Regional assessments of supraspinatus muscle stiffness in normal adults using shear wave elastography.

Objectives: To provide normal references for regional shear wave elastography assessments of supraspinatus muscle in a population. Methods: Shear wave elastography images of supraspinatus muscles were evaluated on 100 shoulders of 50 normal adults in a fixed position with 30° shoulder abduction both at rest and contraction. Shear wave velocity values and activity values of intramuscular tendon, anterior superficial, anterior deep, posterior superficial, posterior deep, and central subregions were measured. The possible differences in hand dominance, sexes, stratified age groups, and internal muscular-component subregions were discussed. Results: The results showed that shear wave velocity values at rest and activity values differed significantly among supraspinatus muscular-component subregions. Shear wave velocity values at rest were normally highest in posterior deep and lowest in central subregions, whereas activity values were highest in central subregions. The results also showed evaluation of the intramuscular tendon using shear wave elastography to be practicable. The differences in shear wave velocity values at rest between the dominant and nondominant sides were not significant in each subregion, while the values at rest of the majority of subregions were significantly greater in males than in females. Stratified by age groups of 10 years, the shear wave velocity values at rest of some subregions tended to increase with age, with uncorrelations possibly related to insufficient sample sizes and different intensities of limb activities. Conclusions: This study suggested that regional assessments of supraspinatus stiffness using shear wave elastography are feasible, with further research supporting that it can provide information on the surgery, training, and rehabilitation of rotator cuff tears.