一种多模态脑电和近红外光谱联合采集头盔设计及实验研究

多模式脑—机接口和多模式脑功能成像是目前和未来的发展趋势。本研究针对基于脑电-近红外光谱(EEG-NIRS)的多模态脑—机接口,为同时采集运动区的脑活动,设计了一种EEG和NIRS联合采集的头盔并进行实验验证。根据10-20系统或10-20扩展系统、NIRS探头和EEG电极直径和间距,以C3或C4为基准电极对近红外探头进行对准,把EEG电极置于NIRS电极之间,同时测量同一功能脑区NIRS变化和与之对应的EEG变化;采用螺纹旋紧的方式耦合近红外探头夹持器和近红外探头。为验证该多模态EEG-NIRS联合采集头盔的可行性和有效性,在涉及右手握力和握速运动想象共6个任务期间,采集了6个健康被试运动区的NIRS和EEG信号。这些信号在一定程度上可能反映了握力和握速运动想象相关的脑活动。实验表明本文设计的EEG和NIRS联合采集头盔可行并有效,不仅能够为基于EEG-NIRS的多模态运动想象脑—机接口提供支持,也可望为EEG-NIRS多模态脑功能成像研究提供支持。     

帕金森大鼠纹状体区近红外光谱活体微创在位检测研究

目的:探讨近红外光谱技术(NIRS)测量帕金森(PD)大鼠纹状体区局部优化散射系数(μs')与局部脑血容量(rCBV)的特点.方法:利用光学探头微创测量40只模型组大鼠毁损侧与健侧纹状体区的μs'与rCBV,并与20只假手术组和20只正常组大鼠双侧纹状体测量结果进行比较.结果:模型组毁损侧μs'与rCBV值分别与模型组...     

线性回归算法提取脉搏血氧特征值初步验证

目的:准确提取脉搏血氧信号特征值R是计算脉搏血氧饱和度的关键。传统的R值提取算法大多采用脉搏波的峰谷值法,需要多个周期的平均来提高精度,存在移动步长难以确定、实时性差等缺点。本文提出一种动态实时的R值提取算法。方法:基于近红外光谱技术(Near infrared spectroscopy,NIRS)的测量原理,建立了红外光(IR)和红光(RD)两束透射光强信号的线性回归模型,并确定回归系数b与特征值R之间的定量关系。以纯数字医用放大器为实验平台,搭建了光源驱动电路和光电检测电路,采集的光电容积脉搏波(Photoplethysmography,PPG)信号由蓝牙USB接口传输至计算机,然后进行线性相关性分析及提取算法验证。结果:分析发现IR和RD两束透射光强信号之间具有很强的相关性(r>0.9),运用线性回归法提取的特征值R可以准确的反映正常血氧饱和度值以及在主动闭气过程中血氧饱和度的下降过程。结论:初步验证结果表明,线性回归算法可以有效的进行脉搏血氧信号特征值的动态估算。     

近红外透射法的葡萄糖水溶液的浓度测量和分析

葡萄糖浓度测量是无创检测人体血糖浓度的基础研究,具有重要的科学意义。本研究利用近红外光谱技术（NIRS）和回归定标方法相结合测定葡萄糖水溶液浓度。实验采用傅里叶光谱仪对葡萄糖溶液的近红外透射光谱进行采集,利用光谱数据建立回归模型,讨论偏最小二乘法（PLS ）校正模型中主因子数的确定方法,并对不同预处理方法对PLS模型建立影响进行了研究。采用Savitzky-Golay 卷积平滑对溶液样品吸光度光谱进行预处理,通过交叉验证方法求取预测残差平方和（PRESS）,葡萄糖溶液浓度预测值的最大相对误差限制在了8％以内。研究结果表明,近红外透射法用于葡萄糖水溶液浓度测量能够达到一定的测试精度,具有进一步的研究价值。     

近红外光谱技术在临床检测中的应用

近红外光谱（near infrared spectroscopy,NIRS）分析技术是近年来发展最快、最引人注目的 分析技术,广泛应用于石油、化工、食品等分析化学各领域.本文在介绍NIRS技术基本原理、技术特点的基础上,阐述了NIRS技术在临床检测领域的研究情况,主要包括在无创血糖监测、无创血氧测量、乳腺肿块检测、尿液成分分析等方面的应用与进展,最后初步探讨了该技术在应用中存在的局限性,并对NIRS分析技术在临床检测领域中的应用前景进行了展望.     

基于高频中值滤波的小波滤波在脑动脉色素浓度谱特征信号提取中的应用

近年来,近红外光谱技术(mear infrared spectrometry,NIRS)在脑科学研究领域倍受青睐。为了更好地满足参数的后续使用并提取出有效特征信号,前期尝试了多种常用滤波方法,为了解决滤后信号易失真以及不能有效滤除低频或者高频噪声的问题,提出了基于高频中值滤波的小波滤波,并采用高度还原真实信号特点的仿真信号以及利用脑血流动力学参数采集系统获得的真实光电容积脉搏波(photoplethysmography,PPG)信号,基于中值滤波的小波滤波进行分析。将实验测试数据与其他滤波方法的特征信号提取效果进行对比,并对处理数据进行信噪比和频谱分析。结果表明,采用中值滤波与小波滤波相结合的滤波方式,对脑动脉色素浓度谱特征信号进行滤波处理,能获得有效、精准的脑血流动力学参数,为后续的测量精度打下基础。该方法有效结合了中值滤波能够剔除粗差的特性和小波滤波在光电容积脉搏波中有效滤除高斯信号的特性,改善了采用单一方式的局限性,提供了一种新的PPG滤波的思路,对比传统方法更加优化。     

高光谱成像结合化学计量学诊断胃癌组织

目的:高光谱成像具有光谱和成像的双重功能,这种特性使得高光谱成像能够同时提供实验对象的光谱(即化学信息)和图像(即物理信息)特征。文章探讨了利用高光谱成像技术结合化学计量学方法诊断胃癌组织的可行性及科学性。方法:利用近红外高光谱成像系统获取胃癌组织及正常组织的高光谱图像,利用化学计量学从中提取肿瘤及正常组织的特征光谱并进行光谱归属,然后结合多种目标识别算法自动提取胃癌肿瘤目标,最后利用图像融合技术对识别结果进行形象直观展示,形成高光谱图像诊断胃癌组织的方法体系。结果:正常组织和癌变组织的光谱差异主要体现在950 nm~1050 nm,1150 nm~1250nm和1400 nm~1500 nm三个光谱区域。利用主成分分析降低高光谱数据维度,同时提取了6个最佳波长,即975 nm、1075 nm、1215 nm、1275 nm、1390 nm和1450 nm,利用这些波长作为端元输入可以鉴别肿瘤与正常组织,肿瘤目标检测结果与组织病理学检测结果一致。结论:在化学计量学方法的辅助下,近红外高光谱成像能够诊断胃癌组织。该方法具有客观、快速、准确、无损无创、原位等特点,具有临床应用前景。     

葡萄糖水溶液浓度的近红外光谱测量法--人体血糖浓度无创伤测量方法基础研究

本系统研究了近红外光谱技术与化学计量学理论相结合测定水溶液中葡萄糖浓度的方法。讨论了偏最小二乘法 (PLS)校正模型中光谱范围的优化选择 ,同时也讨论了仪器精度、测量方法与测量精度之间的传递函数 ,给出实现预期测量精度的必要条件。葡萄糖浓度的均方根预测误差 (RMSEP)为 4 .13mg/dL ,浓度测量值与参考值具有良好的相关性 (相关系数为 0 .998)。实验结果表明 :近红外光谱分析方法能够达到一定精度 (RMSEP <5mg/dL) ,具有进一步研究价值。     

精神分裂症生物学病理机制的近红外光谱成像研究(综述)

精神分裂症是一种常见的精神疾病,目前尚缺乏客观的、协助诊断的物理检查指标或工具。近红外光谱成像技术(Near-infrared spectroscopy,NIRS)作为一种新的脑成像技术,已有研究者将其用于精神分裂症患者中进行了大量的研究,旨在探索精神分裂症的生物学病理机制,希望NIRS可以成为一种生物标记来辅助精神分裂症的诊断。本文主要讨论其在精神分裂症研究中的现况,以探究NIRS成为精神分裂症辅助诊断和疗效评估新工具的可能性及应用前景。     

基于近红外光谱法的无创肝储备功能检测

目的针对传统采血法检测肝储备功能存在的有创伤、非实时和易交叉感染等问题,通过分析吲哚氰绿色素、氧合血红蛋白和还原血红蛋白的近红外光谱特性曲线,研究了基于脉搏波光谱分析的无创肝储备功能检测方法。方法利用吲哚氰绿色素在血液中只被肝细胞吸收,其色素浓度呈指数衰减的变化规律,通过静脉注入吲哚氰绿色素,选用波长为940 nm和805 nm的近红外光作为测量入射光,同步采集携带吲哚氰绿浓度变化信息的脉搏波光谱信号,分析光谱信号计算得到血浆消失率和15min滞留率等肝储备功能参数,最后通过6例肝脏患者的常规采血法测得血浆消失率进行对比。结果该方法检测得到的血浆消失率与常规采血法相比,平均相对误差小于5%,该过程除吲哚氰绿色素的注射外不需要再做其他穿刺。结论基于近红外光谱法的无创肝储备功能检测能够准确而实时地检测肝储备功能参数,将为临床肝脏手术提供准确的肝储备功能评估结果。     

Cerebrovascular pattern improved by ozone autohemotherapy: an entropy-based study on multiple sclerosis patients

Ozone major autohemotherapy is effective in reducing the symptoms of multiple sclerosis (MS) patients, but its effects on brain are still not clear. In this work, we have monitored the changes in the cerebrovascular pattern of MS patients and normal subjects during major ozone autohemotherapy by using near-infrared spectroscopy (NIRS) as functional and vascular technique. NIRS signals are analyzed using a combination of time, time–frequency analysis and nonlinear analysis of intrinsic mode function signals obtained from empirical mode decomposition technique. Our results show that there is an improvement in the cerebrovascular pattern of all subjects indicated by increasing the entropy of the NIRS signals. Hence, we can conclude that the ozone therapy increases the brain metabolism and helps to recover from the lower activity levels which is predominant in MS patients.     

Assessment of cerebrovascular resistance with a model of cerebrovascular pressure transmission

A method to assess continuous changes of cerebrovascular resistance based on a biomechanical model of cerebrovascular pressure transmission is developed. Such a method provides an end-point measure to assess new and/or existing management strategies during intensive-care management of patients with brain injury. Changes of both pial arteriolar resistance and cerebrovascular resistance derived by a physiologically based biomechanical model of cerebrovascular pressure transmission, the dynamic relationship between arterial blood pressure (ABP) and intracranial pressure (ICP), were compared to test the validity of the modeling procedure. Pressor challenge was administered to normoxic (N=5) and hypoxic (N=5) piglets equipped with closed cranial windows. Pial arteriolar diameters were used to compute arteriolar resistance. Percent change of pial arteriolar resistance (%DeltaPAR) and percent change of model-derived cerebrovascular resistance (%DeltasCVR) in response to pressor challenge were computed. During intact cerebrovascular regulation and during hypoxia-induced impairment of cerebrovascular regulation, changes in pial arteriolar resistance were accurately predicted by the proposed modeling method designed to assess changes of cerebrovascular resistance.     

Dynamic pressure–flow relationship of the cerebral circulation during acute increase in arterial pressure

The physiological mechanism(s) for the regulation of the dynamic pressure–flow relationship of the cerebral circulation are not well understood. We studied the effects of acute cerebral vasoconstriction on the transfer function between spontaneous changes in blood pressure (BP) and cerebral blood flow velocity (CBFV) in 13 healthy subjects (30 ± 7 years). CBFV was measured in the middle cerebral artery using transcranial Doppler. BP was increased stepwise with phenylephrine infusion at 0.5, 1.0 and 2.0 μg kg^–1 min^–1. Phenylephrine increased BP by 11, 23 and 37% from baseline, while CBFV increased (11%) only with the highest increase in BP. Cerebrovascular resistance index (BP/CBFV) increased progressively by 6, 17 and 23%, demonstrating effective steady-state autoregulation. Transfer function gain at the low frequencies (LF, 0.07–0.20 Hz) was reduced by 15, 14 and 14%, while the phase was reduced by 10, 17 and 31%. A similar trend of changes was observed at the high frequencies (HF, 0.20–0.35 Hz), but gain and phase remained unchanged at the very low frequencies (VLF, 0.02–0.07 Hz). Windkessel model simulation suggests that increases in steady-state cerebrovascular resistance and/or decreases in vascular compliance during cerebral vasoconstriction contribute to the changes in gain and phase. These findings suggest that changes in steady-state cerebrovascular resistance and/or vascular compliance modulate the dynamic pressure–flow relationship at the low and high frequencies, while dynamic autoregulation is likely to be dominant at the very low frequencies. Thus, oscillations in CBFV are modulated not only by dynamic autoregulation, but also by changes in steady-state cerebrovascular resistance and/or vascular compliance.     

Functional near-infrared optical imaging: utility and limitations in human brain mapping

Although near-infrared spectroscopy (NIRS) was developed as a tool for clinical monitoring of tissue oxygenation, it also has potential for neuroimaging. A wide range of different NIRS instruments have been developed, and instruments for continuous intensity measurements with fixed spacing [continuous wave (CW)-type instruments], which are most readily available commercially, allow us to see dynamic changes in regional cerebral blood flow in real time. However, quantification, which is necessary for imaging of brain functions, is impossible with these CW-type instruments. Over the past 20 years, many different approaches to quantification have been tried, and several multichannel time-resolved and frequency-domain instruments are now in common use for imaging. Although there are still many problems with this technique, such as incomplete knowledge of how light propagates through the head, NIRS will not only open a window on brain physiology for subjects who have rarely been examined until now, but also provide a new direction for functional mapping studies.     

Application of near infrared spectroscopy to exercise sports science.

Over the past 15 years the use of near infrared spectroscopy in exercise and sports science has increased exponentially. The majority of these studies have used this noninvasive technique to provide information related to tissue metabolism during acute exercise. This has been undertaken to determine its utility as a suitable tool to provide new insights into the heterogeneity and regulation of local tissue metabolism, both in cerebral and skeletal muscle tissue. In the accompanying articles in this symposium, issues related to the principles, techniques, limitations (Ferrari et al., 2004), and reliability and validity of NIRS in both cerebral and skeletal muscle tissue (Bhaambhani, 2004), mostly during acute exercise, have been addressed and will not be discussed here. Instead, the present paper will focus specifically on the application of NIRS to exercise sports science, with an emphasis on how this technology has been applied to exercise training and sport, and how it can be used to design training programs for athletes.     

Near-infrared spectroscopy/imaging for monitoring muscle oxygenation and oxidative metabolism in healthy and diseased humans

Near-infrared spectroscopy (NIRS) was initiated in 1977 by Jobsis as a simple, noninvasive method for measuring the presence of oxygen in muscle and other tissues in vivo. This review honoring Jobsis highlights the progress that has been made in developing and adapting NIRS and NIR imaging (NIRI) technologies for evaluating skeletal muscle O(2) dynamics and oxidative energy metabolism. Development of NIRS/NIRI technologies has included novel approaches to quantification of the signal, as well as the addition of multiple source detector pairs for imaging. Adaptation of NIRS technology has focused on the validity and reliability of NIRS measurements. NIRS measurements have been extended to resting, ischemic, localized exercise, and whole body exercise conditions. In addition, NIRS technology has been applied to the study of a number of chronic health conditions, including patients with chronic heart failure, peripheral vascular disease, chronic obstructive pulmonary disease, varying muscle diseases, spinal cord injury, and renal failure. As NIRS technology continues to evolve, the study of skeletal muscle function with NIRS first illuminated by Jobsis continues to be bright.     

Interplay of tumor vascular oxygenation and tumor pO2 observed using near-infrared spectroscopy,an oxygen needle electrode,and 19F MR pO2 mapping

This study investigates the correlation of tumor blood oxygenation and tumor pO(2) with respect to carbogen inhalation. After having refined and validated the algorithms for calculating hemoglobin concentrations, we used near-infrared spectroscopy (NIRS) to measure changes of oxygenated hemoglobin concentration (delta[HbO(2)]) and used an oxygen needle electrode and (19)F MRI for pO(2) measurements in tumors. The measurements were taken from Dunning prostate R3327 tumors implanted in rats, while the anesthetized rats breathed air or carbogen. The NIRS results from tumor measurements showed significant changes in tumor vascular oxygenation in response to carbogen inhalation, while the pO(2) electrode results showed an apparent heterogeneity for tumor pO(2) response to carbogen inhalation, which was also confirmed by (19)F MR pO(2) mapping. Furthermore, we developed algorithms to estimate hemoglobin oxygen saturation, sO(2), during gas intervention based on the measured values of delta[HbO(2)] and pO(2). The algorithms have been validated through a tissue-simulating phantom and used to estimate the values of sO(2) in the animal tumor measurement based on the NIRS and global mean pO(2) values. This study demonstrates that the NIRS technology can provide an efficient, real-time, noninvasive approach to monitoring tumor physiology and is complementary to other techniques, while it also demonstrates the need for an NIR imaging technique to study spatial heterogeneity of tumor vasculature under therapeutic interventions.     

Functional near-infrared spectroscopy: current status and future prospects

Near-infrared spectroscopy (NIRS), which was originally designed for clinical monitoring of tissue oxygenation, has been developing into a useful tool for neuroimaging studies (functional near-infrared spectroscopy). This technique, which is completely noninvasive, does not require strict motion restriction and can be used in a daily life environment. It is expected that NIRS will provide a new direction for cognitive neuroscience research, more so than other neuroimaging techniques, although several problems with NIRS remain to be explored. This review demonstrates the strengths and the advantages of NIRS, clarifies the problems, and identifies the limitations of NIRS measurements. Finally, its future prospects are described.     

Cerebrovascular permeability and cognition in the aging rat.

Regional cerebrovascular permeability-capillary surface area products (rPS) and brain vascular space (BVS) were measured in aging, conscious, unrestrained Sprague-Dawley rats. Three groups of animals were examined: young-mature (6 months), middle-aged (12-14 months), and old (24-26 months) rats. Complex maze learning had been previously characterized in these same animals. Maze learning declined with age. Brain vascular space did not differ significantly with age in any brain region. However, small, but significant age-dependent decreases in rPS (25-33%) were observed. These decreases occurred mainly in the old animals in the basal ganglia and parietal cortex, and in the middle-aged and old rats in the olfactory bulbs. Significant and unexpected positive average correlations between brain permeability-capillary surface area products (PS) and learning errors occurred primarily in young rats and were attributable mainly to changes in 5 of 14 brain regions; hypothalamus, hippocampus, parietal cortex, septal area and superior colliculus. The higher correlations between maze learning errors and PS in young animals may indicate dynamic regulation of this cerebrovascular parameter which is lessened with aging. Average correlations between PS and cerebral blood flow also were determined and found to be generally small and not significant for most brain regions and age groups.     

Tumour oxygen dynamics measured simultaneously by near-infrared spectroscopy and 19F magnetic resonance imaging in rats

Simultaneous near-infrared spectroscopy (NIRS) and magnetic resonance imaging (MRI) were used to investigate the correlation between tumour vascular oxygenation and tissue oxygen tension dynamics in rat breast 13762NF tumours with respect to hyperoxic gas breathing. NIRS directly detected global variations in the oxygenated haemoglobin concentration (Delta[HbO(2)]) within tumours and oxygen tension (pO(2)) maps were achieved using (19)F MRI of the reporter molecule hexafluorobenzene. Multiple correlations were examined between rates and magnitudes of vascular (Delta[HbO(2)]) and tissue (pO(2)) responses. Significant correlations were found between response to oxygen and carbogen breathing using either modality. Comparison of results for the two methods showed a correlation between the vascular perfusion rate ratio and the mean pO(2) values (R(2) > 0.7). The initial rates of increase of Delta[HbO(2)] and the slope of dynamic pO(2) response, d(pO(2))/dt, of well-oxygenated voxels in response to hyperoxic challenge were also correlated. These results demonstrate the feasibility of simultaneous measurements using NIRS and MRI. As expected, the rate of pO(2) response to oxygen is primarily dependent upon the well perfused rather than poorly perfused vasculature.