Radboud University Medical Center, Donders Centre for Neuroscience, Department of Rehabilitation, Nijmegen, The Netherlands.
Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Department of Radiology and Nuclear Medicine, Nijmegen, The Netherlands.
PLoS One. 2019 Apr 29;14(4):e0215276. doi: 10.1371/journal.pone.0215276. eCollection 2019.
This study aimed to elucidate whether muscle activity (in terms of glucose uptake) between the legs can be considered symmetrical during walking. Furthermore, we aimed to determine whether the [18F]-fluorodeoxyglucose was distributed heterogeneously throughout each muscle, and if so, whether areas of high uptake would be clustered.
Ten healthy participants walked on a treadmill at self-selected comfortable walking speed for a total of 90 minutes, 60 minutes before and 30 minutes after intravenous injection of 50 MBq [18F]-fluorodeoxyglucose. Thereafter, a positron emission tomography/computed tomography scan of the lower limb was acquired. Three-dimensional muscle contours of 78 (= 39x2) muscles of the left and right lower limb were semi-automatically determined from magnetic resonance imaging scans. After non-rigid registration, those muscle contours were used to extract [18F]-fluorodeoxyglucose uptake from the positron emission tomography scans.
Large asymmetries were observed in the lower leg muscles (e.g. median absolute asymmetry index of 42% in the gastrocnemius medialis) and in the gluteus minimus (30% asymmetry) and gluteus medius (15% asymmetry), whereas the uptake in the thighs was relatively symmetrical between the limbs (<6% asymmetry). These were not related to limb-dominance nor to inter-limb differences in muscle volume. The [18F]-fluorodeoxyglucose distribution was not distributed normally; most voxels had a relatively low standardized uptake value, and a minority of voxels had a relatively high standardized uptake value. The voxels with higher [18F]-fluorodeoxyglucose uptake were distributed heterogeneously; they were clustered in virtually all muscles.
The findings in this study challenge the common assumption of symmetry in muscle activity between the limbs in healthy subjects. The clustering of voxels with high uptake suggests that even in this prolonged repetitive task, different spatial regions of muscles contribute differently to walking than others.
本研究旨在阐明在行走过程中，双腿的肌肉活动（以葡萄糖摄取为指标）是否可以被认为是对称的。此外，我们还旨在确定[18F]-氟脱氧葡萄糖是否在整个肌肉中分布不均匀，如果是，高摄取区域是否会聚集。
10 名健康参与者在跑步机上以自我选择的舒适步行速度行走，共 90 分钟，在静脉注射 50MBq [18F]-氟脱氧葡萄糖前 60 分钟和后 30 分钟进行。之后，对下肢进行正电子发射断层扫描/计算机断层扫描。从磁共振成像扫描中半自动确定左、右下肢 78 个（=39x2）肌肉的三维肌肉轮廓。在非刚性配准后，从正电子发射断层扫描中提取[18F]-氟脱氧葡萄糖摄取。
小腿肌肉（如比目鱼肌的中位数绝对不对称指数为 42%）和臀小肌（30%不对称）和臀中肌（15%不对称）存在较大的不对称性，而大腿的摄取在肢体之间相对对称（<6%不对称）。这些与肢体优势或肢体间肌肉体积差异无关。[18F]-氟脱氧葡萄糖的分布不均匀；大多数体素的标准化摄取值相对较低，少数体素的标准化摄取值相对较高。具有较高[18F]-氟脱氧葡萄糖摄取的体素分布不均匀；它们几乎在所有肌肉中都聚集在一起。
本研究的发现挑战了健康受试者中肢体肌肉活动对称性的常见假设。高摄取体素的聚类表明，即使在这个长时间重复的任务中，肌肉的不同空间区域对行走的贡献也不同于其他区域。
