U-SMAS: ultrasound findings of the superficial musculoaponeurotic system

The superficial musculoaponeurotic system (SMAS) is a complex fibrous network connecting facial muscles to the dermis, with varying morphological characteristics across different facial regions. Recent studies have identified five distinct types of SMAS morphology, highlighting the need for region-specific interventions in facial rejuvenation. This pictorial essay explores ultrasound imaging of the SMAS using ultra-high frequency (24-33 MHz) probes, known as U-SMAS. Analysis of 186 full-face U-SMAS scans revealed consistent patterns in the facial and neck layers, with regional variations aligning with the Sandulescu classifications: type I (preparotideal); type II (chin and lip); type III (eyelid); type IV (temporal and parotideal); and type V (cervical). Understanding these morphological differences is crucial for accurate interpretation of ultrasound images and for optimizing pre-procedural assessments to ensure that aesthetic treatments are safe and effective. Knowledge of the SMAS architecture enhances the ability to visualize facial and neck anatomy accurately, particularly through U-SMAS imaging, ensuring comprehensive patient care in rejuvenation procedures.