Methodological and clinical aspects of ultrasound examination of maxillofacial skin and subcutaneous structures

Introduction of high-frequency ultrasound technologies has significantly expanded the diagnostic capabilities of ultrasound examination of maxillofacial skin and subcutaneous structures, and it has become possible to obtain highly detailed images of previously inaccessible elements of the echostructure. However, at present, the problem of results variability remains relevant, due to examination quality dependence on the specialist's professional qualifications and the choice of optimal scanning modes. The aim of the study was to evaluate the echostructure of the maxillofacial skin and soft tissues with conducting a comparative analysis of similar structures of the neck and scalp. Materials and methods. 20 healthy reproductive age women (average age – 31.6±0.37 years) were examined using Resona 7 ultrasound scanner (Mindray, China) with linear high-density sensors L9-3U and L11-3U. The modes of two-dimensional gray scale, color and power Doppler mapping were used with extended standard protocol for assessing vascularization using the V Flow scanner software, two-dimensional shear wave elastography with elastometry. Qualitative and quantitative assessment of elastic properties of the skin and soft tissues was performed after receiving correct measurements performed in at least three areas of interest, with automatic calculation of the values by the device and registration of the average, minimum and maximum stiffness values and the standard deviation coefficient. The diameter of measurements during the study in the mode of two–dimensional shear wave elastography with elastometry of all the above-mentioned regions in the skin assessment did not exceed 2 mm, that in soft tissues – 5 mm. The results of ultrasound evaluation of the echostructure of maxillofacial skin and soft tissues, the anterior surface of the neck region in the sublingual triangle region, the submandibular region, and the scalp in the symmetrical zones of the corresponding areas on the left and right were subjected to a comparative analysis. Results. The echogenicity of the epidermis in healthy reproductive age women was determined to be higher (hyperechoic) than the dermis, while the hypodermis had a moderately decreased echogenicity of a homogeneous structure, and soft muscle tissues were also hypoechoic, but with the presence of hyperechoic filamentous structures. The hypodermis was significantly thicker in the maxillofacial region than the epidermis and dermis. A lesser thickness of the hypodermis is determined in the neck region and scalp. A comparative morphometric analysis of the quantitative thickness values of skin echostructures and subcutaneous structures on the left and right, conducted in different zones, did not show statistically significant differences depending on the side of the study. In all areas of the study, the average quantitative values of epidermal stiffness were higher than those of the dermis and hypodermis. Conclusions. The use of an extended protocol using high-density linear sensors and modern ultrasound technologies (such as shear wave elastography) and advanced scanner features (such as image visualization and vascularization enhancement modes) make it possible to obtain additional diagnostic information in a non-invasive way in assessing the normal maxillofacial, neck and scalp structures.