Methods of masseter and temporal muscle thickness and elasticity measurements by ultrasound imagining: a literature review.

Abstract

Background: The positive correlation between changes in morphology of masseter and temporal muscles, and some disorders, incline diagnosticians to search for an effective method of assessment muscle thickness and elasticity. Ultrasound imaging as a relatively simple and cheap method seems to be a useful diagnostic tool. Objective: The aim of this study was to present the existing ultrasound imaging methods in the assessment of the elasticity and thickness of the masseter and temporal muscles. Methods: The literature review has been done with a focus on the accurate description of the masseter and/or temporal muscle examination by ultrasonography imaging methods. Articles were categorized into two groups. First group included articles in which muscle thickness was assessed by ultrasound imaging. Second group concerned elasticity aspect of mentioned muscles. Results: It is difficult to achieve an objective protocol of masseter and temporal thickness assessment by ultrasonography and there is no method that has been fully verified in terms of reliability. The shear-wave sonoelastography revealed higher-level reliability of masseter muscle elasticity than strain sonoelastography. During the shear-wave sonoelastography the effect of scan plane in relation to masseter muscle pennation and the day-to-day variation were statistically significant. With regard to elasticity of temporal muscle further research is needed. Conclusion: This review has shown that there is a limited number of methods for masseter and temporal muscle thickness and elasticity measurements by ultrasonography. All procedures (methods) were not fully verified in terms of reliability and agreement. Thus, it is still necessary to develop standardize procures to assess thickness and elasticity of the masseter and temporal muscles with appropriate reliability and agreement.