Reliability and Minimal Detectable Change of Muscle Thickness and Echo Intensity Measurements in the Lower Extremities of Inpatients with Stroke

[Purpose] This study determined the reliability and minimal detectable change of lower extremity muscle thickness measurements and ultrasound echo intensities of inpatients with stroke. [Participants and Methods] Ten patients with acute stroke were included in the study. Muscle thickness and echo intensity were measured of both leg muscles to assess muscle mass and muscle quality using ultrasonography. In order to verify the reliability of muscle thickness and echo intensity measurements, the intraclass correlation coefficient (ICC), standard error of measurement, 95% limit of agreement, and the minimal detectable change of the 95% confidence interval (MDC95) were calculated. [Results] The ICC was more than 0.70 for both the muscle thickness measurements and echo intensities, demonstrating high reliability. The MDC95 for muscle thickness ranged from 0.18 to 0.32 cm on the unaffected side and 0.13 to 0.30 cm on the affected side. The MDC95 for echo intensity ranged from 6.83 to 11.81 a.u. on the unaffected side and 6.21 to 13.49 a.u. on the affected side. [Conclusion] Evaluation of skeletal muscle by ultrasound of inpatients with stroke was highly reliable. These findings should contribute to future evaluations of the effectiveness of rehabilitation interventions by clarifying the MDC.