Advancing noninvasive diagnostics with 3D high-frequency ultrasound for early detection of inflammatory changes in cicatricial alopecia

Summary: Abstract Body: Three-dimensional high-frequency ultrasound (3D-HFUS) is an emerging technology that enables microstructural skin visualization, including hair follicles (HFs). We developed a novel 3D-HFUS device equipped with an automated transducer and attempted to assess its utility in diagnosing cicatricial alopecia (CA). Thirteen CA patients, including 4 lichen planopilaris (LPP), 3 fibrosing alopecia in a pattern distribution (FAPD), 2 folliculitis decalvans (FD), 2 frontal fibrosing alopecia (FFA) and 2 chronic cutaneous lupus erythematosus (CCLE) were involved along with one healthy control. Ultrasonographic data were analyzed in comparison with trichoscopic and/or histopathological findings. Contrary to healthy control, 50% of CA patients (3 LPP, 2 FD, 1 FFA) demonstrated a smaller number of follicular openings than that of follicular units (FUs), reflecting the distal disappearance of HFs. Notably, some FUs manifested a linear hypoechoic tract, namely a “tadpole” sign, at the isthmus level of transverse images. This sign was observed in 3 LPP, 2 FAPD, 1 FFA and 2 CCLE patients. Patients with perifollicular scales or erythema tend to present more tadpole signs, while the sign was absent in those with tufted hairs. Tadpole signs tended to be associated with perifollicular inflammation. Interestingly, the percentage of hair follicles with the sign showed a negative correlation with that of hair follicles accompanying perifollicular fibrosis (r = -0.483), suggesting that the sign may reflect early inflammatory changes preceding full-blown fibrosis and hair tufting. Additional analyses are indispensable to draw a definitive conclusion; the outcome suggested the usefulness of 3D-HFUS in CA diagnosis and highlighted the possibility of noninvasively detecting incipient and clinically indistinguishable pathological changes, which potentially facilitates therapeutic intervention before HFs are irreversibly damaged. Tatsuro Iwasaki^{1, 2}, Misaki Kinoshita-Ise¹, Taiichiro Ida³, Masayuki Amagai², Manabu Ohyama¹ 1. Dermatology, Kyorin University Faculty of Medicine, Mitaka-shi, Japan. 2. Dermatology, Keio University School of Medicine, Shinjuku-ku, Japan. 3. Advantest Corporation, Kazo-shi, Japan. Bioinformatics, Computational Biology, and Imaging