Applications and Future Directions for Optical Coherence Tomography in Dermatology

B. Wan; C. Ganier; X. Du-Harpur; N. Harun; F.M. Watt; R. Patalay; M.D. Lynch

Disclosures

The British Journal of Dermatology. 2021;184(6):1014-1022. 

In This Article

Discussion

OCT is an in vivo imaging modality within dermatology. It fills a gap between the cellular resolution achievable by RCM and the lower resolution of ultrasound. The technology is of interest to dermatologists as it offers the potential for rapid, noninvasive diagnosis for skin cancer and disease monitoring in inflammatory dermatoses.

To date, OCT has been most extensively investigated for the diagnosis of keratinocyte carcinomas, particularly BCC. A large number of studies have been performed, with considerable variability in reported values for sensitivity and specificity. A systematic review published in the British Journal of Dermatology found considerable variability between studies.[37] The explanations for this degree of variation are likely multifactorial, including differences in technology and the specifics of study design; however, it is likely that operator experience and skill play key roles.[92] With regard to the latter, it will be of great interest to explore a potential role for artificial intelligence approaches in automating and improving the accuracy of the diagnosis of BCC. Deep-learning algorithms have been applied to OCT in ophthalmology.[93,94] In dermatology, a study used nonparametric machine learning algorithms for skin cancer classification,[95] and machine learning has also been used to analyse polarization-sensitive OCT data.[32]

As for any new technology, it is important to explore health economic considerations. OCT machines are currently expensive and require a skilled clinician for interpretation of imaging data. The amortized cost of the machine in combination with the time taken for the clinician to perform scans will have to be weighed against cost savings resulting from a reduction in the need for biopsies and reduced patient visits. The time taken to train a clinician in the use of an OCT machine with a high degree of accuracy will also need to be incorporated in this calculation.

While OCT does not achieve accuracy of diagnosis comparable with that of conventional histopathology, an advantage is the possibility of rapid noninvasive diagnosis, reducing the requirements for skin biopsy and reducing patient anxiety waiting for results. This is potentially of great value as many healthcare systems have an intense resource pressure on the provision of skin cancer services. There is also the possibility that OCT could serve as an adjunct to teledermatology in primary care settings including general practice. Another clinical scenario where OCT may be of value is in screening patients at very high risk of skin cancer – due to either extensive ultraviolet exposure, immunosuppression or genetic conditions such as epidermolysis bullosa or xeroderma pigmentosum, where it is impractical to biopsy all indeterminate lesions. The noninvasive nature of OCT additionally facilitates serial imaging for the assessment of disease activity. This is desirable in monitoring the response to systemic therapy of inflammatory dermatoses such as psoriasis, and connective tissue diseases such as scleroderma. It can also potentially be of value in other conditions, including scarring alopecia.

While OCT has demonstrated accuracy in the diagnosis of keratinocyte carcinomas and has received Food and Drug Administration approval,[51] it has not achieved the same degree of clinical maturity – namely documented impact on routine patient outcomes – as visual inspection or dermoscopy. If it is to bridge this gap, rather than remaining a niche diagnostic tool employed predominantly in specialist centres, there will need to be more widespread adoption in combination with larger and more robust multicentre studies of diagnostic accuracy. This will likely require a decrease in the cost of the equipment, which is currently too expensive for most departments, in combination with a reduction in the degree of training required to achieve accurate diagnosis, which might be achieved through the assistance of artificial intelligence.

In summary, OCT is a promising technology for the noninvasive imaging of skin, while the technology and potential indications continue to evolve. It shows particular promise in the early diagnosis of keratinocyte carcinomas and for disease monitoring in inflammatory dermatoses.

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