An analysis of the validity and reliability of handheld ultrasound device for measuring rectus femoris muscle size

Background: Previous studies show that ultrasound is valid and reliable when measuring muscle size. A Philips handheld ultrasound device was released in April 2015. The aim of this study was to investigate the validity and reliability of the handheld ultrasound device compared to a conventional ultrasound device, when measuring the size of the rectus femoris (RF). Methods: Two sonographers scanned 39 volunteers (mean age=29.3y, 26 female), once with the Toshiba SSA-660A (regular) ultrasound device and twice with the Philips hand held VISIQ device. The size of the RF (expressed in cross sectional area (CSA) was measured two ways; using the trackball on the Toshiba device and an automatic region of interest on the VISIQ device (method 1), and an ellipse on both devices using the formula π*half width*half length (method 2).Results: Method 1 resulted in an intraclass correlation coefficient (ICC) of .811 with a 95% (confidence interval) CI of .773-.837 (inter-rater reliability) and .907 with a 95% CI of .822-.951 (validity). The ICCs of method 2 were .787 with a 95% CI of .593-.888 (inter-rater reliability) and .867 with a 95 % CI of .746-.930 (validity). Conclusion: VISIQ is a valid and reliable device for measuring RF-CSA. In clinical practice VISIQ could be used for measuring RF-CSA, consequently it could be an economical and easily portable technology for use in both clinical and residential setting