Akter Sharmin, Maejima Satoshi, Kawauchi Satoko, Sato Shunichi, Hinoki Akinari, Aosasa Suefumi, Yamamoto Junji, Nishidate Izumi
Tokyo University of Agriculture and Technology, Graduate School of Bio-Application and Systems Engineering, 2-24-16, Naka-cho, Koganei, Tokyo 184-8588, Japan.
National Defense Medical College, Department of Surgery, 3-2, Namiki, Tokorozawa, Saitama 359-8513, Japan.
J Biomed Opt. 2015 Jul;20(7):076010. doi: 10.1117/1.JBO.20.7.076010.
Diffuse reflectance spectroscopy (DRS) has been extensively used for characterization of biological tissues as a noninvasive optical technique to evaluate the optical properties of tissue. We investigated a method for evaluating the reduced scattering coefficient μ(s)', the absorption coefficient μ(a), the tissue oxygen saturation StO₂, and the reduction of heme aa3 in cytochrome c oxidase CcO of in vivo liver tissue using a single-reflectance fiber probe with two source-collector geometries. We performed in vivo recordings of diffuse reflectance spectra for exposed rat liver during the ischemia-reperfusion induced by the hepatic portal (hepatic artery, portal vein, and bile duct) occlusion. The time courses of μ a at 500, 530, 570, and 584 nm indicated the hemodynamic change in liver tissue as well as StO₂. Significant increase in μ(a)(605)/μ(a)(620) during ischemia and after euthanasia induced by nitrogen breathing was observed, which indicates the reduction of heme aa3, representing a sign of mitochondrial energy failure. The time courses of μ(s)' at 500, 530, 570, and 584 nm were well correlated with those of μ(a), which also reflect the scattering by red blood cells. On the other hand, at 700 and 800 nm, a temporary increase in μ(s)' and an irreversible decrease in μ(s)' were observed during ischemia-reperfusion and after euthanasia induced by nitrogen breathing, respectively. The change in μ(s)' in the near-infrared wavelength region during ischemia is indicative of the morphological changes in the cellular and subcellular structures induced by the ischemia, whereas that after euthanasia implies the hepatocyte vacuolation. The results of the present study indicate the potential application of the current DRS system for evaluating the pathophysiological conditions of in vivo liver tissue.
漫反射光谱法（DRS）作为一种用于评估组织光学特性的非侵入性光学技术，已被广泛用于生物组织的表征。我们研究了一种使用具有两种源 - 收集器几何结构的单反射光纤探头来评估体内肝脏组织的约化散射系数μ(s)'、吸收系数μ(a)、组织氧饱和度StO₂以及细胞色素c氧化酶CcO中血红素aa3还原情况的方法。我们在肝门（肝动脉、门静脉和胆管）闭塞诱导的缺血再灌注过程中，对暴露的大鼠肝脏进行了漫反射光谱的体内记录。500、530、570和584 nm处μ(a)的时间进程表明了肝脏组织的血流动力学变化以及StO₂情况。在缺血期间以及氮气呼吸诱导安乐死后，观察到μ(a)(605)/μ(a)(620)显著增加，这表明血红素aa3减少，代表线粒体能量衰竭的迹象。500、530、570和584 nm处μ(s)'的时间进程与μ(a)的时间进程高度相关，这也反映了红细胞的散射情况。另一方面，在700和800 nm处，分别在缺血再灌注期间和氮气呼吸诱导安乐死后观察到μ(s)'暂时增加和不可逆下降。缺血期间近红外波长区域μ(s)'的变化表明缺血诱导的细胞和亚细胞结构的形态变化，而安乐死后的变化意味着肝细胞空泡化。本研究结果表明当前的DRS系统在评估体内肝脏组织病理生理状况方面的潜在应用。
