Ultrasound Appearance of Superficial Versus Deep Facial Fat: The Role of Retinacula Cutis in Echogenicity

BACKGROUND: Superficial and deep facial fat are anatomically distinct, but their relative sonographic appearance in the perialar cheek has not been consistently described. OBJECTIVE: To evaluate the ultrasound appearance of superficial versus deep facial fat lateral to the alar base and to explore the relationship between echogenicity differences and the architecture of the retinacula cutis. METHODS: This cross-sectional observational study included 32 patients without prior aesthetic facial treatment. Ultrasound examination of the anterior cheek lateral to the alar base was performed with a ultrasoundsystem. Superficial and deep fat layers were identified on grayscale imaging using the dermis, the superficial fascial/SMAS region, mimetic muscle, and deeper planes as landmarks. Echogenicity was assessed qualitatively within the same scan. RESULTS: In 29 of 32 patients (90.6%), the superficial fat layer appeared more hyperechoic and more reticular than the deeper fat layer. The deep tissue was relatively more hypoechoic and homogeneous. In 3 patients, the contrast between the 2 layers was less distinct. CONCLUSION: In the anterior cheek, lateral to the alar base, superficial fat most often appears more hyperechoic than deeper fat on ultrasound. This difference is plausibly related to the denser network of retinacula cutis and fibrous septa in the superficial layer, which creates more acoustic interfaces and greater backscatter.