The Advanced Applications For Optical Coherence Tomography In Skin Imaging

Optical coherence tomography (OCT), based on the principle of interferometry, is a fast and non-invasive imaging modality, which has been approved by FDA for dermatologic applications. OCT has high spatial resolution up to micrometer scale compared to traditional ultrasound imaging. In addition, OCT can provide real-time cross-sectional images with 1 to 2 mm penetration depth, which makes it an ideal imaging technique to assess the skin micro-morphology and pathology without any tissue removal. Many studies have investigated the possibilities of using OCT to evaluate dermatologic conditions, such as skin cancer, dermatitis, psoriasis, and skin damages. Hence, OCT has tremendous potential to provide skin histological and pathological information and assist differential diagnosis of various skin diseases. In this study, we used a swept-source OCT with 1305 nm central wavelength to explore its advanced applications in dermatology. This dissertation consists of four major research projects. First, we explored the feasibility of OCT imaging for assisting real-time visualization in skin biopsy. We showed that OCT could be used to guide and track a needle insertion in mouse skin in real-time. The structure of skin and the movement of needle can be clearly seen on the OCT images without any time delay during the procedures. Next, we tested the concept of performing the punch biopsy using OCT hand-held probe attached to a piercing tip in a phantom. We proved that using the OCT is a reliable technique to delineate the margin of lesion in phantom. And it is possible to perform the punch biopsy with the OCT probe. Second, we tested the performance of contrast-enhanced OCT in melanoma detection in an in vitro study. Melanoma is the most lethal type of skin cancer. Early detection could significantly improve the long-term survival rate of patients. In this initial study, a contrast agent (Gal3-USGNPs) is developed by conjugating melanoma biomarker (Gal3) to ultra-small gold nanoparticles (USGNPs). We showed that the contrast agent can differentiate B16 melanoma cells from normal skin keratinocytes in vitro. To avoid systemic administration of USGNPs, the third project continues to explore the enhanced topical delivery of USGNPs. In this study, we used OCT to monitor the topical delivery of nanoparticles on pig skin over time. And the diffusion and penetration of USGNPs in skin can be improved by applying chemical and physical enhancers such as DMSO and sonophoresis. Finally, in addition to image the cross-sectional structure of skin, we also aim to extract quantitative information from OCT images. The skin optical properties such as attenuation coefficient can be measured from OCT images. We measured and compared the skin attenuation coefficient in the skin of forehead and lateral hip, the skin of three different age groups, and the skin of three different Fitzpatrick types. The statistical analysis showed that epidermis has much higher attenuation coefficient than dermis. And the skin type V & VI have a relatively lower attenuation coefficient than the other skin types. These studies could aid the detection of skin cancer using imaging techniques and provide some new insights into the future applications of OCT in dermatology

Objective localisation of oral mucosal lesions using optical coherence tomography.

PhDIdentification of the most representative location for biopsy is critical in establishing the definitive diagnosis of oral mucosal lesions. Currently, this process involves visual evaluation of the colour characteristics of tissue aided by topical application of contrast enhancing agents. Although, this approach is widely practiced, it remains limited by its lack of objectivity in identifying and delineating suspicious areas for biopsy. To overcome this drawback there is a need to introduce a technique that would provide macroscopic guidance based on microscopic imaging and analysis. Optical Coherence Tomography is an emerging high resolution biomedical imaging modality that can potentially be used as an in vivo tool for selection of the most appropriate site for biopsy. This thesis investigates the use of OCT for qualitative and quantitative mapping of oral mucosal lesions. Feasibility studies were performed on patient biopsy samples prior to histopathological processing using a commercial OCT microscope. Qualitative imaging results examining a variety of normal, benign, inflammatory and premalignant lesions of the oral mucosa will be presented. Furthermore, the identification and utilisation of a common quantifiable parameter in OCT and histology of images of normal and dysplastic oral epithelium will be explored thus ensuring objective and reproducible mapping of the progression of oral carcinogenesis. Finally, the selection of the most representative biopsy site of oral epithelial dysplasia would be investigated using a novel approach, scattering attenuation microscopy. It is hoped this approach may help convey more clinical meaning than the conventional visualisation of OCT images

Biomedical Photoacoustic Imaging and Sensing Using Affordable Resources

The overarching goal of this book is to provide a current picture of the latest developments in the capabilities of biomedical photoacoustic imaging and sensing in an affordable setting, such as advances in the technology involving light sources, and delivery, acoustic detection, and image reconstruction and processing algorithms. This book includes 14 chapters from globally prominent researchers , covering a comprehensive spectrum of photoacoustic imaging topics from technology developments and novel imaging methods to preclinical and clinical studies, predominantly in a cost-effective setting. Affordability is undoubtedly an important factor to be considered in the following years to help translate photoacoustic imaging to clinics around the globe. This first-ever book focused on biomedical photoacoustic imaging and sensing using affordable resources is thus timely, especially considering the fact that this technique is facing an exciting transition from benchtop to bedside. Given its scope, the book will appeal to scientists and engineers in academia and industry, as well as medical experts interested in the clinical applications of photoacoustic imaging

Μελέτη της χρήσης της τεχνητής νοημοσύνης (artificial intelligence) στην έγκαιρη διάγνωση του καρκίνου δέρματος

Η Τεχνητή Νοημοσύνη έχει ενσωματωθεί σε πολλές πτυχές της καθημερινότητας μας και η Ιατρική δεν θα μπορούσε να αποτελέσει εξαίρεση. Πλειάδα επιστημονικών άρθρων έχουν εξερευνήσει την εφαρμογή της Τεχνητής Νοημοσύνης σε τομείς όπως η Οφθαλμολογία και η Ακτινολογία, ενώ υπάρχουν ήδη εγκεκριμένες εφαρμογές Τεχνητής Νοημοσύνης οι οποίες χρησιμοποιούνται στην καθημερινή κλινική πράξη. Κατά τη διάρκεια της διδακτορικής μας διατριβής επιχειρήσαμε να διερευνήσουμε (1) Το κατά πόσον μπορεί η Τεχνητή Νοημοσύνη να χρησιμοποιηθεί στην έγκαιρη διάγνωση του καρκίνου δέρματος; (2) Ποια είναι τα μειονεκτήματα των εφαρμογών της Τεχνητής Νοημοσύνης στη δερματολογία μέχρι στιγμής και πως μπορούν να βελτιωθούν; (3) Που θα μπορούσε δυνητικά να βρει εφαρμογή η Τεχνητή Νοημοσύνη στη δερματολογία και με ποιο τρόπο θα ήταν χρήσιμη; (4) Ποια είναι η βέλτιστη προσέγγιση και ερμηνεία των αποτελεσμάτων που παράγονται τόσο από την έρευνα, όσο και από την εφαρμογή της Τεχνητής Νοημοσύνης στη δερματολογία; Και (5) Πως μπορούμε να βελτιώσουμε τη διαγνωστική ακρίβεια τόσο των κλινικών ιατρών, όσο και των αλγορίθμων Τεχνητής Νοημοσύνης για την έγκαιρη διάγνωση του καρκίνου δέρματος και ειδικότερα του μελανώματος; Τέλος, επιχειρήσαμε να περιγράψουμε το πλαίσιο, εντός του οποίου, οι αλγόριθμοι Τεχνητής Νοημοσύνης θα μπορούσαν να φανούν χρήσιμοι στην κλινική πράξη, προς όφελος των ασθενών.Artificial Intelligence (AI) has been incorporated in a wide spectrum of our daily lives, and Medicine could be no exemption to it. A plurality of scientific articles has explored the application of AI in fields such as Ophthalmology and Radiology, while there are already FDA approved, AI applications, which are used in clinical practice. Through our research we explored: (1) Can AI be used in early skin cancer diagnosis? (2) Which are the pitfalls of AI algorithms in Dermatology and in which possible ways could they be improved upon? (3) How could AI be of use in Dermatology, and in which ways could it be used? (4) Which is the best approach to the research conducted with regards to AI algorithms in early skin cancer diagnosis, and how should these results be interpreted? And (5), how can we improve the diagnostic accuracy of clinicians and AI algorithms for early skin cancer diagnosis and more specifically, melanoma? Finally, we attempted to describe the overall framework, within which, AI algorithms could be proven useful in clinical practice, and more importantly, beneficial to the patients