Author(s): Steven Ball, Ike Edwards
Mentor(s): Brent Feland
Institution BYU
BACKGROUND: Shear Wave Elastography (SWE) is increasingly being used to assess muscle stiffness, yet there is limited information on the consistency of SWE measurements across different muscles, angles, and depths. This gap complicates the selection of optimal angles and muscles for accurate assessment, particularly for large muscles like the quadriceps. PURPOSE: This study aims to evaluate whether pilot measurements can demonstrate consistency in quadriceps SWE across two angles over three consecutive days. METHODS: Data were collected from 7 male participants (mean age 21.5 ± 1.5 years; height 182.38 ± 5.0 cm; weight 84.5 ± 6.1 kg) in Provo, Utah, in 2024. Participants were seated with knees at 90° flexion, and scans of the vastus medialis, rectus femoris, and vastus lateralis were conducted using a GE Logiq S8 ultrasound with a 9L probe. SWE measurements were taken at both the upper and lower halves of the muscle depth, with knee flexion, then repeated at 30°. For the vastus lateralis, the exact midway point between the greater trochanter and lateral epicondyle of the femur was scanned. The Vastus Medialis and Rectus Femoris were scanned at their visual centers. Each muscle was assessed on three consecutive days, with five SWE measurements collected from each muscle per day. ANALYSIS: Using Excel and SPSS v29, the consistency within each group (by muscle, angle, and depth) was analyzed by calculating the coefficient of variation (CV) for each kPa measurement. Lower CV values indicated greater measurement consistency. RESULTS AND CONCLUSION: Results indicated that measurements at 30° generally yielded lower CV values than those at 90°, especially on day three. Across muscles, the vastus medialis showed the least variation regardless of depth, while measurements taken at the bottom half of muscle depth were more consistent across days, possibly due to reduced movement in deeper fibers. The vastus lateralis displayed the greatest inconsistency at both depths. Current data is insufficient to definitively identify which angle provides the most consistent day-to-day measurements. An estimated sample size of 63 subjects per group per angle, would be required to achieve adequate statistical power (80%) at a 5% significance level. Therefore, additional data are needed to accurately determine consistency across angles.