Abstract: 【Abstract】 Objective To comprehensively evaluate the skin thickness, blood flow grades, skin stiffness, and post-treatment changes in ultrasound indices in patients with different clinical types of port-wine stains （PWS） by multimodal ultrasound, and to explore the application value of multimodal ultrasound in the quantitative evaluation of and efficacy assessment for PWS. Methods An observational study was conducted, including 298 patients with PWS. High-frequency ultrasound was used to measure the thickness of and blood flow signals in skin lesions, and shear wave elastography to measure the maximum Young's modulus （Emax） and maximum shear wave propagation velocity （Cmax） of the skin layers. Differences in various ultrasound indices were analyzed between skin lesions and surrounding normal skin. After photodynamic therapy, ultrasound re-evaluation was performed on 124 patients to analyze changes in ultrasound indices before and after treatment. Statistical analysis was conducted using t test, analysis of variance, and rank sum test. Results In 106 patients with pink PWS, the skin thickness was 1.41 ± 0.28 mm, the blood flow was mainly rated as grade 0 （81%）, the Emax was 16.24 ± 1.82 kPa, and the Cmax was 2.28 ± 0.09 m/s. There were no significant differences in the above indices between normal skin and treated skin （all P > 0.05）. In the 121 patients with purplish red PWS, the skin thickness was 1.86 ± 0.23 mm; the blood flow was mainly rated as grade 1 （45%）, which was higher than that of normal skin; after treatment, both the skin thickness and blood flow grades were decreased （P < 0.05）; there were no significant differences in the Emax and Cmax between purplish red PWS lesions （16.41 ± 1.82 kPa, 2.32 ± 0.13 m/s, respectively） and normal skin or treated skin （all P > 0.05）. In the 71 patients with thickened PWS, the skin thickness was 2.51 ± 0.32 mm, the blood flow was mainly trated as grade 3 （55%）, the Emax was 22.22 ± 2.46 kPa, and the Cmax was 2.75 ± 0.11 m/s, which were all significantly higher than those of normal skin （all P < 0.05）; all the indices were decreased after treatment. Conclusions Multimodal ultrasound can be used for the quantitative assessment of different clinical types of PWS and their treatment outcomes. Purplish red PWS and thickened PWS showed thicker skin layers and higher blood flow grades, and thickened PWS showed higher skin stiffness values. All ultrasound indices were decreased after treatment.

Key words: Port-wine stain, Ultrasonography, Doppler, Elasticity imaging techniques, Photochemotherapy, Multimodal ultrasound, Shear wave elastography