Sonographic elastography for evaluation of masseter muscle hardness

Objectives The aims were to investigate the relationship between the masseter muscle elasticity index (MEI) ratio obtained by sonographic elastography and the hardness measured by a hardness meter in healthy volunteers, and to clarify the characteristics of the masseter muscle hardness in temporomandibular disorder (TMD) patients with myofascial pain. Methods Sonographic elastography images were obtained using a LOGIQ E9 (GE Healthcare), and the MEI ratios were calculated using Elasto Q software. The relationship between the MEI ratio and the masseter muscle hardness measured using a hardness meter was examined in 35 healthy volunteers. The MEI ratio in 8 TMD patients with myofascial pain was compared with that of the healthy volunteers. Results The MEI ratio was significantly correlated with the masseter muscle hardness. There was a significant difference between the MEI ratios of the symptomatic and asymptomatic sides in the TMD patients with myofascial pain. The MEI ratio of the symptomatic side in the TMD patients was larger than that on the right side of the healthy volunteers. Conclusion Sonographic elastography can be used to express the muscle hardness. It can be selected as a modality for showing the features of muscles with pain.