Zurich Ultrasound Research and Translation (ZURT), Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zürich, Switzerland.
Deusto Institute of Technology, University of Deusto / IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
Medicine (Baltimore). 2021 Mar 19;100(11):e23576. doi: 10.1097/MD.0000000000023576.
Short-term immobilization leads to fatty muscular degeneration, which is associated with various negative health effects. Based on literature showing very high correlations between MRI Dixon fat fraction and Speed-of-Sound (SoS), we hypothesized that we can detect short-term-immobilization-induced differences in SoS.Both calves of 10 patients with a calf cast on one side for a mean duration of 41 ± 26 days were examined in relaxed position using a standard ultrasound machine. Calf perimeters were measured for both sides. A flat Plexiglas-reflector, placed vertically on the opposite side of the probe with the calf in-between, was used as a timing reference for SoS. SoS was both manually annotated by two readers and assessed by an automatic annotation algorithm. The thickness values of the subcutaneous fat and muscle layers were manually read from the B-mode images. Differences between the cast and non-cast calves were calculated with a paired t test. Correlation analysis of SoS and calf perimeter was performed using Pearson's correlation coefficient.Paired t test showed significant differences between the cast and non-cast side for both SoS (P < .01) and leg perimeter (P < .001). SoS was reduced with the number of days after cast installment (r = -0.553, P = .097). No significant differences were found for muscle layer thickness, subcutaneous fat layer thickness, mean fat echo intensity, or mean muscle echo intensity.Short-term-immobilization led to a significant reduction in SoS in the cast calf compared to the healthy calf, indicating a potential role of SoS as a biomarker in detecting immobilization-induced fatty muscular degeneration not visible on B-mode ultrasound.
短期固定导致脂肪性肌肉变性，与各种负面健康影响有关。基于文献表明磁共振 Dixon 脂肪分数与声速（SoS）之间存在非常高的相关性，我们假设可以检测到 SoS 在短期固定引起的差异。10 名患者的每侧小腿均用小腿石膏固定，平均固定时间为 41±26 天，在放松状态下使用标准超声仪进行检查。测量双侧小腿周长。将一个垂直放置在探头对面的平板有机玻璃反射器放在小腿之间，用作 SoS 的定时参考。SoS 由两位读者手动注释，也由自动注释算法进行评估。从 B 模式图像手动读取皮下脂肪层和肌肉层的厚度值。用配对 t 检验计算石膏固定和非石膏固定小腿之间的差异。使用 Pearson 相关系数进行 SoS 和小腿周长的相关性分析。配对 t 检验显示石膏固定和非石膏固定侧的 SoS（P<0.01）和小腿周长（P<0.001）均存在显著差异。SoS 随石膏安装后天数的增加而降低（r=-0.553，P=0.097）。肌肉层厚度、皮下脂肪层厚度、平均脂肪回波强度或平均肌肉回波强度无显著差异。与健康侧小腿相比，石膏固定侧小腿的 SoS 显著降低，表明 SoS 作为一种生物标志物在检测不可见的 B 型超声引起的脂肪性肌肉变性方面具有潜在作用。
