Assessment of Subepidermal Low‐Echogenic Band via High‐Frequency Ultrasound for Evaluating the Efficacy of Platelet‐Rich Plasma Injection in Treating Facial Skin Photoaging: A Case Series

ABSTRACT Background Facial skin photoaging manifests as wrinkles, laxity, roughness, enlarged pores, telangiectasia, pigmentation, and dermal structural changes. Histologically, dermal collagen degradation and dermal‐epidermal junction disruption form the subepidermal low‐echogenic band (SLEB) on ultrasound. Platelet‐rich plasma (PRP) injection promotes skin regeneration but lacks objective imaging biomarkers. Objective To objectively evaluate the structural efficacy of PRP for facial photoaging by quantifying SLEB width and dermal thickness changes via high‐frequency ultrasound (HFUS), alongside skin analyzer assessments. Methods This retrospective case series included 10 patients (Glogau I–III) receiving three monthly PRP injections. The treatment utilized a standardized dual‐step protocol: manual precision injection targeting the deep dermis, followed by mechanical mesogun injection for uniform superficial coverage. SLEB width and dermal thickness were measured at four facial sites using HFUS before and 1 month after treatment. A skin analyzer assessed skin parameters. A comprehensive clinical evaluation was conducted using the Glogau classification and Global Aesthetic Improvement Scale (GAIS) for efficacy and patient satisfaction assessment. Results Post‐treatment, HFUS revealed significant reductions in SLEB width (average decrease 29%–47%, all p < 0.001) and increases in dermal thickness (average increase 24%–51%, all p ≤ 0.003). Skin analyzer showed significant improvements in Pores, Wrinkles, Brown Spots, and Red Areas (all p < 0.05). Clinical evaluations confirmed significant improvement in Glogau classification ( p < 0.01) and high patient satisfaction (100% reported improvement on GAIS). No serious adverse events were observed; only transient erythema/edema and mild pain were reported. Conclusion HFUS is a reliable, non‐invasive tool for assessing PRP efficacy. SLEB width reduction serves as a sensitive, objective imaging biomarker, providing structural evidence for PRP's ability to improve photoaging damage.