Sonographic findings in muscle strain injury: clinical and MR imaging correlation.

Both sonography and magnetic resonance imaging were performed in 57 patients with clinically suspected strain injury in lower extremity muscles. Sonography demonstrated normal findings in nine patients (16%), hyperechoic infiltration in 31 patients (54%), mass in nine patients (16%), and compound lesions of infiltration and mass in eight patients (14%). Clinically grade 2 lesions ranged from small infiltration to large compound lesions on both sonography and magnetic resonance imaging. Hyperechoic infiltration was not demonstrated on T1-weighted magnetic resonance images and with less than 50% cross-sectional muscle involvement. The mass and compound lesions were ascertained to be moderate or severe injury because the masses of the lesions had obvious hemorrhage or hematoma on magnetic resonance images.