Some representative image features will be expected to be computed from the SCM ultrasonic images. These features include area, both max and min Feret's diameters, and brightness of echogenicity in the region of interest. The ultrasonic image of the affected side would be compared with that of the sound side from their corresponding texture features. The Pearson's correlation will be performed to analyze the relevance of quantitative side differences of texture features in ultrasonography and clinical manifestations including side differences of neck rotation, lateral flexion and habitual head position between lesion sides and sound sides. Linear regression will be also used to adjust the influence of the treatment effect.