Spatial frequency analysis (SFA) is a quantitative ultrasound method that characterizes tissue organization. SFA has been used for research involving tendon injury, but may prove useful in similar research involving skeletal muscle. As a first step, we investigated if SFA could detect known architectural differences within hamstring muscles. Ultrasound B-mode images were collected bilaterally at locations corresponding to proximal, mid-belly, and distal thirds along the hamstrings from 10 healthy participants. Images were analyzed in the spatial frequency domain by applying a two-dimensional Fourier Transform in all 6.5 × 6.5 mm kernels in a region of interest corresponding to the central portion of the muscle. SFA parameters (peak spatial frequency radius [PSFR], maximum frequency amplitude [Mmax], sum of frequencies [Sum], and ratio of Mmax to Sum [Mmax%]) were extracted from each muscle location and analyzed by separate linear mixed effects models. Significant differences were observed proximo-distally in PSFR (p = .039), Mmax (p < .0001), and Sum (p < .0001), consistent with architectural descriptions of the hamstring muscles. These results suggest that SFA can detect regional differences of healthy tissue structure within the hamstrings—an important finding for future research in regional muscle structure and mechanics.

空间频率分析 (SFA) 是表征组织组织的定量超声方法。SFA 已被用于涉及肌腱损伤的研究，但在涉及骨骼肌的类似研究中可能证明是有用的。作为第一步，我们调查了 SFA 是否可以检测到腘绳肌中已知的结构差异。从 10 名健康参与者沿着腘绳肌在对应于近端、中腹部和远端三分之一的位置双侧收集超声 B 模式图像。通过在与肌肉中心部分对应的感兴趣区域中的所有 6.5 × 6.5 mm 内核中应用二维傅立叶变换，在空间频域中分析图像。SFA 参数（峰值空间频率半径 [PSFR]、最大频率幅度 [Mmax]、频率总和 [Sum]、和 Mmax 与总和的比率 [Mmax%]) 从每个肌肉位置提取，并通过单独的线性混合效应模型进行分析。在 PSFR 近端观察到显着差异（p  = .039)、Mmax ( p  < .0001) 和 Sum ( p  < .0001)，与腘绳肌的结构描述一致。这些结果表明，SFA 可以检测腘绳肌内健康组织结构的区域差异——这是未来区域肌肉结构和力学研究的重要发现。