(L-463) Optical Coherence Tomography Angiography for the diagnosis of Vulvar Lichen Sclerosus

Introduction:: Lichen sclerosus (LS) is a chronic inflammatory skin condition that has a predilection for the anogenital skin in women. The true prevalence of vulvar LS is unknown, underdiagnosed, and underreported. Studies have estimated LS affects up to 3% of postmenopausal women, with a rising incidence. The disease also affects premenopausal women and children. Overall, this is an underserved condition and the related delay in diagnosis can have a profound burden on patients’ quality of life and health outcomes, leading to irreversible scarring, infection, vulvar architectural distortion, genitourinary complications, itch, and pain syndromes. There is a limited understanding of disease pathogenesis and no FDA-approved treatment options, with current guidelines recommending lifelong treatment. Vulvar LS is challenging to diagnose as skin findings may be subtle at the time of initial presentation and the accuracy of diagnosis often depends on the skills and experience of examiners. To obtain an accurate diagnosis, skin biopsies are the gold standard for the detection of LS. However, there are disadvantages to vulvar biopsies, as they are invasive, particularly in the sensitive vulvar region, and are time-consuming. Up to 5% of women with LS develop vulvar squamous cell carcinoma (SCC) with half of all vulvar cancers arising in the setting of LS. Thus, patients must be monitored frequently, and additional biopsies are often required to evaluate for the development of SCC or its precursors in longstanding lesions of LS. In this study, we develop a 1.7-micron OCT Angiography for the non-invasive diagnosis of vulvar LS.


Materials and Methods:: System setup:

The system consists of a Mach-Zehnder interferometer (MZI) with a 1.7 µm center wavelength-swept light source. The output energy is split by a 90:10 coupler. 90% of the energy is supplied to the sample arm and the remaining 10% is supplied to the reference arm. The system is equipped with a Fiber Bragg Grating (FBG) for increased phase stability. The reference arm consists of a collimator, lens, and mirror. The sample arm supplied with 90% energy consists of a hand-held probe with a threaded adapter to adjust the focal length. The handheld probe is equipped with a dual-axis galvanometer and a scan lens for 3D OCT imaging. Two circulators with a center wavelength of 1650 nm are used to separate the illumination light and back-reflected light. The interference signal generated by the sample and reference arm in the 50:50 coupler is detected by the photodetector. The data acquisition software is written in C++ which allows for faster data processing.

Human experiment:

Experiments were carried out in accordance with the protocol approved by the Institutional Review Board at the University of California, Irvine. 6 vulvar LS patients were recruited from the Department of Dermatology, University of California, Irvine. The OCTA imaging was performed in the presence of a clinician. The imaging session took approximately 30 seconds to complete. The handheld probe was sterilized after application on each subject. The imaging area of subjects included the labia majora and labia minora area as well as the adjacent healthy tissue.


Results, Conclusions, and Discussions:: Results:

The 6×6 mm OCTA images reveal the vasculature of the vulvar LS, as well as the supporting vessels compared to healthy subjects. The OCTA images of 6 subjects are analyzed and the vascular density and diameter are quantified. OCTA elucidates the vascular changes on the vulvar skin surface. The quantitative assessment provides an in-depth idea of the vascular density and diameter of the lesions and adjacent vessels on the surface of the skin. OCTA images of skin lesions from a 1.7 μm center-wavelength light source system acquired are highly effective in visualizing the morphology and improving the penetration depth by 25% compared to the conventional 1.3 μm OCT systems. Hence, this system will be helpful to obtain simultaneous information on structural and functional changes in vulvar lesions.



Conclusion and Discussion:

In this study, we demonstrated that OCTA, as a functional extension of OCT can be used to non-invasively scan vulvar lesions in vivo. We scanned 6 subjects with lesions in different areas including labia majora and labia minora. We were able to quantify the vascular density and diameter of lesions and adjacent healthy tissue. Research on vulvar diseases remains in the very early stages.
OCT angiography (OCTA), as a functional augmentation of OCT, allows for the visualization of cutaneous microvasculature via the detection of fluctuations in amplitude and/or phase of sequential OCT signal with high resolution and sensitivity. This instrument will help in therapeutic monitoring, and earlier detection of malignant transformation, in vulvovaginal conditions.




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