Positional relationship of superior and inferior labial artery by ultrasonography image analysis for safe lip augmentation procedures.

The aim of this study was to use ultrasonography to determine the locations and distributions of the superior labial artery (SLA) and the inferior labial artery (ILA) relative to the vermilion border (VB). Sixty healthy Korean volunteers (35 males, 25 females; age, 21-36 years) were investigated using ultrasonography. The participants had not received any noninvasive treatment or surgical procedure in the facial regions during the previous 6 months. Based on the VB, the overall thicknesses of the upper and lower lips were 9.4 ± 0.4 mm (mean ± SD) and 10.9 ± 0.7 mm, respectively. In most cases, the labial arteries were located in the wet mucosal layer on both the upper (35-57%) and lower lips (28-55%), respectively. In the upper lip, the SLA was in the intramuscular layer in 20-45% of cases, making it the second most common type. At some of the measuring points, the SLA was observed more often in the intramuscular layer than in the wet mucosal layer. In the lower lip, the ILA was also located in the dry mucosa (5-27%). The dry-wet mucosal junction is unclear in the lip area, and the ILA was commonly observed at the dry-wet mucosal junction. The arterial depth was 5.3 ± 0.3 mm in the upper lip and 4.2 ± 0.4 mm in the lower lip. The SLA and ILA are evenly distributed over all parts of the oral mucosa. Injection procedures for lip augmentation should therefore use very superficial approaches. Clin. Anat. 33:158-164, 2020.