Non-invasive in vivo marbling quantification helps owners to choose the optimum nutritional management for growing cattle and buyers to more precisely evaluate grown cattle at auctions. When using time-domain proton nuclear magnetic resonance (NMR) relaxometry, it is possible to quantify muscle and fat separately by taking advantage of the difference in the spin–spin relaxation time (T2) between water molecules in muscles and fat molecules, which would contribute to the non-invasive and objective determination of marbling scores. With this in mind, we developed a prototype NMR scanner (4.1 MHz for protons) using an original single-sided magnetic circuit and a plane radio frequency (RF) coil for use in the non-invasive quantification of water and fat in live cattle. The sensed region of the developed scanner is compact and almost cubical (19 × 19 × 16 mm3) while the investigation depth (the distance from the RF coil to the center of the sensed region) has been lengthened to 30 mm, which is sufficient for the in vivo trapezius muscle measurement of live cattle. Measurements of 17 samples of beef meat blocks kept at 39 °C were taken in a laboratory to successfully obtain the calibration lines used to convert the NMR signals into water and fat weight fractions at correlation coefficients in excess of 0.9. We also showed that each meat sample could be measured in about 10 s with a measurement error as small as approximately 10 wt%. Accordingly, we believe that our prototype scanner would be useful for in vivo marbling measurements of live cattle trapezius muscles.

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用于活牛大理石纹活体量化的单面核磁共振扫描仪的开发

非侵入性活体大理石花纹量化有助于业主为生长牛选择最佳营养管理，买家在拍卖中更准确地评估生长牛。当使用时域质子核磁共振 (NMR) 弛豫测量法时，可以利用肌肉中的水分子和脂肪分子之间的自旋-自旋弛豫时间 (T2) 的差异来分别量化肌肉和脂肪，这将有助于非侵入性和客观地确定大理石花纹分数。考虑到这一点，我们使用原始单侧磁路和平面射频 (RF) 线圈开发了原型 NMR 扫描仪（质子为 4.1 MHz），用于对活牛的水和脂肪进行非侵入性量化。开发的扫描仪的感测区域紧凑且几乎呈立方体（19 × 19 × 16 mm3），而调查深度（从射频线圈到感测区域中心的距离）已加长至 30 mm，足以满足活牛体内斜方肌测量。在实验室中对 17 个保持在 39 °C 的牛肉块样品进行测量，以成功获得校准线，用于将 NMR 信号转换为相关系数超过 0.9 的水和脂肪重量分数。我们还表明可以在大约 10 秒内测量每个肉样品，测量误差小至约 10 wt%。因此，我们相信我们的原型扫描仪可用于活牛斜方肌的体内大理石花纹测量。