In vivo 3D photoacoustic and ultrasound analysis of hypopigmented skin lesions: A pilot study

Vitiligo needs early identification for proper intervention. Current adjunct diagnostic methods rely mostly on subjective visual inspection. Thus, identification of early or atypical vitiligo lesions among other hypopigmentation disorders may pose challenges. To overcome this, we investigate the feasibility of a three-dimensional (3D) photoacoustic (PA) and ultrasound (US) imaging technique as a new adjuvant analytic tool providing quantitative characterization of hypopigmentation features. This cross-sectional study was conducted at Seoul St. Mary's Hospital (Seoul, Republic of Korea) between August 2022 and January 2024. Lesions diagnosed vitiligo or IGH in locations that could safely be irradiated with laser were analyzed with 3D PA/US imaging along with the conventional diagnostic methods. A total of 53 lesions consisted of 36 vitiligo lesions and 17 IGH lesions from 39 participants with confirmed diagnosis were analyzed. The PA amplitude greatly differed between normal skin and hypopigmentation lesions, and the mean PA amplitudes of vitiligo lesions were slightly higher than that of IGH [mean (standard deviation, SD): vitiligo: 0.117 (0.043); IGH: 0.135 (0.028)]. The local SD of the PA amplitude were higher in IGH than in vitiligo lesions [vitiligo: 0.043 (0.018); IGH: 0.067 (0.017)]. The mean PA slope across the lesion boundary was significantly higher in IGH than in vitiligo [vitiligo: 0.173 (0.061); IGH: 0.342 (0.099)], whereas the PA peak depth was deeper in vitiligo than in IGH [vitiligo: 0.568 (0.262); IGH: 0.266 (0.116)]. Unlike conventional qualitative methods, 3D PA/US imaging can non-invasively provide quantitative metrics which might aid in the differentiation of vitiligo from IGH lesions.