R&D Division, Meiji Co., Ltd., Hachiouji, Tokyo, Japan.
Department of Molecular Imaging and Theranostics, Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Inage, Chiba, Japan.
PLoS One. 2024 Jul 30;19(7):e0305620. doi: 10.1371/journal.pone.0305620. eCollection 2024.
Although the standard method to evaluate skeletal muscle protein synthesis (MPS) is muscle biopsy, the method is invasive and problematic for multisite use. We conducted a small pilot study in volunteers to investigate changes in MPS according to skeletal muscle site using a noninvasive method in which 6 healthy young men were given yogurt (containing 20 g milk protein) or water, and 1 h later, l-[11C]methionine ([11C]Met) was administered intravenously. Dynamic PET/CT imaging of their thighs was performed for 60 min. The influx constant Ki of [11C]Met in skeletal muscle protein was calculated as an index of MPS using a Patlak plot, and found to be 0.6%-28% higher after ingesting yogurt than after water in 5 of the 6 volunteer participants, but it was 34% lower in the remaining participant. Overall, this indicated no significant increase in Ki after ingesting milk protein. However, when the quadriceps and hamstring muscles were analyzed separately, we found a significant difference in Ki. This demonstrates the potential of visualizing MPS by calculating the Ki for each voxel and reconstructing it as an image, which presents unique advantages of [11C]Met PET/CT for evaluating MPS, such as site-specificity and visualization.
虽然评估骨骼肌蛋白质合成 (MPS) 的标准方法是肌肉活检，但该方法具有侵入性，并且在多部位使用时存在问题。我们在志愿者中进行了一项小型试点研究，使用非侵入性方法根据骨骼肌部位研究 MPS 的变化，6 名健康年轻男性给予酸奶（含 20 克牛奶蛋白）或水，1 小时后静脉给予 l-[11C]蛋氨酸 ([11C]Met)。对他们的大腿进行 60 分钟的动态 PET/CT 成像。使用 Patlak 图计算骨骼肌蛋白中 [11C]Met 的流入常数 Ki，作为 MPS 的指标，结果发现，与水相比，6 名志愿者中有 5 名在摄入酸奶后 Ki 增加了 0.6%-28%，但在其余 1 名参与者中 Ki 降低了 34%。总体而言，这表明摄入牛奶蛋白后 Ki 没有显著增加。然而，当分别分析股四头肌和腘绳肌时，我们发现 Ki 存在显著差异。这表明通过计算每个体素的 Ki 并将其重建为图像，可以可视化 MPS，[11C]Met PET/CT 具有评估 MPS 的独特优势，例如部位特异性和可视化。
