The human skin is comprised by two layers; epidermis and dermis, separated by the dermo-epidermal junction (DEJ). The relevance of depicting DEJ and measurement of the epidermal thickness (ET) is e.g. seen for superficial skin cancers where delineation of DEJ is of prime prognostic importance. Another example is diagnosis of psoriasis where a thickened epidermis and a ridged DEJ is a hallmark.
Histopathological examination of biopsied tissue is traditionally performed to trace DEJ and measure ET. An efficient and precise method to locate DEJ and measure ET is optical coherence tomography (OCT) which is an in vivo and non-invasive technique. Because of significant changes in the refractive index across the DEJ, it is generally easily resolvable with OCT. However at certain body locations, such as the cheek and in regions of glabrous skin, it is difficult to visualize DEJ since refractive index changes are small.
We study the significance of ultrahigh resolution OCT combined with a shadow compensation algorithm in locating the DEJ of the cheek and the palm of the hand of ten healthy volunteers. For the study we use a home-built ultrahigh resolution OCT system and a commercially available OCT system designed for dermatology diagnostic.
With this comparative study we conclude on the signal statistics of both dermis and epidermis for the two OCT systems and how the differences of these affect the delineation of DEJ. We finally conclude on the significance of ultrahigh resolution OCT in detecting DEJ and measuring ET.
We explore how histopathology parameters influence OCT imaging of basal cell carcinomas (BCC) and
address whether such parameters correlate with the quality of the recorded OCT images. Our results
indicate that inflammation impairs OCT imaging and that sun-damaged skin can sometimes provide more
clear-cut images of skin cancer lesions using OCT imaging when compared to skin cancer surrounded by
skin without sun-damage.
Introduction: Non-melanoma skin cancer (NMSC) is the most prevalent cancer in the Western World.
OCT has proved potential in assisting clinical diagnosis and perhaps reducing the need for biopsies in NMSC.
As non-invasive treatment is increasingly used for NMSC patients with superficial lesions, the development
of non-invasive diagnostic technologies is highly relevant.
Methods: The aim of this cross-sectional clinical study, enrolling 100 NMSC patients and 20 healthy
volunteers, is to investigate the diagnostic accuracy and applicability of OCT in NMSC diagnosis. Our OCT-system
has been developed at Risoe National Laboratory, Denmark and offers ppolarization sensitive-OCT
(PS-OCT) that may have additional advantaged as NMSC differ in content of birefringent collagens from
normal skin.
Results: Basal cell carcinomas (BCC) can in some cases be distinguished from normal skin in OCT-images,
as normal skin exhibits a layered structure this layering is not present in BCC and sometimes not in actinic
keratosis (AK). BCC lesions seem to be clearly less reflective than normal tissue. The predictive value of
OCT in NMSC will be presented from a clinical point of view.
Discussion: The earlier a skin cancer is diagnosed, the better the prognosis. Estimation of diagnostic
accuracy and abilities of OCT in clinical studies of skin cancer patients is essential to establish the role and
future set-ups for diagnostic OCT-systems.
A range of compounding techniques have been suggested for dealing with the signal degrading speckle noise in optical
coherence tomography (OCT). Recent implementations of angular compounding have shown great promise, but some of
the implementations require substantial modifications of the OCT system. Here, we consider a method that in principle
can be fitted to most OCT systems without major modifications. Specifically, we address a spatial diversity technique for
suppressing speckle noise in OCT images of human skin. The method is a variant of changing the position of the sample
relative to the measuring probe. Instead of physically moving the sample, which is often not feasible for in vivo imaging,
the position of the focal plane of the probe beam is shifted. If the numerical aperture is sufficiently high this spatial
diversity scheme incorporates a variant of angular compounding. We have tested the scheme with a mobile fiber-based
time-domain real-time OCT system. Essential enhancement was obtained in image contrast when performing in vivo
imaging of normal skin and lesions. Resulting images show improved delineation of structure in correspondence with the
observed improvements in contrast-to-noise ratios.
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