Validity of ultrasound imaging for intrinsic foot muscle cross-sectional area measurements demonstrated by strong agreement with MRI.

PURPOSE: Intrinsic foot muscles maintain foot structural integrity and contribute to functional movement, posture and balance. Thus, assessing intrinsic foot muscle size and strength are important. Magnetic resonance imaging (MRI) has been shown to accurately image the individual muscles but is costly and time consuming. Ultrasound (US) imaging may provide an alternative that is less costly and more readily available. The purpose of this study was to investigate the validity and intratester reliability of US imaging in measuring intrinsic foot muscle size in comparison to MRI. METHODS: US and MRI were employed to measure the intrinsic foot muscle size involving 35 participants (females = 13; males = 22). The scanned intrinsic foot muscles included the flexor hallucis brevis (FHB), abductor hallucis (ABDH), flexor digitorum brevis (FDB), quadratus plantae (QP) and abductor digiti minimi (ADM). Pearson product correlation (r), intraclass correlation coefficients (ICC), standard error of the measurement (SEm) and minimal detectable difference (MDD) were calculated. RESULTS: High correlations were detected between the US and MRI cross-sectional area (CSA) measurements (r = .971 to 0.995). Test reliability was excellent for both MRI and US (ICC = 0.994 to 0.999). Limits of agreement between MRI and US measurements from ranged from 5.7 to 12.2% of muscle size. SEm values for US ranged from 0.026 to 0.044 cm2, while the SEm for MRI ranged from 0.018 to 0.023 cm2. MDD values for US ranged from 0.073 to 0.122 cm2, while MRI ranged from 0.045 to 0.064 cm2. CONCLUSIONS: US appears to be a valid and reliable alternative to MRI when measuring intrinsic foot muscle CSA. While US is less costly and more readily available, the MRI results were shown to be slightly more precise.

Leg muscle cross-sectional area measured by ultrasound is highly correlated with MRI.

BACKGROUND: The leg muscles are important for balance, posture, and movement during static and dynamic activity. Obtaining cross-sectional area measurements (CSA) of the leg muscles helps researchers understand the health and force production capability of individual leg muscles. Therefore, having an easy to use and readily available method to assess leg muscle CSA is needed. Thus, the purpose of this study was to compare the magnitude, repeatability, and validity of CSA measurements of select leg muscles from ultrasound (US) and the current gold standard, magnetic resonance imaging (MRI). METHODS: 20 healthy volunteers participated in this study. Each participant was imaged via US and MRI. The muscles of interest obtained on each participant consisted of the tibialis anterior at both 30 and 50% of the shank length, tibialis posterior at both 30 and 50% of the shank length, the flexor digitorum longus, the fibularis (peroneus) longus, and the fibularis (peroneus) brevis. RESULTS: Strong Pearson correlations were seen for all of the muscles when comparing US to MRI with a range from .7840 to .9676. For all measurements, standard error of the measurement ranged from .003 to 0.260 cm2. Minimum detectable difference for muscle measurements ranged from .008 cm2 for MRI fibularis longus and fibularis brevis to .693 cm2 for MRI of tibialis anterior at 30%. US minimum detectable difference ranged from .125 cm2 for the tibialis posterior muscle at 30% to .449 cm2 for the tibialis anterior muscle at 50%. CONCLUSIONS: Based on these results ultrasound is a valid method to obtain CSA of muscles of the leg when compared with MRI.

Achilles tendon single bout and season long adaptations during early and late collegiate cross-country season.

AIMS: To examine single bout and season long Achilles tendon cross-sectional area (CSA) changes before and after running during the early and late cross-country season. DESIGN: OBSERVATIONAL: repeated measures design study. SETTING: Controlled laboratory setting. PARTICIPANTS: This study consisted of 35 participants. The running group included 11 males and 9 females, the control group was 8 males and 7 females. MAIN OUTCOME MEASURES: Diagnostic ultrasound images were taken before and after runners completed a common recovery run during the early and late cross-country season. Ultrasound images of control participants, who did not run, were taken following an averaged time that athletes spent running. RESULTS: No significant tendon season long CSA increases occurred for runners (p = 0.453). Runners experienced significant Achilles tendon CSA decreases compared within subjects (p < 0.05) and between controls (p < 0.05). Significant CSA decreases occurred for runners during the early and late season run (p < 0.05) with greater percentages of decrease in the early season (p = 0.009). Male and female runners experienced similar CSA decreases while running (p = 0.696). CONCLUSIONS: No Achilles tendon CSA increases occurred over the season. Significant Achilles tendon CSA decreases occurred while running during early and late season runs, but varied with larger CSA decreases occurring during the early season.