RELIABILITY OF ULTRASOUND IMAGING OF THE MEDIAL GASTROCNEMIUS IN A LOADED AND UNLOADED POSITION

Lauren E. Pacinelli, Jeffrey A. Williams, Ryan M. Thiele; Kansas State University, Manhattan, KS PURPOSE: Determine the reliability of ultrasonography (US) characteristics (pennation angle; PA, muscle thickness; MT, fascicle length; FL, echo intensity; EILong) of the medial gastrocnemius (MG) during unloaded (ULD) and loaded (LD) positions. METHODS: Twelve healthy females (mean±SD: age = 19.42 ± 1.16 years) volunteered for this investigation on 2 non-consecutive days at the same time of day (±2h). During each visit, participants were placed in the ULD position (laying prone on an examination table with the low leg extended) and a LD position (standing with their weight shifted on to the right leg). All US images were gathered from the same region of interest of the MG marked consistently on the skin of the right low leg. US probe placement was determined at 1/3 the low leg circumference at 10cm distal to the tibial tuberosity and was maintained for every measurement. ULD assessments were performed after participants had rested for 5 min to allow for fluid shifts to stabilize. Two longitudinal images were obtained from both ULD and LD positions on each visit. US images of the MG were optimized for image quality, including gain (50dB), depth (6cm), and frequency (10MHz) and were set prior to testing and held constant between participants and across trials. Reliability calculations were determined using intra-class correlation coefficient (ICC, model 2,1) and standard error of measurement (SEM) also reported as a percentage (SEM%). Systematic variability was examined using separate one-way repeated measures analyses of variance (ANOVAs). RESULTS: The ANOVAs indicated no systematic variability in any of the dependent variables (P \u3e 0.05). The ICCs and SEM values expressed as a percentage of the mean for ULPA, MT, FL, EILong, ranged from 0.980-0.996 and 4.132-10.264%, respectively (Table 1). CONCLUSION: Overall, these finding suggest that US imaging of the MG in an ULD and LD position may be a reliable and beneficial technique for practical examinations of muscle architecture