Effect of transducer scanning velocity during extended field of view imaging acquisition on pennate and fusiform muscles echo intensity.

PURPOSE: This study investigated the effects of transducer scanning velocity on echo intensity (EI) of muscles with different architectures [biceps brachii (BB), vastus lateralis (VL), and tibialis anterior (TA)] and determined interrater reliability across velocities. METHODS: Ideal transducer velocity for each muscle was determined by the ultrasound system and measured using reflective markers and video analysis. Fast and slow velocities were set at ±50% of the ideal velocity (i.e., control condition). Three images per velocity were collected in 40 participants, with speed controlled by a digital metronome. EI, adipose, and superficial tissue thicknesses were analyzed by two blinded raters using ImageJ®. Repeated-measures ANOVA with Tukey post hoc test were applied for absolute and percentage values. Reliability was assessed using intraclass correlation coefficients (ICC), standard error of measurement (SEM), and minimum detectable change (MDC). RESULTS: Interrater reliability was excellent for all muscles and velocities (r ≥ 0.933). Significant differences were observed only in TA. Slow velocity produced higher EI in TA's superior compartment compared with control and fast conditions (5% and 6%, respectively), and higher EI in the inferior compartment compared with fast velocity (4%). However, all differences were within the SEM and below the MDC. No significant differences were observed in BB or VL. CONCLUSION: Transducer scanning velocity affects EI measurements in TA compartments, particularly under slow conditions, although these differences may not represent true physiological changes. In contrast, BB and VL measurements were unaffected, and all velocities demonstrated excellent interrater reliability.