基于双波长近红外成像方法的血氧含量检测

Blood Oxygen Content Detection with Dual-Wavelength Near-Infrared Imaging

为了对生物组织血氧含量分布进行成像,利用760 nm和850 nm的双波长近红外差分探测方法,研制了血氧含量检测系统,并首次使用吲哚菁绿(ICG)和散射体作为仿体设计实验。首先测量了牛奶的光密度差ΔOD随牛奶浓度差Δc的变化值。接着将ICG溶解在稀释了40倍的牛奶中,用不同浓度梯度稀释ICG,得到一系列ΔOD-Δc曲线,用一次函数拟合曲线,根据方差(SSE)、均方根(RMSE)和确定系数(R2)确定系统分辨率。然后改变散射介质浓度,研究它对系统测量的影响。最后选择30名健康测试者进行在体实验,测量手掌血氧含量的空间分布以及动态时间变化。结果表明,牛奶和ICG在双波长光源下的吸收系数之比分别接近1∶1和2.5∶1,因此可以用牛奶模拟组织中的水、脂肪、某些色素等,用ICG模拟血液中的脱氧血红蛋白;系统分辨率为1.6×10-5mg/m L的ICG浓度变化;弱散射介质的浓度与系统的动态响应范围成负相关,与系统的灵敏度成正相关;扎住手腕后,手掌血氧含量从1逐渐降低至0.3±0.105,松开橡皮筋后,血氧含量逐渐恢复至0.97±0.018。以上结果说明该系统具有测量可行性,将在组织血氧检测方面拥有良好的应用价值。

In order to image the distribution of blood oxygen content,a blood oxygen content detection system was developed by the near infrared imaging of dual wavelengths 760 nm and 850 nm. A new simulation experiment with indocyanine green and scatterers was conducted. First,we changed the concentration of milkΔC and detected its optical density change（ ΔOD）. Then indocyanine green（ ICG） was dissolved in milk which was diluted 40 times. With gradient dilution of ICG,a series of curves of ΔOD-Δc were obtained. We used a linear function to fit the curves and determined the resolution of the system according to the sum of squares due to error（ SSE）,root mean squared error（ RMSE） and coefficient of determination（ R2）. Third,we changed the concentration of the scattering medium to study its influence on detection. Last,30 healthy subjects were chosen to detect the spatial distribution of blood oxygen content and its dynamic changes. The results showed the absorption coefficient ratio of milk in the dual wavelength light was closed to 1 ∶ 1 and the ratio of ICG was 2. 5 ∶ 1,therefore milk could simulate water,fat and pigment,and ICG could simulate deoxygenated hemoglobin. Furthermore,the system is able to identify the minimum change of the concentration of indocyanine green of 1. 6 × 10^-5mg / m L. With the elevation of the scatters concentration,on one hand,the scope of the system dynamic response became large; on the other hand,the sensitivity of the system became low. Finally,the blood oxygen content decreased from 1 to 0. 3 ± 0. 105 during the stage of tying wrist and then recovered to 0. 97 ± 0. 018 after removing the rubber band. The experiments above demonstrated the potential of application for the system in detecting tissue blood oxygen.