Assessment of Quadriceps Muscle Characteristics in Female Division I Athletes: A Validation Study of Wireless Probes Against Standard Ultrasound Units.

Objective: Wireless ultrasound probes offer a quicker, more affordable option for muscle quality assessment compared with standard cart units, yet their effectiveness for evaluating larger muscles such as the rectus femoris in terms of cross-sectional area (CSA) and echo-intensity (EI) is unclear due to limited field of view. This study evaluates whether rectus femoris thickness and EI measured with a wireless probe correlate with CSA and EI obtained from a standard cart ultrasound.

Methods: A cross-sectional, convenience sample of 29 division I college female athletes (age: 20.1 [1.1] y, height: 169.7 [7.4] cm, mass: 69.7 [10.0] kg) were recruited. Panoramic thigh ultrasound images were acquired with a standard ultrasound cart to assess the rectus femoris CSA and EI at 50% of the thigh length. A wireless ultrasound probe was used to acquire stationary images with the knee in the same position to assess rectus femoris thickness and EI. A Pearson product-moment correlation was used to determine the association between the muscle outcomes obtained with the standard cart ultrasound and wireless ultrasound probe.

Results: Standard ultrasound CSA (10.1 [2.0] cm2) and wireless ultrasound thickness (2.0 [0.3] cm) were strongly associated (r = .71, P < .001). Standard ultrasound EI (56.2 [5.1] arbitrary units) and wireless ultrasound EI (62.0 [6.3] arbitrary units) were moderately associated (r = .49, P = .007).

Conclusion: Wireless ultrasound offers a fast and accessible method for assessing muscle thickness in female division I athletes when compared with similar muscle size and quality metrics measured on panoramic images acquired with a standard ultrasound cart. The echogenicity indices from wireless and standard ultrasound are significantly associated between units; however, wireless ultrasound systematically overestimates echogenicity compared with the standard.