Development of an instrument for temporal and spatial analyses of distribution of muscle oxygenation using near-infrared spectroscopy and its applications

本研究开发了一种基于空间分辨近红外光谱(SR-NIRS)的小型轻量化肌肉氧合实时成像仪器。根据运动试验中肌肉氧合的时间和空间分析结果，我们阐明了肌肉氧合变化与代谢之间的关系，并建立了近红外光谱作为肌肉功能成像的标准技术的基础。取得了以下研究成果：1.基于空间分辨近红外的肌肉氧合成像仪的研制构建了具有足够S/N的紧凑型多通道光学探头。通过液体组织模拟体模实验(血液和Intralipid)验证了探针的测量可靠性。此外，还编写了仪器控制、数据采集和用户界面程序。使用32个探头(3个通道×32个探头=96个通道)时的数据采集时间，包括OX…的计算时间更长的时间，大约是500ms。因此，实时成像运动过程中肌肉氧合的瞬时变化是可能的。人体运动测试中的时间和空间分析该仪器用于分析不同运动时组织氧饱和度(TOS)的时间和空间变化。在运动方案稍有修改的运动测试中(例如，没有或有腿部挤压动作的伸膝运动)，检测到股四头肌TOS的空间和时间差异。此外，还研究了重复运动(两种相似方案)时氧债对胫前肌耗氧率(Vo2)的影响，并比较了前后运动时Vo2的变化。由于氧缺乏，如果TOS在运动过程中没有明显下降，则后一次运动的VO2值是前一次运动的VO2值的直接总和。利用显微光谱仪测量肌肉血氧饱和度构建了一个显微光谱分析系统，该系统使用(I)400-850 nm波长范围内的光来测量光密度(光衰减)，(Ii)用多元回归分析来消除散射成分。利用该系统对大鼠提睾肌的血氧饱和度进行了成像。半径约为10μm的血管的血氧饱和度可以使用约500 nm的波长进行充分成像。然而，为了成像半径较小的血管的血氧饱和度，需要较短的波长(400到500 nm范围)。在实际应用中利用SR-NIR的其他技术使用高灵敏度的CCD摄像机来代替上述多通道光学探头，以验证SR-NIR所基于的高散射介质的扩散近似解的适当性。此外，还构建了易于操作和长期稳定的固体塑料体模，其光学特性与人体组织在近红外波长范围内的光学特性相匹配。预计这些模体将在未来用于校准为运动和康复医学中的实际应用而设计的成像仪器。较少

In this study, a small and lightweight instrument based on spatially resolved near-infrared spectroscopy (SR-NIRS) was developed for real-time imaging of muscle oxygenation. From the results of temporal and spatial analyses of muscle oxygenation during exercise tests, we elucidated the relationship between changes in muscle oxygenation and metabolism and established the basics of NIRS as a standard technique for functional imaging of muscle. The following results were obtained.1. Development of an imaging instrument for muscle oxygenation based on spatially resolved NIRSCompact multi-channel optical probes with sufficient S/N were constructed. The measurement reliability of the probes was validated using a liquid tissue-mimic phantom experiment (blood and Intralipid). In addition, instrumentation control, data acquisition and user-interface programs were coded. The data acquisition time when 32 probes (3 channel X 32 probes = 96 channels) were used, including time for calculation of ox … More ygenation, was about 500 ms. Therefore, real-time imaging of instantaneous changes in muscle oxygenation during exercise is possible.2. Temporal and spatial analyses during exercise tests using human subjectsThe developed instrument was used to analyze temporal and spatial changes in tissue oxygen saturation (TOS) in response to different exercises. Spatial and temporal differences in TOS of the quadriceps muscle during exercise tests with small modifications in exercise protocol (e.g., knee extension exercise without or with leg press action) were detected. In addition, the influence of oxygen debt on oxygen consumption rate ( Vo2) of the tibialis anterior muscle during repeated exercise (two similar protocols) was investigated, with comparison of Vo2 during the former and latter exercises. Due to oxygen debt, the VO2 values of the latter exercise are a direct summation of those of the former exercise if TOS did not decrease significantly during exercise.3. Measurement of oxygen saturation of muscle using micro-spectroscopyA micro-spectroscopy system that uses (i) light in the wavelength range of 400 to 850 nm to measure optical density (light attenuation) and (ii) multiple regression analysis to eliminate the scattering component was constructed. Using this system, imaging of oxygen saturation of the cremaster muscle of a rat was performed. Oxygen saturation of blood vessels with radii of about 10 μm can be sufficiently imaged using wavelengths around 500 nm. However, shorter wavelengths (400 to 500 nm range) are needed in order to image oxygen saturation of blood vessels with smaller radii.4. Other techniques for utilizing SR-NIRS in practical applicationsA highly-sensitive CCD camera was used in place of the multi-channel optical probes described above to validate the appropriateness of the solution of diffusion approximation for a highly scattered medium, in which SR-NIRS is based on. In addition, solid plastic phantoms which are easy to handle and stable over a long period, with optical properties matched to those of human tissue over a range of near-infrared wavelengths, were constructed. It is expected that these phantoms will be used in the future to calibrate imaging instruments designed for practical applications in sports and rehabilitation medicine. Less