Sonographic elastography for assessing changes in masseter muscle elasticity after low-level static contraction

Unilateral temporal myositis heralding polymyositis: ultrasonographic and elastographic findings. Case report.

“…The method has not been reportedly used, to our knowledge, in temporal myositis and it is still unclear whether it could make a difference between muscle inflammation and hypertrophy. However, as the hardness may increase in the presence of edema, as the muscle is covered with a thick fascia, an increase in intramuscular pressure accompanied by an increase in the water content may increase hardness [20]. In our patient, strain elastography revealed no alteration in elasticity in the right temporal muscle, and, more important, no stiffness increase in this region.…”

“…The method has been reproducibly used in masseter muscles, and a potential relationship may exist between elasticity and edematous change in the masseter muscle [20]. The elastographic evaluation of the propagation velocity of the shear waves using the acoustic radiation force impulse method (ARFI) masseter muscles allows quantitative measurements of normal and post-irradiation masseter elasticity [21].…”

Evaluation of the masseter muscle elasticity with the use of acoustic coupling agents as references in strain sonoelastography

“…The compression force cannot be standardized, and the strain values obtained are relative values. 6,10 To reduce these problems affecting the validity of strain values, subcutaneous fat 6,[8][9][10] or some materials 1,2,12 are used as references. An experimental study clarified that the location of the reference areas did not affect the strain ratio, which corresponded to the EI ratio in the present study when the objective area was surrounded by a homogeneous structure in which the reference ROIs were set.…”

“…6,[8][9][10][11] In a straintype sonoelastography, the tissue displacement is measured under the external freehand compression with a sonographic probe, and the muscle strain is expressed as the elasticity index (EI), which was originally developed to be used in conjunction with the device applied in the present study. The EI is defined as the strain values of the target area compared with the average strain value of the whole area of interest (for which it is assigned a value of 1).…”

“…In our previous studies, therefore, the EI of subcutaneous fat tissue was used as a reference. 6,9,10 The EI ratio of the masseter muscle was defined as the EI of the masseter muscle divided by that of the subcutaneous fat tissue. This method might be useful for the comparison of acquired values among examinations within a person, whereas it might not be suitable for comparing values between individuals or for obtaining the average value of a certain group because the strain values of subcutaneous fat would vary individually.…”