Quantitative assessment of muscular stiffness in children with cerebral palsy using acoustic radiation force impulse (ARFI) ultrasound elastography

To evaluate the feasibility of quantitative analysis of muscle stiffness in the medial gastrocnemius muscle (GCM) by acoustic radiation force impulse (ARFI) ultrasound elastography in children with spastic cerebral palsy (CP). Seventeen children with spastic CP and 25 healthy children participated in the study between the years 2016-2017. The medial GCM in the CP group was assessed using the Modified Ashworth Scale (MAS) by a physiatrist. ARFI was used to measure the shear-wave velocities (SWVs) of the medial GCM. The mean SWV value for each MAS score was calculated and used for statistics. The mean SWV values of the medial GCM in the CP and healthy groups were 3.17 +/- 0.81 m/s (mean +/- SD) and 1.45 +/- 0.25 m/s (mean +/- SD), respectively. The SWV of the medial GCM significantly increased in the CP patients when compared with controls (p < 0.001). In addition, the SWV values were correlated with the MAS scores (p < 0.001). The interobserver agreement expressed as the interclass correlation coefficient was 0.65 (95% CI 0.33-0.84, p < 0.001). ARFI imaging demonstrated a difference in muscle stiffness in the medial GCM between the CP and healthy groups. This method is a feasible imaging modality for the noninvasive assessment of contracting muscles in children with CP.