

Co-localized line-field confocal optical coherence tomography and confocal Raman microspectroscopy for three-dimensional high-resolution morphological and molecular characterization of skin tissues ex vivo

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Line-field confocal optical coherence tomography (LC-OCT) is an optical modality that provides three-dimensional (3D) images of the skin at cellular resolution. Confocal Raman microspectroscopy (CRM) is a label-free optical technique that can provide point measurement of the molecular content of the skin. This work presents a method to co-localize LC-OCT and CRM acquisitions for morpho-molecular analysis of ex vivo skin tissues at cellular level. The co-localization method allows acquisition of Raman spectra at specific locations in a sample identified from a 3D LC-OCT image, with an accuracy of ± 20 µm. The method was applied to the characterization of tattooed skin biopsies with adverse tattoo reactions. LC-OCT images allowed to target specific regions in the biopsies where the presence of tattoo ink was revealed by detection of the Raman signature of ink pigments. Micrometer-sized foreign bodies of various materials as well as inflammatory cells were also identified ...

Non-invasive scoring of cellular atypia in keratinocyte cancers in 3D LC-OCT images using Deep Learning

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Diagnosis based on histopathology for skin cancer detection is today's gold standard and relies on the presence or absence of biomarkers and cellular atypia. However it suffers drawbacks: it requires a strong expertise and is time-consuming. Moreover the notion of atypia or dysplasia of the visible cells used for diagnosis is very subjective, with poor inter-rater agreement reported in the literature. Lastly, histology requires a biopsy which is an invasive procedure and only captures a small sample of the lesion, which is insufficient in the context of large fields of cancerization. Here we demonstrate that the notion of cellular atypia can be objectively defined and quantified with a non-invasive in-vivo approach in three dimensions (3D). A Deep Learning (DL) algorithm is trained to segment keratinocyte (KC) nuclei from Line-field Confocal Optical Coherence Tomography (LC-OCT) 3D images. Based on these segmentations, a series of quantitative, reproducible and biologically relevant...

Line-field confocal optical coherence tomography of actinic keratosis: a case series

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Line-field confocal optical coherence tomography (LC-OCT) is a non-invasive imaging technique that was recently developed, combining high penetration depth (up to 500-µm, approaching that of conventional OCT) with high isotropic resolution [lateral: 1.3 µm; axial: 1.1 µm - similar to that of reflectance confocal microscopy (RCM)]. 1 . ( Read Full Article )

Line-field confocal optical coherence tomography of sebaceous hyperplasia: a case series

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Line-field confocal optical coherence tomography (LC-OCT) is a newly developed non-invasive imaging technique that combines high penetration depth (500 µm, similar to conventional OCT) with high isotropic resolution (lateral 1.3 µm, axial 1.1 µm, similar to reflectance confocal microscopy [RCM]). 1 Moreover, with its ability to produce images in both vertical and horizontal planes, it enables a tridimensional (3D) analysis of the skin, which can prove very useful for assessing physiological 2 as well as pathological skin. ( Read Full Article )

Line-field confocal optical coherence tomography for three-dimensional skin imaging

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This paper reports on the latest advances in line-field confocal optical coherence tomography (LC-OCT), a recently invented imaging technology that now allows the generation of either horizontal ( x × y ) section images at an adjustable depth or vertical ( x × z ) section images at an adjustable lateral position, as well as three-dimensional images. For both two-dimensional imaging modes, images are acquired in real-time, with real-time control of the depth and lateral positions. Three-dimensional ( x × y × z ) images are acquired from a stack of horizontal section images. The device is in the form of a portable probe. The handle of the probe has a button and a scroll wheel allowing the user to control the imaging modes. Using a supercontinuum laser as a broadband light source and a high numerical microscope objective, an isotropic spatial resolution of ∼1 µm is achieved. The field of view of the three-dimensional images is 1.2 mm × 0.5 mm &ti...

Delayed Tattoo Reaction From Red Dye With Overlapping Clinicopathological Features: Examination With High-Frequency Ultrasound and Line-Field Optical Coherence Tomography

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Introduction Delayed tattoo reactions include a wide range of clinical presentations and overlapping forms; thus diagnosis can be challenging. We present a case of a delayed tattoo reaction from red dye. Case Presentation An otherwise healthy 40-year-old man presented with firm elevated plaques that arose 4 months previously, within a multicolored tattoo on the right forearm, 8 months after the execution of the tattoo ( Figure 1A ). The patient claimed minimal and only occasional itching. Polarized dermoscopy (Luminis Visiomed, Caliber) highlighted multiple keratotic plugs within the lesion, limited to the red-dyed areas ( Figure 1 ). Examination with line-field confocal optical coherence tomography (LC-OCT) [ 1 ] of both the transitional lesional-to-healthy part ( Figure 1C ) and the central part of the lesion ( Figure 2A ) showed a hyperkeratotic flattened epidermis and a blurred basal membrane due to the presence of inflammatory infiltrate, suggesting a lichenoid/interface dermat...

Line-field confocal optical coherence tomography for high-resolution noninvasive imaging of skin tumors

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An optical technique called line-field confocal optical coherence tomography (LC-OCT) is introduced for high-resolution, noninvasive imaging of human skin in vivo . LC-OCT combines the principles of time-domain optical coherence tomography and confocal microscopy with line illumination and detection using a broadband laser and a line-scan camera. LC-OCT measures the echo-time delay and amplitude of light backscattered from cutaneous microstructures through low-coherence interferometry associated with confocal spatial filtering. Multiple A-scans are acquired simultaneously while dynamically adjusting the focus. The resulting cross-sectional B-scan image is produced in real time at 10  frame  /  s. With an isotropic spatial resolution of ∼1  μm, the LC-OCT images reveal a comprehensive structural mapping of skin at the cellular level down to a depth of ∼500  μm. LC-OCT has been applied to the imaging o...

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