Reliability and Validity of Muscle Size and Quality Analysis Techniques.

Objective: This study investigated reliability and validity of muscle cross-sectional area and echo intensity using an automatic image analysis program.

Methods: Twenty-two participants completed two data collection trials consisting of ultrasound imaging of the vastus lateralis (VL) at 10 and 12 MHz. Images were analyzed manually and with Deep Anatomical Cross-Sectional Area (DeepACSA). Reliability statistics (i.e., intraclass correlation coefficient [ICC] model 2,1, standard error of measure expressed as a percentage of the mean [SEM%], minimal differences [MD] values needed to be considered real) and validity statistics (i.e., constant error [CE], total error [TE], standard error of the estimate [SEE]) were calculated.

Results: Automatic analyses of ACSA and EI demonstrated good reliability (10 MHz: ICC = 0.83 - 0.90; 12 MHz: ICC = 0.87-0.88), while manual analyses demonstrated moderate to excellent reliability (10 MHz: ICC = 0.82-0.99; 12 MHz: ICC = 0.73-0.99). Automatic analyses of ACSA presented greater error at 10 (CE = -0.76 cm, TE = 4.94 cm, SEE = 3.65 cm) than 12 MHz (CE = 0.17 cm, TE = 3.44 cm, SEE = 3.11 cm). Analyses of EI presented greater error at 10 (CE = 3.35 a.u., TE = 2.70 a.u., SEE = 2.58 a.u.) than at 12 MHz (CE = 3.21 a.u., TE = 2.61 a.u., SEE = 2.34 a.u.).

Conclusion: The results suggest the DeepACSA program may be less reliable compared to manual analysis for VL ACSA but displayed similar reliability for EI. In addition, the results demonstrated the automatic program had low error for 10 and 12 MHz.