Longitudinal Multimodal Imaging Assessment of Tissue Changes Following Poly‐L‐Lactic Acid Treatment for Midfacial Rejuvenation: An Exploratory Pilot Study

ABSTRACT Background Poly‐L‐lactic acid (PLLA) is increasingly used as a collagen‐stimulating injectable for facial rejuvenation, but longitudinal multimodal characterization of volumetric and tissue remodeling changes after treatment remains limited. Aims To characterize longitudinal changes in midfacial volume, ultrasound‐derived dermal remodeling parameters, and skin hydration after individualized PLLA treatment, and to explore the potential associations between administered PLLA amount and observed volumetric changes. Methods Six adults with mild‐to‐moderate midfacial volume deficiency were enrolled in this prospective exploratory pilot study. Twelve hemifaces were treated with individualized PLLA injections over up to three sessions. Outcomes were assessed at baseline and Days 30, 90, 180, and 360 using 3D stereophotogrammetry, high‐frequency ultrasound, Corneometer measurements, standardized photography, and safety evaluation. Results Exploratory analysis suggested a positive association between administered PLLA amount and observed volumetric changes at certain follow‐up time points, with the strongest association observed at Day 90. Mean volumetric increase was greatest at Day 360, whereas ultrasound‐derived dermal remodeling parameters and skin hydration peaked at Day 90 and remained elevated relative to baseline through Day 360. No serious treatment‐related adverse events were observed. Conclusions In this exploratory cohort, individualized PLLA treatment was associated with longitudinal changes in midfacial volume and sustained alterations in ultrasound‐derived parameters related to dermal remodeling over 12 months. The observed association between administered PLLA amount and volumetric changes warrants further investigation in controlled studies to better understand factors contributing to variability in treatment outcomes.