Objective assessment of dermal fibrosis in cutaneous scarring: using optical coherence tomography, high frequency ultrasound and immuno‐histo‐morphometry of human skin

Background Non‐invasive quantitative assessment of dermal fibrosis remains a challenge. Optical coherence tomography (OCT) and high‐frequency ultrasound (HFUS) can accurately measure structural and physiological changes in skin. Objectives To perform quantitative analysis of cutaneous fibrosis. Methods 62 healthy volunteers underwent multiple sequential skin biopsies (day 0 and 1‐8 weekly thereafter) with OCT and HFUS measurements at each time‐point supported with immuno‐histo‐morphometry analysis. Results HFUS and OCT provided quantitative measurements of skin thickness, which increased from uninjured skin (1·18mm, 1·2mm respectively) to week 1 (1·28mm;p=0·01, 1·27mm;p=0·02) and compared favourably with H&E. Spearman's correlation showed good agreement between techniques (p<0·001). HFUS intensity, corresponded to dermal density, with reduction from uninjured skin (42%) to week 8 (29%) (p=0·02). OCT attenuation coefficient linked with collagen density and reduced at week 8 (1·43mm) (p<0·001). Herovici analysis showed that mature collagen was highest in uninjured skin (72%) compared to week 8 (42%) (p=0·04). Elastin was highest in uninjured skin (49·1%) and lowest at week 4 (23·0%, p=0·01), fibronectin was greatest at week 4 (0·72Au) and reduced at week 8 (0·56Au) and α‐SMA increased from uninjured skin (11·5%) to week 8 (67%) (p=0·003). Conclusions Time‐matched comparison images between H&E, OCT and HFUS demonstrated that epidermal/dermal structures were better distinguished by OCT. HFUS enabled deeper visualisation of the dermis including the subcutaneous tissue. Choice of device was relevant upon the depth of scar type, parameters to be measured and morphological detail required in order to provide better objective quantitative indices of the quality and extent of dermal fibrosis.