基于激光散斑技术的皮层血管结构与功能成像
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摘要
基于运动颗粒相干散射特征的激光散斑衬比成像技术自上世纪80年代被首次提出后，逐渐应用于生物医学的血流监测中。与常规血流监测设备不是需要注射造影剂就是时空分辨率较低，或者需要逐行扫描才能得到全场图像的缺陷相比，激光散斑成像技术无需扫描即可得到活体的全场、实时、非侵入的高分辨率血流速度分布二维图像。近年来，鉴于其易于在脑生理或病理状态下监测血流的优势，这一血流成像技术正越来越受到神经科学工作者的重视。
本论文研究内容主要涉及激光散斑成像技术在以下三个方面的应用：首先，我们结合内源光信号特征，通过635纳米激光照射所得的散斑图像同时得到了脱氧血红蛋白浓度和脑血流（CBF）变化的信息，并将之应用于不同亚低温对脑血流影响的研究。其次，将激光散斑成像技术应用于脑功能成像，研究了不同体觉刺激引起的血液动力学响应以及低温对脑功能的影响。最后，利用激光散斑成像的高时空分辨率特性实时动态观测了大鼠局灶性脑缺血模型在缺血和再灌过程中不同脑区脑血流变化的差异。此外，考虑到现有散斑成像技术存在着动态范围较狭窄和受心跳、呼吸等噪声影响使其信噪比降低等问题，我们在图像处理的过程中，引入了基于单调点变化的增强散斑衬比分析方法，拓宽了散斑图像的动态范围，提高了可视化效果，而图像配准的方法也能进一步提高图像的空间分辨率。
本论文主要的研究内容和结论如下所述：
1)通过仿真实验验证了两种散斑衬比分析方法（空间域和时域）所得散斑衬比值和实际流速的绝对值之间在一定范围内线性相关。实验结果显示，在0-5毫米/秒的实际流速范围内，散斑衬比和绝对速度间呈较好的线性关系，说明我们的成像系统非常适合脑血流的动态监测。另外，通过动物实验对系统性能和参数进行了分析，为全文后续研究选取合适的系统参数做了前期的实验证明（如曝光时间的选取等）。
2)研究了不同低温下（35℃和32℃）大鼠脑皮层血流速度和脱氧血红蛋白浓度的相对变化情况。亚低温疗法作为辅助治疗脑损伤（包括脑中风、脑创伤、全局性脑损伤等）的手段已被广泛地应用于重症监护病房（ICU），并被证明具有很好的神经保护作用。而在一些疾病的诊断及脑功能研究中，大脑皮层血流的特征模式是非常重要的参数。因此，若能得到不同低温下，高分辨率的大脑皮层血流变化，将具有一定的科学和临床意义。我们利用时域激光散斑对比度分析和内源光信号来监测大鼠在轻度低温（35℃）和中度低温（32℃）下脑皮层血流以及脱氧血红蛋白浓度的变化，并进一步研究了皮层不同血管内（如：动脉、静脉及毛细血管网）血流变化的规律。18只用戊巴比妥钠麻醉的SD雄性大鼠被随机分成轻度和中度低温实验组（每组9只）。分别在基线期（37℃），低温期（35℃或32℃）和复温后期（37℃）三个阶段记录它们的激光散斑图像，然后用ITK（Insight Toolkit）软件包中的图像分割工具提取不同血管，从而研究动脉、静脉和毛细血管在低温下的流速信息。在轻度低温实验组中，所有脑血管中血流速度在35℃和复温状态下显著增加。静脉和毛细血管中脱氧血红蛋白浓度均下降，但是动脉除外。而在中度低温试验组中，低温阶段所有脑血管内血流比基线值下降20%，并在复温至37℃后能够恢复到大约90%的基线水平。各血管内脱氧血红蛋白浓度在此组中无显著变化。考虑到脑皮层血流复温后的恢复情况，中度低温可能更适合临床应用。当然，关于脑皮层血流在血管水平的生理变化机制以及亚低温的神经保护作用仍有待未来进一步的研究。
3)观察了常温和中度低温下大鼠功能性脑血流变化的时空特征。在众多神经功能成像研究中，均将体觉刺激引起的局部脑血流变化作为研究皮层神经元活动的标志参数之一。但迄今为止，关于诱发的局部脑血流变化和神经元活动间的关系特征尚未被详细描述。从我们的结果可以看到，随着刺激幅值（0.5毫安,1.5毫安和2.5毫安）的上升，脑血流灌注也相应增强，这与文献中用激光多普勒血流计在单点采集得到的实验结果相吻合。我们也对大鼠后肢分别给予了1.5毫安，脉宽0.3毫秒，频率5赫兹的持续时间为4秒和8秒的电刺激。结果发现，在持续8秒电刺激的实验组中，局部脑血流变化在达到峰值后跟随一个平台期。这一系列实验结果表明用激光散斑成像技术观察局部脑血流的响应，可以很好地反映功能神经元组整合的活动特征结果。目前，有关温度对功能响应影响的时空变化特征尚不清楚。我们分别记录了8只雄性SD大鼠在常温（37℃）和中度低温（32℃）下的功能激光散斑图像，以研究亚低温对神经元活动的影响。对每一只实验动物的每一个温度阶段，重复十次相同的后肢电刺激协议（2.5毫安,0.3毫秒脉宽,5赫兹,4秒持续时间），每两组协议间至少休息60秒，对10组结果求平均以消除随机噪声的影响。同时，为减少呼吸和心跳对图像的影响，对所有数据经过配准的激光散斑衬比分析，再结合时间簇分析方法，我们发现低温会引起脑血流功能响应峰值的延迟以及响应持续时间的延长。此外，低温会导致功能活动区域面积减小，脑血流峰值降低。而动脉和毛细血管网相较静脉在功能刺激引起的脑血流响应变化中占据更为主导的地位。以上实验结果表明，结合激光散斑成像技术和时间簇分析方法得到的高时空分辨率功能图像，有助于我们更好地了解神经-血管耦合性在正常或病理状态下的时空特征。
4)实时观察了远端大脑中动脉闭塞模型在缺血和再灌过程中全脑脑血流的动态变化特征。实验发现，在缺血半球的梗塞区域，脑血流在缺血期间下降到基准值的30%左右，然后通过再灌恢复到基准的80%水平。而缺血半球的未梗塞区域在整个实验过程中基本保持在基准的70%-100%范围内。另一方面，未缺血的健侧半球，脑血流在缺血期间上升到基准的110%-120%，然后随着再灌回到基线水平。同时，高分辨率的激光散斑成像技术使我们有可能观察到由于中风缺血引发的侧枝循环的动态变化。因此，对于脑卒中健侧和损伤侧的脑血流在时间和空间上变化的实时监测，不仅有利于脑卒中的血液动力学机制研究，更是相关脑保护研究及临床脑卒中干预治疗手段评价的有力工具之一。
综上所述，激光散斑成像技术的高时空分辨率特征使其在脑血流可视化监测中相较传统技术（如：激光多普勒等）拥有更明显的优势。其设备简单，可进一步结合其他生理参数的监测工具，非常适合神经科学的研究。
First introduced in the1980s, laser speckle contrast imaging (LSCI),based on the coherent scattering properties of moving particles, has been apowerful tool for full-field and real-time imaging of blood flow in vivo.Compared with other conventional methods which measure the blood flowsuffer from low spatial or temporal resolution, or injection of exogenoussubstances, or scanning regional blood flow for full-field imaging, LSCI isnon-contact with high spatio-temporal resolution without scanning. Recently,LSCI has gained increased attention, in part due to its rapid adoption forblood flow studies in the brain under physiological and pathologicalconditions.
In this dissertation, we studied LSCI from three aspects for itsapplication. First, we obtained information on both deoxy-hemoglobinsaturation (based on optical intrinsic signal) and cerebral blood flow (CBF)changes simultaneously from processed LSCI images to study the specifichemodynamic change in response to hypothermia. Second, LSCI was used toinvestigate the functional brain responses to somatosensory stimulation underdifferent conditions, e.g. hypothermia. Third, we studied the real-time changein microcirculation in a rodent model of focal ischemia and post-ischemicreperfusion. In addition, considering the existing problems in LSCI:1)because of the imaging noise and ambient effect in background, the dynamicrange of contrast data is much limited and thus make it difficult to visualizeand analyze the data;2) disturbances due to the breath, heart beating and othernoises decrease the spatial resolution, we successfully dealt with the issuesrespectively according to the methods developed by our lab, i.e. dynamic range enhancement of contrast data based on monotonic point transformationand spatial resolution enhancement by registration method.
The major contributions and conclusions of the thesis are summarized asfollow:
1) Analysis of the influence of blood speed and exposure time on CBFmonitoring. Simulated experiments were carried out to obtain the linearrelationship between contrast of time-varying speckle and real speed. Theresults showed that the optimum speed range was0-5mm/s, which suggestthat the LSCI system was suitable for monitoring the dynamics of CBF.We also considered about the best exposure time for different conditions inblood flow measurement.
2) Influence of hypothermia on CBF and deoxy-hemoglobin change.Hypothermia can happen in daily life accidentally, e.g., in cardiovascularsurgery, or applied as therapeutics in neurosciences critical care unit(NCCU). Clinical induced hypothermia has been demonstrated withneuroprotective effects in patients with traumatic brain injury, stroke andvarious other disorders. It is meaningful to investigate the influences oftemperature change on the CBF. Eighteen male Sprague Dawley rats wereanesthetized with sodium pentobarbital and randomly assigned to mild andmoderate hypothermia groups (n=9each). To study the relative CBFchange and deoxy-hemoglobin saturation in arteriole, venule and capillarylevel under mild (35℃) and moderate (32℃) hypothermia, laser speckleimaging trials were acquired during baseline (37℃), hypothermia (35℃or32℃) and post-rewarming (37℃) phases. By segmentation methodspackaged in Insight Toolkit (ITK) software, the cortical vessels weresegmented to map the CBF. In the mild group, mean CBF in differentvessels all increased throughout the hypothermia and post-rewarmingphases. Deoxy-hemoglobin saturation in veins and capillaries decreasedwithout arteries. On the contrast, mean CBF was reduced by20%at32℃and could return to~90%of the baseline level during post-rewarming inthe moderate group. And the change of deoxy-hemoglobin saturation was not significant at32℃. We would suggest that moderate hypothermia bemore applicable for clinical purpose in the aspect of CBF recovery levelafter the rewarming. But the physiological foundation of CBF change invascular level under hypothermia still need further study.
3) Functional CBF changes under normothermia and hypothermia. LSCI wasused to in the rats with high spatio-temporal resolution. In many studies onfunctional neuroimaging, change in local cerebral blood flow (LCBF)induced by somatosensory stimulation is used as a marker for corticalneuronal activity. Until now, a full description of the relationship betweenthe evoked LCBF and neuronal activity has not been given. In thisexperiment, different activation levels caused by stimulus amplitude(0.5mA,1.5mA and2.5mA) were quantitatively investigated, and were ingood agreement with previous laser Doppler measurements. Electricalstimulation of the hind paw was also carried out with1.5mA pulses (0.3ms pulse width) applied at the frequencies of5Hz for4and8s durations.During the8s stimulation, the evoked LCBF exhibited an initial peakfollowed by a plateau phase. These results suggest that the response ofevoked LCBF reflects the integrated neuronal activity during thestimulation period, and it is modulated by a temporal slow function.Furthermore, we investigated the functional change of CBF, accompaniedwith neuronal activation, during hypothermia. So far thetemperature-induced spatiotemporal responses of neural function have notbeen fully understood. Laser speckle images from Sprague Dawley rats(n=8, male) were acquired under normothermia (37℃) and moderatehypothermia (32℃). For each animal, ten trials of electrical hindpawstimulation (2.5mA,0.3ms,5Hz,4s) were delivered under bothtemperatures. Using registered laser speckle contrast analysis, which wassupposed to eliminate the disturbances from breath and heart beating, andtemporal clustering analysis (TCA), we found a delayed response peak anda prolonged response window under hypothermia. Hypothermia alsodecreased the activation area and the amplitude of the peak CBF. Moreover, capillaries and arterioles are the major contributors in the vascularresponses to functional activation.The results suggest that the combinationof LSCI and TCA is a high resolution functional imaging method toimprove the understanding of the spatiotemporal neurovascular couplingof neuronal activity and hemodynamics under normal and pathematologicbrain function.
4) Real-time monitoring of CBF changes in rodent model of distal middlecerebral artery occlusion during ischemia and post-ischemic reperfusion. Itis shown that the CBF perfusion of the ischemic area at the ischemichemisphere decreased to about30%of the baseline during30min ischemiaand recovered to more than80%after reperfusion. The CBF of thenonischemic area at the ischemic hemisphere sustained from70%to100%of the baseline during the whole phases. On the other hand, the CBF of theintact hemisphere increased to～120%of baseline during the ischemicperiod and recovered to the baseline level after reperfusion. The highspatio-temporal resolution of LSCI also made it possible to map thedynamic changes in stroke-induced collateral blood flow after middlecerebral artery occlusion. Investigation of the spatial and temporaldistribution and hemodynamics of both unaffected and severe ischemiccortex can not only help understand the hemodynamic mechanism ofstroke, but also offer newaspect of the evaluation the effectiveness ofclinical therapy.
In summary, we utilize laser speckle imaging technique to get thespatiotemporal changes in CBF and deoxy-hemoglobin under lowtemperatures and the re-warming, particularly for the clinical mild (35℃) andmoderate (32℃) hypothermia. Furthermore, we investigated the functionalchange in CBF by laser speckle imaging under moderate hypothermia. Andwe were able to monitor the CBF changes of both ischemic and intacthemisphere after dMCAO during ischemia and post-ischemic reperfusion.LSF has distinct advantages over LDF for visualizing CBF changes becauseof its excellent spatiotemporal resolution. This property combined with relatively simple instrumentation has resulted in rapid adoption of LSCI,particularly in neuroscience.
本论文研究内容主要涉及激光散斑成像技术在以下三个方面的应用：首先，我们结合内源光信号特征，通过635纳米激光照射所得的散斑图像同时得到了脱氧血红蛋白浓度和脑血流（CBF）变化的信息，并将之应用于不同亚低温对脑血流影响的研究。其次，将激光散斑成像技术应用于脑功能成像，研究了不同体觉刺激引起的血液动力学响应以及低温对脑功能的影响。最后，利用激光散斑成像的高时空分辨率特性实时动态观测了大鼠局灶性脑缺血模型在缺血和再灌过程中不同脑区脑血流变化的差异。此外，考虑到现有散斑成像技术存在着动态范围较狭窄和受心跳、呼吸等噪声影响使其信噪比降低等问题，我们在图像处理的过程中，引入了基于单调点变化的增强散斑衬比分析方法，拓宽了散斑图像的动态范围，提高了可视化效果，而图像配准的方法也能进一步提高图像的空间分辨率。
本论文主要的研究内容和结论如下所述：
1)通过仿真实验验证了两种散斑衬比分析方法（空间域和时域）所得散斑衬比值和实际流速的绝对值之间在一定范围内线性相关。实验结果显示，在0-5毫米/秒的实际流速范围内，散斑衬比和绝对速度间呈较好的线性关系，说明我们的成像系统非常适合脑血流的动态监测。另外，通过动物实验对系统性能和参数进行了分析，为全文后续研究选取合适的系统参数做了前期的实验证明（如曝光时间的选取等）。
2)研究了不同低温下（35℃和32℃）大鼠脑皮层血流速度和脱氧血红蛋白浓度的相对变化情况。亚低温疗法作为辅助治疗脑损伤（包括脑中风、脑创伤、全局性脑损伤等）的手段已被广泛地应用于重症监护病房（ICU），并被证明具有很好的神经保护作用。而在一些疾病的诊断及脑功能研究中，大脑皮层血流的特征模式是非常重要的参数。因此，若能得到不同低温下，高分辨率的大脑皮层血流变化，将具有一定的科学和临床意义。我们利用时域激光散斑对比度分析和内源光信号来监测大鼠在轻度低温（35℃）和中度低温（32℃）下脑皮层血流以及脱氧血红蛋白浓度的变化，并进一步研究了皮层不同血管内（如：动脉、静脉及毛细血管网）血流变化的规律。18只用戊巴比妥钠麻醉的SD雄性大鼠被随机分成轻度和中度低温实验组（每组9只）。分别在基线期（37℃），低温期（35℃或32℃）和复温后期（37℃）三个阶段记录它们的激光散斑图像，然后用ITK（Insight Toolkit）软件包中的图像分割工具提取不同血管，从而研究动脉、静脉和毛细血管在低温下的流速信息。在轻度低温实验组中，所有脑血管中血流速度在35℃和复温状态下显著增加。静脉和毛细血管中脱氧血红蛋白浓度均下降，但是动脉除外。而在中度低温试验组中，低温阶段所有脑血管内血流比基线值下降20%，并在复温至37℃后能够恢复到大约90%的基线水平。各血管内脱氧血红蛋白浓度在此组中无显著变化。考虑到脑皮层血流复温后的恢复情况，中度低温可能更适合临床应用。当然，关于脑皮层血流在血管水平的生理变化机制以及亚低温的神经保护作用仍有待未来进一步的研究。
3)观察了常温和中度低温下大鼠功能性脑血流变化的时空特征。在众多神经功能成像研究中，均将体觉刺激引起的局部脑血流变化作为研究皮层神经元活动的标志参数之一。但迄今为止，关于诱发的局部脑血流变化和神经元活动间的关系特征尚未被详细描述。从我们的结果可以看到，随着刺激幅值（0.5毫安,1.5毫安和2.5毫安）的上升，脑血流灌注也相应增强，这与文献中用激光多普勒血流计在单点采集得到的实验结果相吻合。我们也对大鼠后肢分别给予了1.5毫安，脉宽0.3毫秒，频率5赫兹的持续时间为4秒和8秒的电刺激。结果发现，在持续8秒电刺激的实验组中，局部脑血流变化在达到峰值后跟随一个平台期。这一系列实验结果表明用激光散斑成像技术观察局部脑血流的响应，可以很好地反映功能神经元组整合的活动特征结果。目前，有关温度对功能响应影响的时空变化特征尚不清楚。我们分别记录了8只雄性SD大鼠在常温（37℃）和中度低温（32℃）下的功能激光散斑图像，以研究亚低温对神经元活动的影响。对每一只实验动物的每一个温度阶段，重复十次相同的后肢电刺激协议（2.5毫安,0.3毫秒脉宽,5赫兹,4秒持续时间），每两组协议间至少休息60秒，对10组结果求平均以消除随机噪声的影响。同时，为减少呼吸和心跳对图像的影响，对所有数据经过配准的激光散斑衬比分析，再结合时间簇分析方法，我们发现低温会引起脑血流功能响应峰值的延迟以及响应持续时间的延长。此外，低温会导致功能活动区域面积减小，脑血流峰值降低。而动脉和毛细血管网相较静脉在功能刺激引起的脑血流响应变化中占据更为主导的地位。以上实验结果表明，结合激光散斑成像技术和时间簇分析方法得到的高时空分辨率功能图像，有助于我们更好地了解神经-血管耦合性在正常或病理状态下的时空特征。
4)实时观察了远端大脑中动脉闭塞模型在缺血和再灌过程中全脑脑血流的动态变化特征。实验发现，在缺血半球的梗塞区域，脑血流在缺血期间下降到基准值的30%左右，然后通过再灌恢复到基准的80%水平。而缺血半球的未梗塞区域在整个实验过程中基本保持在基准的70%-100%范围内。另一方面，未缺血的健侧半球，脑血流在缺血期间上升到基准的110%-120%，然后随着再灌回到基线水平。同时，高分辨率的激光散斑成像技术使我们有可能观察到由于中风缺血引发的侧枝循环的动态变化。因此，对于脑卒中健侧和损伤侧的脑血流在时间和空间上变化的实时监测，不仅有利于脑卒中的血液动力学机制研究，更是相关脑保护研究及临床脑卒中干预治疗手段评价的有力工具之一。
综上所述，激光散斑成像技术的高时空分辨率特征使其在脑血流可视化监测中相较传统技术（如：激光多普勒等）拥有更明显的优势。其设备简单，可进一步结合其他生理参数的监测工具，非常适合神经科学的研究。
First introduced in the1980s, laser speckle contrast imaging (LSCI),based on the coherent scattering properties of moving particles, has been apowerful tool for full-field and real-time imaging of blood flow in vivo.Compared with other conventional methods which measure the blood flowsuffer from low spatial or temporal resolution, or injection of exogenoussubstances, or scanning regional blood flow for full-field imaging, LSCI isnon-contact with high spatio-temporal resolution without scanning. Recently,LSCI has gained increased attention, in part due to its rapid adoption forblood flow studies in the brain under physiological and pathologicalconditions.
In this dissertation, we studied LSCI from three aspects for itsapplication. First, we obtained information on both deoxy-hemoglobinsaturation (based on optical intrinsic signal) and cerebral blood flow (CBF)changes simultaneously from processed LSCI images to study the specifichemodynamic change in response to hypothermia. Second, LSCI was used toinvestigate the functional brain responses to somatosensory stimulation underdifferent conditions, e.g. hypothermia. Third, we studied the real-time changein microcirculation in a rodent model of focal ischemia and post-ischemicreperfusion. In addition, considering the existing problems in LSCI:1)because of the imaging noise and ambient effect in background, the dynamicrange of contrast data is much limited and thus make it difficult to visualizeand analyze the data;2) disturbances due to the breath, heart beating and othernoises decrease the spatial resolution, we successfully dealt with the issuesrespectively according to the methods developed by our lab, i.e. dynamic range enhancement of contrast data based on monotonic point transformationand spatial resolution enhancement by registration method.
The major contributions and conclusions of the thesis are summarized asfollow:
1) Analysis of the influence of blood speed and exposure time on CBFmonitoring. Simulated experiments were carried out to obtain the linearrelationship between contrast of time-varying speckle and real speed. Theresults showed that the optimum speed range was0-5mm/s, which suggestthat the LSCI system was suitable for monitoring the dynamics of CBF.We also considered about the best exposure time for different conditions inblood flow measurement.
2) Influence of hypothermia on CBF and deoxy-hemoglobin change.Hypothermia can happen in daily life accidentally, e.g., in cardiovascularsurgery, or applied as therapeutics in neurosciences critical care unit(NCCU). Clinical induced hypothermia has been demonstrated withneuroprotective effects in patients with traumatic brain injury, stroke andvarious other disorders. It is meaningful to investigate the influences oftemperature change on the CBF. Eighteen male Sprague Dawley rats wereanesthetized with sodium pentobarbital and randomly assigned to mild andmoderate hypothermia groups (n=9each). To study the relative CBFchange and deoxy-hemoglobin saturation in arteriole, venule and capillarylevel under mild (35℃) and moderate (32℃) hypothermia, laser speckleimaging trials were acquired during baseline (37℃), hypothermia (35℃or32℃) and post-rewarming (37℃) phases. By segmentation methodspackaged in Insight Toolkit (ITK) software, the cortical vessels weresegmented to map the CBF. In the mild group, mean CBF in differentvessels all increased throughout the hypothermia and post-rewarmingphases. Deoxy-hemoglobin saturation in veins and capillaries decreasedwithout arteries. On the contrast, mean CBF was reduced by20%at32℃and could return to~90%of the baseline level during post-rewarming inthe moderate group. And the change of deoxy-hemoglobin saturation was not significant at32℃. We would suggest that moderate hypothermia bemore applicable for clinical purpose in the aspect of CBF recovery levelafter the rewarming. But the physiological foundation of CBF change invascular level under hypothermia still need further study.
3) Functional CBF changes under normothermia and hypothermia. LSCI wasused to in the rats with high spatio-temporal resolution. In many studies onfunctional neuroimaging, change in local cerebral blood flow (LCBF)induced by somatosensory stimulation is used as a marker for corticalneuronal activity. Until now, a full description of the relationship betweenthe evoked LCBF and neuronal activity has not been given. In thisexperiment, different activation levels caused by stimulus amplitude(0.5mA,1.5mA and2.5mA) were quantitatively investigated, and were ingood agreement with previous laser Doppler measurements. Electricalstimulation of the hind paw was also carried out with1.5mA pulses (0.3ms pulse width) applied at the frequencies of5Hz for4and8s durations.During the8s stimulation, the evoked LCBF exhibited an initial peakfollowed by a plateau phase. These results suggest that the response ofevoked LCBF reflects the integrated neuronal activity during thestimulation period, and it is modulated by a temporal slow function.Furthermore, we investigated the functional change of CBF, accompaniedwith neuronal activation, during hypothermia. So far thetemperature-induced spatiotemporal responses of neural function have notbeen fully understood. Laser speckle images from Sprague Dawley rats(n=8, male) were acquired under normothermia (37℃) and moderatehypothermia (32℃). For each animal, ten trials of electrical hindpawstimulation (2.5mA,0.3ms,5Hz,4s) were delivered under bothtemperatures. Using registered laser speckle contrast analysis, which wassupposed to eliminate the disturbances from breath and heart beating, andtemporal clustering analysis (TCA), we found a delayed response peak anda prolonged response window under hypothermia. Hypothermia alsodecreased the activation area and the amplitude of the peak CBF. Moreover, capillaries and arterioles are the major contributors in the vascularresponses to functional activation.The results suggest that the combinationof LSCI and TCA is a high resolution functional imaging method toimprove the understanding of the spatiotemporal neurovascular couplingof neuronal activity and hemodynamics under normal and pathematologicbrain function.
4) Real-time monitoring of CBF changes in rodent model of distal middlecerebral artery occlusion during ischemia and post-ischemic reperfusion. Itis shown that the CBF perfusion of the ischemic area at the ischemichemisphere decreased to about30%of the baseline during30min ischemiaand recovered to more than80%after reperfusion. The CBF of thenonischemic area at the ischemic hemisphere sustained from70%to100%of the baseline during the whole phases. On the other hand, the CBF of theintact hemisphere increased to～120%of baseline during the ischemicperiod and recovered to the baseline level after reperfusion. The highspatio-temporal resolution of LSCI also made it possible to map thedynamic changes in stroke-induced collateral blood flow after middlecerebral artery occlusion. Investigation of the spatial and temporaldistribution and hemodynamics of both unaffected and severe ischemiccortex can not only help understand the hemodynamic mechanism ofstroke, but also offer newaspect of the evaluation the effectiveness ofclinical therapy.
In summary, we utilize laser speckle imaging technique to get thespatiotemporal changes in CBF and deoxy-hemoglobin under lowtemperatures and the re-warming, particularly for the clinical mild (35℃) andmoderate (32℃) hypothermia. Furthermore, we investigated the functionalchange in CBF by laser speckle imaging under moderate hypothermia. Andwe were able to monitor the CBF changes of both ischemic and intacthemisphere after dMCAO during ischemia and post-ischemic reperfusion.LSF has distinct advantages over LDF for visualizing CBF changes becauseof its excellent spatiotemporal resolution. This property combined with relatively simple instrumentation has resulted in rapid adoption of LSCI,particularly in neuroscience.
引文
[1] L. Edvinson, et al.,"Cerebral blood flow and metabolism," Alzheimer Disease&AssociatedDisorders, vol.7, p.129,1993.
[2]田牛,微循环方法学:原子能出版社,1993.
[3] WHO.(2008). The Top Ten Causes of Death. Available:http://www.who.int/mediacentre/factsheets/fs310_2008.pdf
[4]赵克森, et al.,微循环与健康.科学出版社;1999.
[5] J. H. SIEGEL,"The effect of associated injuries, blood loss, and oxygen debt on death and disabilityin blunt traumatic brain injury: the need for early physiologic predictors of severity," Journal ofneurotrauma, vol.12, pp.579-590,1995.
[6] A. P. Shepherd and P. berg, Laser-Doppler blood flowmetry: Springer Netherlands,1990.
[7] J. D. Briers, et al.,"Capillary Blood Flow Monitoring Using Laser Speckle Contrast Analysis(LASCA)," Journal of Biomedical Optics, vol.4, p.164,1999.
[8] J. D. Briers and A. F. Fercher,"Retinal blood-flow visualization by means of laser specklephotography," Investigative Ophthalmology&Visual Science, vol.22, pp.255-9, Feb1982.
[9] J. D. Briers,"Laser Doppler, speckle and related techniques for blood perfusion mapping andimaging," Physiological Measurement, vol.22,2001.
[10] A. Dunn, et al.,"Dynamic imaging of cerebral blood flow using laser speckle," Journal of CerebralBlood Flow&Metabolism, vol.21, pp.195-201,2001.
[11] B. Ruth,"Measuring the steady-state value and the dynamics of the skin blood flow using thenon-contact laser speckle method," Medical Engineering&Physics, vol.16, pp.105-11,1994.
[12] Y. Tamaki, et al.,"Noncontact, two-dimensional measurement of retinal microcirculation using laserspeckle phenomenon," Investigative Ophthalmology&Visual Science, vol.35, pp.3825-3834,1994.
[13] K. Yaoeda, et al.,"Measurement of microcirculation in the optic nerve head by laser speckleflowgraphy and scanning laser Doppler flowmetry," American Journal of Ophthalmology, vol.129,pp.734-9, Jun2000.
[14] H. Cheng, et al.,"Laser speckle imaging of blood flow in microcirculation," Physics in MedicineAnd Biology, vol.49, pp.1347-57,2004.
[15]程海英, et al.,"对药物作用下大鼠肠系膜上区域性血流变化的实时动态光学监测,"自然科学进展, vol.13, pp.198-201,2003.
[16] C. Zhou, et al.,"Acute functional recovery of cerebral blood flow after forebrain ischemia in rat,"Journal of Cerebral Blood Flow&Metabolism, vol.28, pp.1275-84,2008.
[17] S. K. Nadkarni, et al.,"Characterization of atherosclerotic plaques by laser speckle imaging,"Circulation, vol.112, p.885,2005.
[18] D. Zhu, et al.,"Monitoring thermal-induced changes in tumor blood flow and microvessels withlaser speckle contrast imaging," Applied Optics, vol.46, pp.1911-7,2007.
[19] W. Lau, et al.,"Spatiotemporal characteristics of low-frequency functional activation measured bylaser speckle imaging," IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol.13, pp.179-85,2005.
[20] N. Li, et al.,"High spatiotemporal resolution imaging of the neurovascular response to electricalstimulation of rat peripheral trigeminal nerve as revealed by in vivo temporal laser speckle contrast,"Journal of neuroscience methods, vol.176, pp.230-6,2009.
[21] D. A. Boas and A. K. Dunn,"Laser speckle contrast imaging in biomedical optics," Journal ofBiomedical Optics, vol.15, p.011109,2010.
[22] J. C. Dainty,"Laser speckle and related phenomena," Berlin and New York, Springer-Verlag,1975.
[23] J. Briers,"Wavelength dependence of intensity fluctuations in laser speckle patterns from biologicalspecimens," Optics Communications, vol.13, pp.324-6,1975.
[24] M. D. Stern,"In vivo evaluation of microcirculation by coherent light scattering," Nature, vol.254,pp.56-8,1975.
[25] A. F. Fercher and J. D. Briers,"Flow visualization by means of single-exposure specklephotography," Optics Communications, vol.37, pp.326-30,1981.
[26] S. Ul'yanov, et al.,"The application of speckle interferometry for the monitoring of blood andlymph flow in microvessels," Lasers in Medical Science, vol.12, pp.31-41,1997.
[27] J. S. Paul, et al.,"Imaging the development of an ischemic core following photochemically inducedcortical infarction in rats using Laser Speckle Contrast Analysis (LASCA)," NeuroImage, vol.29,pp.38-45,2006.
[28] P. Miao, et al.,"High Resolution Cerebral Blood Flow Imaging by Registered Laser SpeckleContrast Analysis," IEEE Transactions on Biomedical Engineering, vol.57, pp.1152-7,2010.
[29] Z. Wang, et al.,"Peri-infarct temporal changes in intrinsic optical signal during spreadingdepression in focal ischemic rat cortex," Neuroscience letters, vol.424, pp.133-8,2007.
[30] Q. Liu, et al.,"Laser speckle contrast imaging: monitoring blood flow dynamics and vascularstructure of photodynamic therapy," Proceedings of SPIE, vol.5630, p.26,2005.
[31] T. Durduran, et al.,"Spatiotemporal quantification of cerebral blood flow during functionalactivation in rat somatosensory cortex using laser-speckle flowmetry," Journal of Cerebral BloodFlow&Metabolism, vol.24, pp.518-25,2004.
[32] H. Z. Cummins, Photon correlation spectroscopy and velocimetry: Plenum Pub Corp,1977.
[33] H. Fujii, et al.,"Blood flow observed by time-varying laser speckle," Optics letters, vol.10, pp.104-6,1985.
[34] H. Fujii, et al.,"Evaluation of blood flow by laser speckle image sensing. Part1," Applied Optics,vol.26, pp.5321-5,1987.
[35] B. Ruth,"Non-contact blood flow determination using a laser speckle method," Optics&LaserTechnology, vol.20, pp.309-16,1988.
[36] J. D. Briers and S. Webster,"Laser Speckle Contrast Analysis (LASCA): A Nonscanning, Full-FieldTechnique for Monitoring Capillary Blood Flow," Journal of Biomedical Optics, vol.1, pp.174,1996.
[37] C. M. Waterman-Storer, et al.,"Fluorescent speckle microscopy, a method to visualize the dynamicsof protein assemblies in living cells," Current biology, vol.8, pp.1227-30,1998.
[38] R. Bandyopadhyay, et al.,"Speckle-visibility spectroscopy: A tool to study time-varying dynamics,"Review of Scientific Instruments, vol.76, pp.093110,2005.
[39] S. Kirkpatrick, et al.,"Detrimental effects of speckle-pixel size matching in laser speckle contrastimaging," Optics letters, vol.33, pp.2886-8,2008.
[40] D. Duncan, et al.,"Statistics of local speckle contrast," Journal of the Optical Society of America A,vol.25, pp.9-15,2008.
[41] W. J. Tom, et al.,"Efficient processing of laser speckle contrast images," IEEE Transactions onMedical Imaging, vol.27, pp.1728-38,2008.
[42] S. Liu, et al.,"Fast blood flow visualization of high-resolution laser speckle imaging data usinggraphics processing unit," Optics Express, vol.16, pp.14321-9,2008.
[43] W. Tom, et al.,"Efficient processing of laser speckle contrast images," IEEE Transactions onMedical Imaging, vol.27, pp.1728-38,2008.
[44] A. B. Parthasarathy, et al.,"Robust flow measurement with multi-exposure speckle imaging,"Optics Express, vol.16, pp.1975-89,2008.
[45] P. Miao, et al.,"Random process estimator for laser speckle imaging of cerebral blood flow," OpticsExpress, vol.18, pp.218-36,2010.
[46] P. Miao, et al.,"Imaging the Cerebral Blood Flow With Enhanced Laser Speckle Contrast Analysis(eLASCA) by Monotonic Point Transformation," IEEE Transactions on Biomedical Engineering,vol.56, pp.1127-33,2009.
[47] P. Miao, et al.,"Detecting Cerebral Arteries and Veins: from Large to Small," Journal of InnovativeOptical Health Sciences, vol.3, pp.61-7,2010.
[48] N. Hecht, et al.,"Intraoperative monitoring of cerebral blood flow by laser speckle contrastanalysis," Neurosurgical Focus, vol.27, p. E11,2009.
[49] P. G. McGuire and T. R. Howdieshell,"The Importance of Engraftment in Flap Revascularization:Confirmation by Laser Speckle Perfusion Imaging," Journal of Surgical Research,2010.
[50] M. Roustit, et al.,"Excellent reproducibility of laser speckle contrast imaging to assess skinmicrovascular reactivity," Microvascular Research, vol80, pp.505-11,2010.
[51] G. Mahe, et al.,"Laser speckle contrast imaging accurately measures blood flow over moving skinsurfaces," Microvascular Research, pp.183-8,2010.
[52] C. M. Treu, et al.,"Sidestream dark field imaging: the evolution of real-time visualization ofcutaneous microcirculation and its potential application in dermatology," Archives ofDermatological Research, pp.1-10,2011.
[53] J. D. Briers,"Laser speckle contrast imaging for measuring blood flow," Optica Applicata, vol.37, p.139,2007.
[54]骆清铭, et al.,"脑功能光学成像,"首届全国功能神经影像学和神经信息学研讨会论文汇编,2003.
[55] A. Villringer and B. Chance,"Non-invasive optical spectroscopy and imaging of human brainfunction," Trends in neurosciences, vol.20, pp.435-42,1997.
[56] Available: http://www-sop.inria.fr/members/Maureen.Clerc/functionalimagingbrain.php
[57] C. Roy and C. Sherrington,"On the regulation of the blood-supply of the brain," The Journal ofphysiology, vol.11, p.85,1890.
[58] A. Villringer and U. Dirnagl,"Coupling of brain activity and cerebral blood flow: basis of functionalneuroimaging," Cerebrovascular and Brain Metabolism Reviews, vol.7, p.240,1995.
[59] D. Heeger and D. Ress,"What does fMRI tell us about neuronal activity?" Nature ReviewsNeuroscience, vol.3, pp.142-51,2002.
[60] K. H. Polderman,"Application of therapeutic hypothermia in the ICU: opportunities and pitfalls of apromising treatment modality. Part1: Indications and evidence," Intensive Care Medicine, vol.30,pp.556-75,2004.
[61] K. C. Wong,"Physiology and pharmacology of hypothermia," Western Journal of Medicine, vol.138, pp.227-32,1983.
[62] L. W. Smith and T. Fay,"Observations on human beings with cancer maintained at reducedtemperature of75-90Fahrenheit (24-32C)," American Journal of Clinical Pathology, vol.10, pp.1-11,1940.
[63] T. Fay,"Observations on generalized refrigeration in cases of severe cerebral trauma," Assoc ResNerv Ment Dis Proc, vol.24, pp.611-9,1943.
[64] J. H. Talbott,"The physiologic and therapeutic effects of hypothermia," New England Journal ofMedicine, vol.224, pp.281-8,1941.
[65] W. G. Bigelow, et al.,"Hypothermia; its possible role in cardiac surgery: an investigation of factorsgoverning survival in dogs at low body temperatures," Annals of Surgery, vol.132, pp.849-66,1950.
[66] H. L. Rosomoff and P. Safar,"Management of the comatose patient," Clinical Anesthesia, vol.1, pp.244-58,1965.
[67] R. Busto, et al.,"Small differences in intraischemic brain temperature critically determine the extentof ischemic neuronal injury," Journal of Cerebral Blood Flow&Metabolism, vol.7, pp.729-38,Dec1987.
[68] G. L. Clifton, et al.,"Lack of Effect of Induction of Hypothermia after Acute Brain Injury," NewEngland Journal of Medicine, vol.344, p.556,2001.
[69] G. L. Clifton, et al.,"Marked protection by moderate hypothermia after experimental traumatic braininjury," Journal of Cerebral Blood Flow&Metabolism, vol.11, pp.114-21,1991.
[70]李承晏and刘传玉,"亚低温联合升压治疗对局灶性脑缺血的脑保护作用,"中国危重病急救医学, vol.14, pp.684-5,2002.
[71]许鹏程and陈群,"亚低温对脑缺血后延迟性神经元坏死的影响,"徐州医学院学报, vol.18, pp.455-7,1998.
[72]朱长连, et al.,"低温对新生大鼠缺氧缺血性脑损伤的保护作用及其机制,"中华儿科杂志, vol.41, pp.911-5,2003.
[73]刘登礼, et al.,"振幅整合脑电图在新生儿缺氧缺血性脑病诊断中的应用价值,"临床儿科杂志,vol.23, pp.324-5,2005.
[74]邵肖梅,"新生儿缺氧缺血性脑病的亚低温治疗,"中国实用儿科杂志, vol.21, pp.647-50,2006.
[75]汪吉梅,"选择性头部亚低温治疗新生猪缺氧缺血性脑损伤脑电生理的变化,"2005.
[76]汪吉梅, et al.,"亚低温对新生猪缺氧缺血脑损伤振幅整合脑电图变化的影响,"中国当代儿科杂志, vol.7, pp.159-62,2005.
[77] P. D. Lyden, et al.,"Therapeutic hypothermia for acute stroke," International Journal of Stroke, vol.1, pp.9-19,2006.
[78] N. C. Care,"Induced hypothermia in critical care medicine: A review," Critical Care Medicine, vol.31, p.2041,2003.
[79] T. M. Hemmen and P. D. Lyden,"Induced hypothermia for acute stroke," Stroke, vol.38, p.794,2007.
[80] S. A. Bernard, et al.,"Treatment of comatose survivors of out-of-hospital cardiac arrest withinduced hypothermia," New England Journal of Medicine, vol.346, pp.557-63,2002.
[81] P. J. Safar and P. M. Kochaned,"Mild therapeutic hypothermia to improve the neurologic outcomeafter cardiac arrest," New England Journal of Medicine, vol.346, pp.612-3,2002.
[82] D. L. Taylor, et al.,"Improved neuroprotection with hypothermia delayed by6hours followingcerebral hypoxia-ischemia in the14-day-old rat," Pediatric Research, vol.51, pp.13-9,2002.
[83] J. P. Nolan, et al.,"Therapeutic hypothermia after cardiac arrest. An advisory statement by theAdvancement Life support Task Force of the International Liaison committee on Resuscitation,"Resuscitation, vol.57, pp.231-5,2003.
[84] K. Niwa, et al.,"Mild hypothermia disturbs regional cerebrovascular autoregulation in awake rats,"Brain Research, vol.789, pp.68-73,1998.
[85] W. E. Hoffman and C. Thomas,"Effects of graded hypothermia on outcome from brain ischemia,"Neurological Research, vol.18, pp.185-9,1996.
[86] J. W. Kuluz, et al.,"Selective brain cooling increases cortical cerebral blood flow in rats," AmericanJournal of Physiology-Heart and Circulatory Physiology, vol.265, pp.824-7,1993.
[87] W. Wang, et al.,"A preliminary study on determining the time window of hypothermia cerebralprotection in rat cortex by laser speckle flowmetry," Proceedings of SPIE, vol.6445, p.64450Q,2007.
[88] L. I. Goldfischer,"Autocorrelation function and power spectral density of laser-produced specklepatterns," Journal of the Optical Society of America, vol.55, pp.247-53,1965.
[89] J. D. Briers,"Holographic, speckle and moiré techniques in optical metrology," Progress inQuantum Electronics, vol.17, pp.167-233,1993.
[90] A. K. Dunn, et al.,"Simultaneous imaging of total cerebral hemoglobin concentration, oxygenation,and blood flow during functional activation," Optics letters, vol.28, pp.28-30,2003.
[91] H. Cheng, et al.,"Modified laser speckle imaging method with improved spatial resolution,"Journal of Biomedical Optics, vol.8, pp.559-64,2003.
[92] J. D. Rigden and E. I. Gordon,"The granularity of scattered optical maser light," Proc. IRE, vol.50,pp.2367-8,1962.
[93] J. W. Goodman, et al.,"Laser Speckle and Related Phenomena," Statistical Properties of LaserSpeckle Patterns, vol.9, pp.9-75,1975.
[94] A. Serov, et al.,"Speckles in laser Doppler blood flowmetry," Proceedings of SPIE, vol.4242, p.306,2001.
[95] J. Ohtsubo and T. Asakura,"Velocity measurement of a diffuse object by using time-varyingspeckles," Optical and Quantum Electronics, vol.8, pp.523-9,1976.
[96] J. D. Briers,"A note on the statistics of laser speckle patterns added to coherent and incoherentuniform background fields, and a possible application for the case of incoherent addition," Opticaland Quantum Electronics, vol.7, pp.422-4,1975.
[97] H. Z. Cummins and E. R. Pike, Photon correlation spectroscopy and velocimetry: Plenum,1977.
[98] J. D. Briers,"Time-varying laser speckle for measuring motion and flow," Proceedings of SPIE, vol.4242, p.25,2003.
[99] J. W. Goodman,"Some fundamental properties of speckle," Journal of the Optical Society ofAmerica, vol.66, pp.1145-50,1976.
[100] T. S. McKechnie,"Speckle reduction," Laser Speckle and Related Phenomena, pp.123-70,1984.
[101] V. Tuchin, Handbook of optical biomedical diagnostics: Society of Photo Optical,2002.
[102] J. W. Goodman,"Some effects of target-induced scintillation on optical radar performance,"Proceedings of the IEEE, vol.53, pp.1688-700,1965.
[103] B. Berne and R. Pecora, Dynamic light scattering: Wiley New York,1976.
[104] J. W. Goodman,"Some fundamental properties of speckle," Journal of the Optical Society ofAmerica, vol.66, pp.1145-50,1976.
[105] R. Bonner and R. Nossal,"Model for laser Doppler measurements of blood flow in tissue," AppliedOptics, vol.20, pp.2097–107,1981.
[106] M. Draijer, et al.,"Review of laser speckle contrast techniques for visualizing tissue perfusion,"Lasers in Medical Science, vol.24, pp.639-51,2009.
[107] G. Vargas, et al.,"Morphological Changes in Blood Vessels Produced by Hyperosmotic Agents andMeasured by Optical Coherence Tomography," Photochemistry and photobiology, vol.77, pp.541-9,2003.
[108] R. Jain and L. Munn,"Dissecting tumour pathophysiology using intravital microscopy," NatureReviews Cancer, vol.2, pp.266-76,2002.
[109] S. Yuan, et al.,"Determination of optimal exposure time for imaging of blood flow changes withlaser speckle contrast imaging," Applied Optics, vol.44, pp.1823-30, Apr12005.
[110] V. Tuchin,"Optical clearing of tissues and blood using the immersion method," Journal of PhysicsD: Applied Physics, vol.38, p.2497,2005.
[111] A. Takasu, et al.,"Mild or moderate hypothermia, but not increased oxygen breathing, increaseslong-term survival after uncontrolled hemorrhagic shock in rats," Critical care medicine, vol.28, pp.2465-74,2000.
[112] S. H. Kim, et al.,"Hypothermia and minimal fluid resuscitation increase survival after uncontrolledhemorrhagic shock in rats," Journal Of Trauma-injury Infection And Critical Care, vol.42, pp.213-22,1997.
[113] L. Ibanez, et al.,"The ITK Software Guide."
[114] N. Otsu,"A threshold selection method from gray-level histograms," IEEE Transactions on Systems,Man, and Cybernetics, vol.9, pp.62-6,1979.
[115]付忠良,"图像阈值选取方法: Otsu方法的推广,"计算机应用, vol.20, pp.37-9,2000.
[116] M. Nemoto, et al.,"Analysis of optical signals evoked by peripheral nerve stimulation in ratsomatosensory cortex: dynamic changes in hemoglobin concentration and oxygenation," Journal ofCerebral Blood Flow&Metabolism, vol.19, pp.246-59,1999.
[117] B. G. Covino and A. H. Hegnauer,"Electrolytes and pH Changes in Relation to HypothermicVentricular Fibrillation," Circulation Research, vol.3, pp.575-80,1955.
[118] J. Biem, et al.,"Out of the cold: management of hypothermia and frostbite," Canadian MedicalAssociation Journal, vol.168, pp.305-11,2003.
[119] B. Walter, et al.,"Coupling of Cerebral Blood Flow and Oxygen Metabolism in Infant Pigs DuringSelective Brain Hypothermia," Journal of Cerebral Blood Flow&Metabolism, vol.20, pp.1215-24,2000.
[120] T. Hishinuma, et al.,"III.1. Changes of Brain Distribution of [11C] methamphetamine byPentobarbital Anesthesia in Mice." CYRIC Annual Report, pp.79-82,2002.
[121] L. Edvinsson, et al., Cerebral blood flow and metabolism vol.27: Lippincott Williams&WilkinsPhiladelphia, PA,2002.
[122] K. S. Hendrich, et al.,"Cerebral perfusion during anesthesia with fentanyl, isoflurane, orpentobarbital in normal rats studied by arterial spin-labeled MRI," Magnetic Resonance in Medicine,vol.46, pp.202-6,2001.
[123] H. C. Wartenberg, et al.,"Pharmacological modification of sodium channels from the human heartatrium in planar lipid bilayers: electrophysiological characterization of responses to batrachotoxinand pentobarbital," European Journal of Anaesthesiology, vol.20, pp.354-62,2005.
[124] R. A. Henker, et al.,"Comparison of brain temperature with bladder and rectal temperatures inadults with severe head injury," Neurosurgery, vol.42, pp.1071-5,1998.
[125] A. Ngai, et al.,"Simultaneous measurements of pial arteriolar diameter and laser-Doppler flowduring somatosensory stimulation," Journal of cerebral blood flow and metabolism: official journalof the International Society of Cerebral Blood Flow and Metabolism, vol.15, p.124,1995.
[126] J. Detre, et al.,"Signal averaged laser Doppler measurements of activation-flow coupling in the ratforepaw somatosensory cortex," Brain Research, vol.796, pp.91-8,1998.
[127] T. Woolsey, et al.,"Neuronal units linked to microvascular modules in cerebral cortex: responseelements for imaging the brain," Cerebral Cortex, vol.6, p.647,1996.
[128] A. Silva, et al.,"Simultaneous blood oxygenation level-dependent and cerebral blood flowfunctional magnetic resonance imaging during forepaw stimulation in the rat," Journal of CerebralBlood Flow&Metabolism, vol.19, pp.871-9,1999.
[129] L. Pelosi, et al.,"The effect of stimulus frequency on spinal and scalp somatosensory evokedpotentials to stimulation of nerves in the lower limb," Electroencephalography and clinicalneurophysiology. Supplement, vol.41, p.149,1990.
[130] T. Matsuura, et al.,"CBF change evoked by somatosensory activation measured by laser-Dopplerflowmetry: independent evaluation of RBC velocity and RBC concentration," The Japanese Journalof Physiology, vol.49, pp.289-96,1999.
[131] F. Hyder, et al.,"Dynamic magnetic resonance imaging of the rat brain during forepaw stimulation,"Journal of cerebral blood flow and metabolism: official journal of the International Society ofCerebral Blood Flow and Metabolism, vol.14, p.649,1994.
[132] S. Keilholz, et al.,"Functional MRI of the rodent somatosensory pathway using multislice echoplanar imaging," Magnetic Resonance in Medicine, vol.52, pp.89-99,2004.
[133] N. Camp, et al.,"Stimulation of the rat somatosensory cortex at different frequencies and pulsewidths," NMR in Biomedicine, vol.19, pp.10-7,2006.
[134] S. Narayan,"Functional increases in cerebral blood volume over somatosensory cortex," Journal ofCerebral Blood Flow&Metabolism, vol.15, pp.754-65,1995.
[135] P. Fox and M. Raichle,"Focal physiological uncoupling of cerebral blood flow and oxidativemetabolism during somatosensory stimulation in human subjects," Proceedings of the NationalAcademy of Sciences of the United States of America, vol.83, p.1140,1986.
[136] M. Jones, et al.,"Concurrent optical imaging spectroscopy and laser-Doppler flowmetry: therelationship between blood flow, oxygenation, and volume in rodent barrel cortex," NeuroImage, vol.13, pp.1002-15,2001.
[137] J. Mayhew, et al.,"Increased oxygen consumption following activation of brain: theoreticalfootnotes using spectroscopic data from barrel cortex," NeuroImage, vol.13, pp.975-87,2001.
[138] S. A. Sheth, et al.,"Linear and nonlinear relationships between neuronal activity, oxygenmetabolism, and hemodynamic responses," Neuron, vol.42, pp.347-55,2004.
[139] J. Wall and C. Cusick,"Cutaneous responsiveness in primary somatosensory (SI) hindpaw cortexbefore and after partial hindpaw deafferentation in adult rats," Journal of Neuroscience, vol.4, p.1499,1984.
[140] J. Snyman, Practical mathematical optimization: an introduction to basic optimization theory andclassical and new gradient-based algorithms, Springer Verlag,2005.
[141] C. H. Chen-Bee, et al.,"Areal extent quantification of functional representations using intrinsicsignal optical imaging," Journal of Neuroscience Methods, vol.68, pp.27-37,1996.
[142] J. Martindale, et al.,"The hemodynamic impulse response to a single neural event," Journal ofCerebral Blood Flow&Metabolism, vol.23, pp.546-55, May2003.
[143] B. Ances, et al.,"Coupling of neural activation to blood flow in the somatosensory cortex of rats istime-intensity separable, but not linear," Journal of Cerebral Blood Flow&Metabolism, vol.20, pp.921-30,2000.
[144] T. Matsuura and I. Kanno,"Quantitative and temporal relationship between local cerebral bloodflow and neuronal activation induced by somatosensory stimulation in rats," Neuroscience Research,vol.40, pp.281-90,2001.
[145] W. Grill Jr and J. Mortimer,"The effect of stimulus pulse duration on selectivity of neuralstimulation," IEEE Transactions on Biomedical Engineering, vol.43, pp.161-6,2002.
[146] A. Dunn, et al.,"Spatial extent of oxygen metabolism and hemodynamic changes during functionalactivation of the rat somatosensory cortex," NeuroImage, vol.27, pp.279-90,2005.
[147] A. Devor, et al.,"Coupling of total hemoglobin concentration, oxygenation, and neural activity inrat somatosensory cortex," Neuron, vol.39, pp.353-9,2003.
[148] S. Sheth, et al.,"Columnar specificity of microvascular oxygenation and volume responses:implications for functional brain mapping," Journal of Neuroscience, vol.24, p.634,2004.
[149] S. A. Bernard and M. Buist,"Induced hypothermia in critical care medicine: a review," Critical CareMedicine, vol.31, pp.2041-51,2003.
[150] K. R. Diller and L. Zhu,"Hypothermia therapy for brain injury," Annual Review of BiomedicalEngineering, vol.11, pp.135-62,2009.
[151] P. Bath,"Re: Stroke Therapy Academic Industry Roundtable II (STAIR-II)," Stroke, vol.33, pp.639-40,2002.
[152] V. E. O'Collins, et al.,"Experimental treatments in acute stroke," Annals of Neurology, vol.59, pp.467-77,2006.
[153] M. Erecinska, et al.,"Effects of hypothermia on energy metabolism in mammalian central nervoussystem," Journal of Cerebral Blood Flow&Metabolism, vol.23, pp.513-30,2003.
[154] K. Nakashima and M. M. Todd,"Effects of hypothermia on the rate of excitatory amino acid releaseafter ischemic depolarization," Stroke, vol.27, pp.913-8,1996.
[155] R. Busto, et al.,"Effect of mild hypothermia on ischemia-induced release of neurotransmitters andfree fatty acids in rat brain," Stroke, vol.20, pp.904-10,1989.
[156] J. S. Beckman and W. H. Koppenol,"Nitric oxide, superoxide, and peroxynitrite: the good, the bad,and ugly," American Journal of Physiology: Cell Physiology, vol.271, pp. C1424-37,1996.
[157] C. Iadecola,"Regulation of the cerebral microcirculation during neural activity: is nitric oxide themissing link?" Trends in Neurosciences, vol.16, pp.206-14,1993.
[158] Y. Liu, et al.,"The temporal response of the brain after eating revealed by functional MRI," Nature,vol.405, pp.1058-62,2000.
[159] N. Ramsey, et al.,"Functional MRI experiments: acquisition, analysis and interpretation of data,"European Neuropsychopharmacology, vol.12, pp.517-26,2002.
[160] R. Baumgartner, et al.,"Resampling as a cluster validation technique in fMRI," Journal of MagneticResonance Imaging, vol.11, pp.228-31,2000.
[161] Y. Shu, et al.,"Turning on and off recurrent balanced cortical activity," Nature, vol.423, pp.288-93,2003.
[162] E. Hillman, et al.,"Depth-resolved optical imaging and microscopy of vascular compartmentdynamics during somatosensory stimulation," NeuroImage, vol.35, pp.89-104,2007.
[163] J. C. Rajapakse, et al.,"Modeling hemodynamic response for analysis of functional MRItime-series," Human Brain Mapping, vol.6, pp.283-300,1998.
[164] M. Svensen, et al.,"Probabilistic modeling of single-trial fMRI data," IEEE Transactions onMedical Imaging, vol.19, pp.25-35,2002.
[165] R. D. Dripps and R. W. Virtue,"The Physiology of Induced Hypothermia. Proceedings of aSymposium," Anesthesiology, vol.19, p.118,1958.
[166] E. A. Kiyatkin,"Brain hyperthermia as physiological and pathological phenomena," Brain ResearchReviews, vol.50, pp.27-56,2005.
[167] G. Royl, et al.,"Hypothermia effects on neurovascular coupling and cerebral metabolic rate ofoxygen," NeuroImage, vol.40, pp.1523-32,2008.
[168] T. Deboer and I. Tobler,"Temperature dependence of EEG frequencies during natural hypothermia,"Brain research, vol.670, pp.153-6,1995.
[169] X. H. Zhu, et al.,"Noninvasive and three-dimensional imaging of CMRO2in rats at9.4T:reproducibility test and normothermia/hypothermia comparison study," Journal of Cerebral BloodFlow&Metabolism, vol.27, pp.1225-34,2006.
[170] P. Krafft, et al.,"Mild and Moderate Hypothermia ({alpha}-Stat) Do Not Impair the CouplingBetween Local Cerebral Blood Flow and Metabolism in Rats Editorial Comment," Stroke, vol.31,pp.1393-400,2000.
[171] R. Duelli and W. Kuschinsky,"Changes in brain capillary diameter during hypocapnia andhypercapnia," Journal of Cerebral Blood Flow&Metabolism, vol.13, pp.1025-8,1993.
[172] C. Iadecola, et al.,"Local and propagated vascular responses evoked by focal synaptic activity incerebellar cortex," Journal of Neurophysiology, vol.78, pp.651-9,1997.
[173] A. Villringer, et al.,"Capillary perfusion of the rat brain cortex. An in vivo confocal microscopystudy," Circulation Research, vol.75, pp.55-62,1994.
[174] A. Gjedde and M. Rasmussen,"Blood-brain glucose transport in the conscious rat: comparison ofthe intravenous and intracarotid injection methods," Journal of Neurochemistry, vol.35, pp.1375-81,1980.
[175] M. Ueki, et al.,"Effect of alpha-chloralose, halothane, pentobarbital and nitrous oxide anesthesia onmetabolic coupling in somatosensory cortex of rat," Acta Anaesthesiologica Scandinavica, vol.36,pp.318-22,1992.
[176] S. Nagahiro, et al.,"Pathophysiology and treatment of cerebral ischemia," The Journal of MedicalInvestigation, vol.45, p.57,1998.
[177] H. Kato, et al.,"Temporal profile of the effects of pretreatment with brief cerebral ischemia on theneuronal damage following secondary ischemic insult in the gerbil: cumulative damage andprotective effects," Brain Research, vol.553, pp.238-42,1991.
[178] K. Overgaard, et al.,"A rat model of reproducible cerebral infarction using thrombotic blood clotemboli," Journal of Cerebral Blood Flow&Metabolism, vol.12, pp.484-90,1992.
[179] J. Koizumi, et al.,"Experimental studies of ischemic brain edema, I: a new experimental model ofcerebral embolism in rats in which recirculation can be introduced in the ischemic area," JapaneseJournal of Stroke, vol.8, pp.1-8,1986.
[180] K. A. Hossmann,"Reperfusion of the brain after global ischemia: hemodynamic disturbances,"Shock, vol.8, p.95,1997.
[181] A. Green,"Pharmacological approaches to acute ischaemic stroke: reperfusion certainly,neuroprotection possibly," British journal of pharmacology, vol.153, pp. S325-38,2008.
[182] D. S. Liebeskind,"Collateral circulation," Stroke, vol.34, p.2279,2003.
[183] D. S. Liebeskind,"Collaterals in acute stroke: beyond the clot," Neuroimaging Clinics of NorthAmerica, vol.15, pp.553-73,2005.
[184] W. K. Pratt,"Digital image processing: PIKS inside,"2001.
[185] D. R. Cox and D. Oakes, Analysis of survival data. Chapman&Hall/CRC,1984.
[186] K. Zuiderveld,"Contrast limited adaptive histogram equalization," pp.474-85,1994.
[187] H. K. Shin, et al.,"Mild induced hypertension improves blood flow and oxygen metabolism intransient focal cerebral ischemia," Stroke, vol.39, p.1548,2008.
[188]O. Y. Bang, et al.,"Impact of collateral flow on tissue fate in acute ischaemic stroke," Journal of Neurology, Neurosurgery&Psychiatry, vol.79, p.625,2008.
[189]王拥军.统计显示中风正向中青年入侵.北京科技报,2009.Available：http://tech.sina.com.cn/d/2009-01-05/14472718512.shtml
[190]张微微,”重新认识短暂性脑缺血发作,”中华老年心脑血管病杂志,vol.4,pp.75-7,2002.
[191]B. Schmitz, et al.,"Recovery of the rodent brain after cardiac arrest:A functional MRI study," Magnetic resonance in medicine, vol.39, pp.783-8,1998.
[192]B. M. Ances, et al.,"Acute carotid occlusion alters the activation flow coupling response to forepaw stimulation in a rat model. Editorial comment," Stroke, vol.31, pp.955-60,2000.
[193]R. M. Dijkhuizen, et al.,"Correlation between Brain Reorganization, Ischemic Damage, and Neurologic Status after Transient Focal Cerebral Ischemia in Rats:A Functional Magnetic Resonance Imaging Study," Journal of Neuroscience, vol.23, p.510,2003.
[2]田牛,微循环方法学:原子能出版社,1993.
[3] WHO.(2008). The Top Ten Causes of Death. Available:http://www.who.int/mediacentre/factsheets/fs310_2008.pdf
[4]赵克森, et al.,微循环与健康.科学出版社;1999.
[5] J. H. SIEGEL,"The effect of associated injuries, blood loss, and oxygen debt on death and disabilityin blunt traumatic brain injury: the need for early physiologic predictors of severity," Journal ofneurotrauma, vol.12, pp.579-590,1995.
[6] A. P. Shepherd and P. berg, Laser-Doppler blood flowmetry: Springer Netherlands,1990.
[7] J. D. Briers, et al.,"Capillary Blood Flow Monitoring Using Laser Speckle Contrast Analysis(LASCA)," Journal of Biomedical Optics, vol.4, p.164,1999.
[8] J. D. Briers and A. F. Fercher,"Retinal blood-flow visualization by means of laser specklephotography," Investigative Ophthalmology&Visual Science, vol.22, pp.255-9, Feb1982.
[9] J. D. Briers,"Laser Doppler, speckle and related techniques for blood perfusion mapping andimaging," Physiological Measurement, vol.22,2001.
[10] A. Dunn, et al.,"Dynamic imaging of cerebral blood flow using laser speckle," Journal of CerebralBlood Flow&Metabolism, vol.21, pp.195-201,2001.
[11] B. Ruth,"Measuring the steady-state value and the dynamics of the skin blood flow using thenon-contact laser speckle method," Medical Engineering&Physics, vol.16, pp.105-11,1994.
[12] Y. Tamaki, et al.,"Noncontact, two-dimensional measurement of retinal microcirculation using laserspeckle phenomenon," Investigative Ophthalmology&Visual Science, vol.35, pp.3825-3834,1994.
[13] K. Yaoeda, et al.,"Measurement of microcirculation in the optic nerve head by laser speckleflowgraphy and scanning laser Doppler flowmetry," American Journal of Ophthalmology, vol.129,pp.734-9, Jun2000.
[14] H. Cheng, et al.,"Laser speckle imaging of blood flow in microcirculation," Physics in MedicineAnd Biology, vol.49, pp.1347-57,2004.
[15]程海英, et al.,"对药物作用下大鼠肠系膜上区域性血流变化的实时动态光学监测,"自然科学进展, vol.13, pp.198-201,2003.
[16] C. Zhou, et al.,"Acute functional recovery of cerebral blood flow after forebrain ischemia in rat,"Journal of Cerebral Blood Flow&Metabolism, vol.28, pp.1275-84,2008.
[17] S. K. Nadkarni, et al.,"Characterization of atherosclerotic plaques by laser speckle imaging,"Circulation, vol.112, p.885,2005.
[18] D. Zhu, et al.,"Monitoring thermal-induced changes in tumor blood flow and microvessels withlaser speckle contrast imaging," Applied Optics, vol.46, pp.1911-7,2007.
[19] W. Lau, et al.,"Spatiotemporal characteristics of low-frequency functional activation measured bylaser speckle imaging," IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol.13, pp.179-85,2005.
[20] N. Li, et al.,"High spatiotemporal resolution imaging of the neurovascular response to electricalstimulation of rat peripheral trigeminal nerve as revealed by in vivo temporal laser speckle contrast,"Journal of neuroscience methods, vol.176, pp.230-6,2009.
[21] D. A. Boas and A. K. Dunn,"Laser speckle contrast imaging in biomedical optics," Journal ofBiomedical Optics, vol.15, p.011109,2010.
[22] J. C. Dainty,"Laser speckle and related phenomena," Berlin and New York, Springer-Verlag,1975.
[23] J. Briers,"Wavelength dependence of intensity fluctuations in laser speckle patterns from biologicalspecimens," Optics Communications, vol.13, pp.324-6,1975.
[24] M. D. Stern,"In vivo evaluation of microcirculation by coherent light scattering," Nature, vol.254,pp.56-8,1975.
[25] A. F. Fercher and J. D. Briers,"Flow visualization by means of single-exposure specklephotography," Optics Communications, vol.37, pp.326-30,1981.
[26] S. Ul'yanov, et al.,"The application of speckle interferometry for the monitoring of blood andlymph flow in microvessels," Lasers in Medical Science, vol.12, pp.31-41,1997.
[27] J. S. Paul, et al.,"Imaging the development of an ischemic core following photochemically inducedcortical infarction in rats using Laser Speckle Contrast Analysis (LASCA)," NeuroImage, vol.29,pp.38-45,2006.
[28] P. Miao, et al.,"High Resolution Cerebral Blood Flow Imaging by Registered Laser SpeckleContrast Analysis," IEEE Transactions on Biomedical Engineering, vol.57, pp.1152-7,2010.
[29] Z. Wang, et al.,"Peri-infarct temporal changes in intrinsic optical signal during spreadingdepression in focal ischemic rat cortex," Neuroscience letters, vol.424, pp.133-8,2007.
[30] Q. Liu, et al.,"Laser speckle contrast imaging: monitoring blood flow dynamics and vascularstructure of photodynamic therapy," Proceedings of SPIE, vol.5630, p.26,2005.
[31] T. Durduran, et al.,"Spatiotemporal quantification of cerebral blood flow during functionalactivation in rat somatosensory cortex using laser-speckle flowmetry," Journal of Cerebral BloodFlow&Metabolism, vol.24, pp.518-25,2004.
[32] H. Z. Cummins, Photon correlation spectroscopy and velocimetry: Plenum Pub Corp,1977.
[33] H. Fujii, et al.,"Blood flow observed by time-varying laser speckle," Optics letters, vol.10, pp.104-6,1985.
[34] H. Fujii, et al.,"Evaluation of blood flow by laser speckle image sensing. Part1," Applied Optics,vol.26, pp.5321-5,1987.
[35] B. Ruth,"Non-contact blood flow determination using a laser speckle method," Optics&LaserTechnology, vol.20, pp.309-16,1988.
[36] J. D. Briers and S. Webster,"Laser Speckle Contrast Analysis (LASCA): A Nonscanning, Full-FieldTechnique for Monitoring Capillary Blood Flow," Journal of Biomedical Optics, vol.1, pp.174,1996.
[37] C. M. Waterman-Storer, et al.,"Fluorescent speckle microscopy, a method to visualize the dynamicsof protein assemblies in living cells," Current biology, vol.8, pp.1227-30,1998.
[38] R. Bandyopadhyay, et al.,"Speckle-visibility spectroscopy: A tool to study time-varying dynamics,"Review of Scientific Instruments, vol.76, pp.093110,2005.
[39] S. Kirkpatrick, et al.,"Detrimental effects of speckle-pixel size matching in laser speckle contrastimaging," Optics letters, vol.33, pp.2886-8,2008.
[40] D. Duncan, et al.,"Statistics of local speckle contrast," Journal of the Optical Society of America A,vol.25, pp.9-15,2008.
[41] W. J. Tom, et al.,"Efficient processing of laser speckle contrast images," IEEE Transactions onMedical Imaging, vol.27, pp.1728-38,2008.
[42] S. Liu, et al.,"Fast blood flow visualization of high-resolution laser speckle imaging data usinggraphics processing unit," Optics Express, vol.16, pp.14321-9,2008.
[43] W. Tom, et al.,"Efficient processing of laser speckle contrast images," IEEE Transactions onMedical Imaging, vol.27, pp.1728-38,2008.
[44] A. B. Parthasarathy, et al.,"Robust flow measurement with multi-exposure speckle imaging,"Optics Express, vol.16, pp.1975-89,2008.
[45] P. Miao, et al.,"Random process estimator for laser speckle imaging of cerebral blood flow," OpticsExpress, vol.18, pp.218-36,2010.
[46] P. Miao, et al.,"Imaging the Cerebral Blood Flow With Enhanced Laser Speckle Contrast Analysis(eLASCA) by Monotonic Point Transformation," IEEE Transactions on Biomedical Engineering,vol.56, pp.1127-33,2009.
[47] P. Miao, et al.,"Detecting Cerebral Arteries and Veins: from Large to Small," Journal of InnovativeOptical Health Sciences, vol.3, pp.61-7,2010.
[48] N. Hecht, et al.,"Intraoperative monitoring of cerebral blood flow by laser speckle contrastanalysis," Neurosurgical Focus, vol.27, p. E11,2009.
[49] P. G. McGuire and T. R. Howdieshell,"The Importance of Engraftment in Flap Revascularization:Confirmation by Laser Speckle Perfusion Imaging," Journal of Surgical Research,2010.
[50] M. Roustit, et al.,"Excellent reproducibility of laser speckle contrast imaging to assess skinmicrovascular reactivity," Microvascular Research, vol80, pp.505-11,2010.
[51] G. Mahe, et al.,"Laser speckle contrast imaging accurately measures blood flow over moving skinsurfaces," Microvascular Research, pp.183-8,2010.
[52] C. M. Treu, et al.,"Sidestream dark field imaging: the evolution of real-time visualization ofcutaneous microcirculation and its potential application in dermatology," Archives ofDermatological Research, pp.1-10,2011.
[53] J. D. Briers,"Laser speckle contrast imaging for measuring blood flow," Optica Applicata, vol.37, p.139,2007.
[54]骆清铭, et al.,"脑功能光学成像,"首届全国功能神经影像学和神经信息学研讨会论文汇编,2003.
[55] A. Villringer and B. Chance,"Non-invasive optical spectroscopy and imaging of human brainfunction," Trends in neurosciences, vol.20, pp.435-42,1997.
[56] Available: http://www-sop.inria.fr/members/Maureen.Clerc/functionalimagingbrain.php
[57] C. Roy and C. Sherrington,"On the regulation of the blood-supply of the brain," The Journal ofphysiology, vol.11, p.85,1890.
[58] A. Villringer and U. Dirnagl,"Coupling of brain activity and cerebral blood flow: basis of functionalneuroimaging," Cerebrovascular and Brain Metabolism Reviews, vol.7, p.240,1995.
[59] D. Heeger and D. Ress,"What does fMRI tell us about neuronal activity?" Nature ReviewsNeuroscience, vol.3, pp.142-51,2002.
[60] K. H. Polderman,"Application of therapeutic hypothermia in the ICU: opportunities and pitfalls of apromising treatment modality. Part1: Indications and evidence," Intensive Care Medicine, vol.30,pp.556-75,2004.
[61] K. C. Wong,"Physiology and pharmacology of hypothermia," Western Journal of Medicine, vol.138, pp.227-32,1983.
[62] L. W. Smith and T. Fay,"Observations on human beings with cancer maintained at reducedtemperature of75-90Fahrenheit (24-32C)," American Journal of Clinical Pathology, vol.10, pp.1-11,1940.
[63] T. Fay,"Observations on generalized refrigeration in cases of severe cerebral trauma," Assoc ResNerv Ment Dis Proc, vol.24, pp.611-9,1943.
[64] J. H. Talbott,"The physiologic and therapeutic effects of hypothermia," New England Journal ofMedicine, vol.224, pp.281-8,1941.
[65] W. G. Bigelow, et al.,"Hypothermia; its possible role in cardiac surgery: an investigation of factorsgoverning survival in dogs at low body temperatures," Annals of Surgery, vol.132, pp.849-66,1950.
[66] H. L. Rosomoff and P. Safar,"Management of the comatose patient," Clinical Anesthesia, vol.1, pp.244-58,1965.
[67] R. Busto, et al.,"Small differences in intraischemic brain temperature critically determine the extentof ischemic neuronal injury," Journal of Cerebral Blood Flow&Metabolism, vol.7, pp.729-38,Dec1987.
[68] G. L. Clifton, et al.,"Lack of Effect of Induction of Hypothermia after Acute Brain Injury," NewEngland Journal of Medicine, vol.344, p.556,2001.
[69] G. L. Clifton, et al.,"Marked protection by moderate hypothermia after experimental traumatic braininjury," Journal of Cerebral Blood Flow&Metabolism, vol.11, pp.114-21,1991.
[70]李承晏and刘传玉,"亚低温联合升压治疗对局灶性脑缺血的脑保护作用,"中国危重病急救医学, vol.14, pp.684-5,2002.
[71]许鹏程and陈群,"亚低温对脑缺血后延迟性神经元坏死的影响,"徐州医学院学报, vol.18, pp.455-7,1998.
[72]朱长连, et al.,"低温对新生大鼠缺氧缺血性脑损伤的保护作用及其机制,"中华儿科杂志, vol.41, pp.911-5,2003.
[73]刘登礼, et al.,"振幅整合脑电图在新生儿缺氧缺血性脑病诊断中的应用价值,"临床儿科杂志,vol.23, pp.324-5,2005.
[74]邵肖梅,"新生儿缺氧缺血性脑病的亚低温治疗,"中国实用儿科杂志, vol.21, pp.647-50,2006.
[75]汪吉梅,"选择性头部亚低温治疗新生猪缺氧缺血性脑损伤脑电生理的变化,"2005.
[76]汪吉梅, et al.,"亚低温对新生猪缺氧缺血脑损伤振幅整合脑电图变化的影响,"中国当代儿科杂志, vol.7, pp.159-62,2005.
[77] P. D. Lyden, et al.,"Therapeutic hypothermia for acute stroke," International Journal of Stroke, vol.1, pp.9-19,2006.
[78] N. C. Care,"Induced hypothermia in critical care medicine: A review," Critical Care Medicine, vol.31, p.2041,2003.
[79] T. M. Hemmen and P. D. Lyden,"Induced hypothermia for acute stroke," Stroke, vol.38, p.794,2007.
[80] S. A. Bernard, et al.,"Treatment of comatose survivors of out-of-hospital cardiac arrest withinduced hypothermia," New England Journal of Medicine, vol.346, pp.557-63,2002.
[81] P. J. Safar and P. M. Kochaned,"Mild therapeutic hypothermia to improve the neurologic outcomeafter cardiac arrest," New England Journal of Medicine, vol.346, pp.612-3,2002.
[82] D. L. Taylor, et al.,"Improved neuroprotection with hypothermia delayed by6hours followingcerebral hypoxia-ischemia in the14-day-old rat," Pediatric Research, vol.51, pp.13-9,2002.
[83] J. P. Nolan, et al.,"Therapeutic hypothermia after cardiac arrest. An advisory statement by theAdvancement Life support Task Force of the International Liaison committee on Resuscitation,"Resuscitation, vol.57, pp.231-5,2003.
[84] K. Niwa, et al.,"Mild hypothermia disturbs regional cerebrovascular autoregulation in awake rats,"Brain Research, vol.789, pp.68-73,1998.
[85] W. E. Hoffman and C. Thomas,"Effects of graded hypothermia on outcome from brain ischemia,"Neurological Research, vol.18, pp.185-9,1996.
[86] J. W. Kuluz, et al.,"Selective brain cooling increases cortical cerebral blood flow in rats," AmericanJournal of Physiology-Heart and Circulatory Physiology, vol.265, pp.824-7,1993.
[87] W. Wang, et al.,"A preliminary study on determining the time window of hypothermia cerebralprotection in rat cortex by laser speckle flowmetry," Proceedings of SPIE, vol.6445, p.64450Q,2007.
[88] L. I. Goldfischer,"Autocorrelation function and power spectral density of laser-produced specklepatterns," Journal of the Optical Society of America, vol.55, pp.247-53,1965.
[89] J. D. Briers,"Holographic, speckle and moiré techniques in optical metrology," Progress inQuantum Electronics, vol.17, pp.167-233,1993.
[90] A. K. Dunn, et al.,"Simultaneous imaging of total cerebral hemoglobin concentration, oxygenation,and blood flow during functional activation," Optics letters, vol.28, pp.28-30,2003.
[91] H. Cheng, et al.,"Modified laser speckle imaging method with improved spatial resolution,"Journal of Biomedical Optics, vol.8, pp.559-64,2003.
[92] J. D. Rigden and E. I. Gordon,"The granularity of scattered optical maser light," Proc. IRE, vol.50,pp.2367-8,1962.
[93] J. W. Goodman, et al.,"Laser Speckle and Related Phenomena," Statistical Properties of LaserSpeckle Patterns, vol.9, pp.9-75,1975.
[94] A. Serov, et al.,"Speckles in laser Doppler blood flowmetry," Proceedings of SPIE, vol.4242, p.306,2001.
[95] J. Ohtsubo and T. Asakura,"Velocity measurement of a diffuse object by using time-varyingspeckles," Optical and Quantum Electronics, vol.8, pp.523-9,1976.
[96] J. D. Briers,"A note on the statistics of laser speckle patterns added to coherent and incoherentuniform background fields, and a possible application for the case of incoherent addition," Opticaland Quantum Electronics, vol.7, pp.422-4,1975.
[97] H. Z. Cummins and E. R. Pike, Photon correlation spectroscopy and velocimetry: Plenum,1977.
[98] J. D. Briers,"Time-varying laser speckle for measuring motion and flow," Proceedings of SPIE, vol.4242, p.25,2003.
[99] J. W. Goodman,"Some fundamental properties of speckle," Journal of the Optical Society ofAmerica, vol.66, pp.1145-50,1976.
[100] T. S. McKechnie,"Speckle reduction," Laser Speckle and Related Phenomena, pp.123-70,1984.
[101] V. Tuchin, Handbook of optical biomedical diagnostics: Society of Photo Optical,2002.
[102] J. W. Goodman,"Some effects of target-induced scintillation on optical radar performance,"Proceedings of the IEEE, vol.53, pp.1688-700,1965.
[103] B. Berne and R. Pecora, Dynamic light scattering: Wiley New York,1976.
[104] J. W. Goodman,"Some fundamental properties of speckle," Journal of the Optical Society ofAmerica, vol.66, pp.1145-50,1976.
[105] R. Bonner and R. Nossal,"Model for laser Doppler measurements of blood flow in tissue," AppliedOptics, vol.20, pp.2097–107,1981.
[106] M. Draijer, et al.,"Review of laser speckle contrast techniques for visualizing tissue perfusion,"Lasers in Medical Science, vol.24, pp.639-51,2009.
[107] G. Vargas, et al.,"Morphological Changes in Blood Vessels Produced by Hyperosmotic Agents andMeasured by Optical Coherence Tomography," Photochemistry and photobiology, vol.77, pp.541-9,2003.
[108] R. Jain and L. Munn,"Dissecting tumour pathophysiology using intravital microscopy," NatureReviews Cancer, vol.2, pp.266-76,2002.
[109] S. Yuan, et al.,"Determination of optimal exposure time for imaging of blood flow changes withlaser speckle contrast imaging," Applied Optics, vol.44, pp.1823-30, Apr12005.
[110] V. Tuchin,"Optical clearing of tissues and blood using the immersion method," Journal of PhysicsD: Applied Physics, vol.38, p.2497,2005.
[111] A. Takasu, et al.,"Mild or moderate hypothermia, but not increased oxygen breathing, increaseslong-term survival after uncontrolled hemorrhagic shock in rats," Critical care medicine, vol.28, pp.2465-74,2000.
[112] S. H. Kim, et al.,"Hypothermia and minimal fluid resuscitation increase survival after uncontrolledhemorrhagic shock in rats," Journal Of Trauma-injury Infection And Critical Care, vol.42, pp.213-22,1997.
[113] L. Ibanez, et al.,"The ITK Software Guide."
[114] N. Otsu,"A threshold selection method from gray-level histograms," IEEE Transactions on Systems,Man, and Cybernetics, vol.9, pp.62-6,1979.
[115]付忠良,"图像阈值选取方法: Otsu方法的推广,"计算机应用, vol.20, pp.37-9,2000.
[116] M. Nemoto, et al.,"Analysis of optical signals evoked by peripheral nerve stimulation in ratsomatosensory cortex: dynamic changes in hemoglobin concentration and oxygenation," Journal ofCerebral Blood Flow&Metabolism, vol.19, pp.246-59,1999.
[117] B. G. Covino and A. H. Hegnauer,"Electrolytes and pH Changes in Relation to HypothermicVentricular Fibrillation," Circulation Research, vol.3, pp.575-80,1955.
[118] J. Biem, et al.,"Out of the cold: management of hypothermia and frostbite," Canadian MedicalAssociation Journal, vol.168, pp.305-11,2003.
[119] B. Walter, et al.,"Coupling of Cerebral Blood Flow and Oxygen Metabolism in Infant Pigs DuringSelective Brain Hypothermia," Journal of Cerebral Blood Flow&Metabolism, vol.20, pp.1215-24,2000.
[120] T. Hishinuma, et al.,"III.1. Changes of Brain Distribution of [11C] methamphetamine byPentobarbital Anesthesia in Mice." CYRIC Annual Report, pp.79-82,2002.
[121] L. Edvinsson, et al., Cerebral blood flow and metabolism vol.27: Lippincott Williams&WilkinsPhiladelphia, PA,2002.
[122] K. S. Hendrich, et al.,"Cerebral perfusion during anesthesia with fentanyl, isoflurane, orpentobarbital in normal rats studied by arterial spin-labeled MRI," Magnetic Resonance in Medicine,vol.46, pp.202-6,2001.
[123] H. C. Wartenberg, et al.,"Pharmacological modification of sodium channels from the human heartatrium in planar lipid bilayers: electrophysiological characterization of responses to batrachotoxinand pentobarbital," European Journal of Anaesthesiology, vol.20, pp.354-62,2005.
[124] R. A. Henker, et al.,"Comparison of brain temperature with bladder and rectal temperatures inadults with severe head injury," Neurosurgery, vol.42, pp.1071-5,1998.
[125] A. Ngai, et al.,"Simultaneous measurements of pial arteriolar diameter and laser-Doppler flowduring somatosensory stimulation," Journal of cerebral blood flow and metabolism: official journalof the International Society of Cerebral Blood Flow and Metabolism, vol.15, p.124,1995.
[126] J. Detre, et al.,"Signal averaged laser Doppler measurements of activation-flow coupling in the ratforepaw somatosensory cortex," Brain Research, vol.796, pp.91-8,1998.
[127] T. Woolsey, et al.,"Neuronal units linked to microvascular modules in cerebral cortex: responseelements for imaging the brain," Cerebral Cortex, vol.6, p.647,1996.
[128] A. Silva, et al.,"Simultaneous blood oxygenation level-dependent and cerebral blood flowfunctional magnetic resonance imaging during forepaw stimulation in the rat," Journal of CerebralBlood Flow&Metabolism, vol.19, pp.871-9,1999.
[129] L. Pelosi, et al.,"The effect of stimulus frequency on spinal and scalp somatosensory evokedpotentials to stimulation of nerves in the lower limb," Electroencephalography and clinicalneurophysiology. Supplement, vol.41, p.149,1990.
[130] T. Matsuura, et al.,"CBF change evoked by somatosensory activation measured by laser-Dopplerflowmetry: independent evaluation of RBC velocity and RBC concentration," The Japanese Journalof Physiology, vol.49, pp.289-96,1999.
[131] F. Hyder, et al.,"Dynamic magnetic resonance imaging of the rat brain during forepaw stimulation,"Journal of cerebral blood flow and metabolism: official journal of the International Society ofCerebral Blood Flow and Metabolism, vol.14, p.649,1994.
[132] S. Keilholz, et al.,"Functional MRI of the rodent somatosensory pathway using multislice echoplanar imaging," Magnetic Resonance in Medicine, vol.52, pp.89-99,2004.
[133] N. Camp, et al.,"Stimulation of the rat somatosensory cortex at different frequencies and pulsewidths," NMR in Biomedicine, vol.19, pp.10-7,2006.
[134] S. Narayan,"Functional increases in cerebral blood volume over somatosensory cortex," Journal ofCerebral Blood Flow&Metabolism, vol.15, pp.754-65,1995.
[135] P. Fox and M. Raichle,"Focal physiological uncoupling of cerebral blood flow and oxidativemetabolism during somatosensory stimulation in human subjects," Proceedings of the NationalAcademy of Sciences of the United States of America, vol.83, p.1140,1986.
[136] M. Jones, et al.,"Concurrent optical imaging spectroscopy and laser-Doppler flowmetry: therelationship between blood flow, oxygenation, and volume in rodent barrel cortex," NeuroImage, vol.13, pp.1002-15,2001.
[137] J. Mayhew, et al.,"Increased oxygen consumption following activation of brain: theoreticalfootnotes using spectroscopic data from barrel cortex," NeuroImage, vol.13, pp.975-87,2001.
[138] S. A. Sheth, et al.,"Linear and nonlinear relationships between neuronal activity, oxygenmetabolism, and hemodynamic responses," Neuron, vol.42, pp.347-55,2004.
[139] J. Wall and C. Cusick,"Cutaneous responsiveness in primary somatosensory (SI) hindpaw cortexbefore and after partial hindpaw deafferentation in adult rats," Journal of Neuroscience, vol.4, p.1499,1984.
[140] J. Snyman, Practical mathematical optimization: an introduction to basic optimization theory andclassical and new gradient-based algorithms, Springer Verlag,2005.
[141] C. H. Chen-Bee, et al.,"Areal extent quantification of functional representations using intrinsicsignal optical imaging," Journal of Neuroscience Methods, vol.68, pp.27-37,1996.
[142] J. Martindale, et al.,"The hemodynamic impulse response to a single neural event," Journal ofCerebral Blood Flow&Metabolism, vol.23, pp.546-55, May2003.
[143] B. Ances, et al.,"Coupling of neural activation to blood flow in the somatosensory cortex of rats istime-intensity separable, but not linear," Journal of Cerebral Blood Flow&Metabolism, vol.20, pp.921-30,2000.
[144] T. Matsuura and I. Kanno,"Quantitative and temporal relationship between local cerebral bloodflow and neuronal activation induced by somatosensory stimulation in rats," Neuroscience Research,vol.40, pp.281-90,2001.
[145] W. Grill Jr and J. Mortimer,"The effect of stimulus pulse duration on selectivity of neuralstimulation," IEEE Transactions on Biomedical Engineering, vol.43, pp.161-6,2002.
[146] A. Dunn, et al.,"Spatial extent of oxygen metabolism and hemodynamic changes during functionalactivation of the rat somatosensory cortex," NeuroImage, vol.27, pp.279-90,2005.
[147] A. Devor, et al.,"Coupling of total hemoglobin concentration, oxygenation, and neural activity inrat somatosensory cortex," Neuron, vol.39, pp.353-9,2003.
[148] S. Sheth, et al.,"Columnar specificity of microvascular oxygenation and volume responses:implications for functional brain mapping," Journal of Neuroscience, vol.24, p.634,2004.
[149] S. A. Bernard and M. Buist,"Induced hypothermia in critical care medicine: a review," Critical CareMedicine, vol.31, pp.2041-51,2003.
[150] K. R. Diller and L. Zhu,"Hypothermia therapy for brain injury," Annual Review of BiomedicalEngineering, vol.11, pp.135-62,2009.
[151] P. Bath,"Re: Stroke Therapy Academic Industry Roundtable II (STAIR-II)," Stroke, vol.33, pp.639-40,2002.
[152] V. E. O'Collins, et al.,"Experimental treatments in acute stroke," Annals of Neurology, vol.59, pp.467-77,2006.
[153] M. Erecinska, et al.,"Effects of hypothermia on energy metabolism in mammalian central nervoussystem," Journal of Cerebral Blood Flow&Metabolism, vol.23, pp.513-30,2003.
[154] K. Nakashima and M. M. Todd,"Effects of hypothermia on the rate of excitatory amino acid releaseafter ischemic depolarization," Stroke, vol.27, pp.913-8,1996.
[155] R. Busto, et al.,"Effect of mild hypothermia on ischemia-induced release of neurotransmitters andfree fatty acids in rat brain," Stroke, vol.20, pp.904-10,1989.
[156] J. S. Beckman and W. H. Koppenol,"Nitric oxide, superoxide, and peroxynitrite: the good, the bad,and ugly," American Journal of Physiology: Cell Physiology, vol.271, pp. C1424-37,1996.
[157] C. Iadecola,"Regulation of the cerebral microcirculation during neural activity: is nitric oxide themissing link?" Trends in Neurosciences, vol.16, pp.206-14,1993.
[158] Y. Liu, et al.,"The temporal response of the brain after eating revealed by functional MRI," Nature,vol.405, pp.1058-62,2000.
[159] N. Ramsey, et al.,"Functional MRI experiments: acquisition, analysis and interpretation of data,"European Neuropsychopharmacology, vol.12, pp.517-26,2002.
[160] R. Baumgartner, et al.,"Resampling as a cluster validation technique in fMRI," Journal of MagneticResonance Imaging, vol.11, pp.228-31,2000.
[161] Y. Shu, et al.,"Turning on and off recurrent balanced cortical activity," Nature, vol.423, pp.288-93,2003.
[162] E. Hillman, et al.,"Depth-resolved optical imaging and microscopy of vascular compartmentdynamics during somatosensory stimulation," NeuroImage, vol.35, pp.89-104,2007.
[163] J. C. Rajapakse, et al.,"Modeling hemodynamic response for analysis of functional MRItime-series," Human Brain Mapping, vol.6, pp.283-300,1998.
[164] M. Svensen, et al.,"Probabilistic modeling of single-trial fMRI data," IEEE Transactions onMedical Imaging, vol.19, pp.25-35,2002.
[165] R. D. Dripps and R. W. Virtue,"The Physiology of Induced Hypothermia. Proceedings of aSymposium," Anesthesiology, vol.19, p.118,1958.
[166] E. A. Kiyatkin,"Brain hyperthermia as physiological and pathological phenomena," Brain ResearchReviews, vol.50, pp.27-56,2005.
[167] G. Royl, et al.,"Hypothermia effects on neurovascular coupling and cerebral metabolic rate ofoxygen," NeuroImage, vol.40, pp.1523-32,2008.
[168] T. Deboer and I. Tobler,"Temperature dependence of EEG frequencies during natural hypothermia,"Brain research, vol.670, pp.153-6,1995.
[169] X. H. Zhu, et al.,"Noninvasive and three-dimensional imaging of CMRO2in rats at9.4T:reproducibility test and normothermia/hypothermia comparison study," Journal of Cerebral BloodFlow&Metabolism, vol.27, pp.1225-34,2006.
[170] P. Krafft, et al.,"Mild and Moderate Hypothermia ({alpha}-Stat) Do Not Impair the CouplingBetween Local Cerebral Blood Flow and Metabolism in Rats Editorial Comment," Stroke, vol.31,pp.1393-400,2000.
[171] R. Duelli and W. Kuschinsky,"Changes in brain capillary diameter during hypocapnia andhypercapnia," Journal of Cerebral Blood Flow&Metabolism, vol.13, pp.1025-8,1993.
[172] C. Iadecola, et al.,"Local and propagated vascular responses evoked by focal synaptic activity incerebellar cortex," Journal of Neurophysiology, vol.78, pp.651-9,1997.
[173] A. Villringer, et al.,"Capillary perfusion of the rat brain cortex. An in vivo confocal microscopystudy," Circulation Research, vol.75, pp.55-62,1994.
[174] A. Gjedde and M. Rasmussen,"Blood-brain glucose transport in the conscious rat: comparison ofthe intravenous and intracarotid injection methods," Journal of Neurochemistry, vol.35, pp.1375-81,1980.
[175] M. Ueki, et al.,"Effect of alpha-chloralose, halothane, pentobarbital and nitrous oxide anesthesia onmetabolic coupling in somatosensory cortex of rat," Acta Anaesthesiologica Scandinavica, vol.36,pp.318-22,1992.
[176] S. Nagahiro, et al.,"Pathophysiology and treatment of cerebral ischemia," The Journal of MedicalInvestigation, vol.45, p.57,1998.
[177] H. Kato, et al.,"Temporal profile of the effects of pretreatment with brief cerebral ischemia on theneuronal damage following secondary ischemic insult in the gerbil: cumulative damage andprotective effects," Brain Research, vol.553, pp.238-42,1991.
[178] K. Overgaard, et al.,"A rat model of reproducible cerebral infarction using thrombotic blood clotemboli," Journal of Cerebral Blood Flow&Metabolism, vol.12, pp.484-90,1992.
[179] J. Koizumi, et al.,"Experimental studies of ischemic brain edema, I: a new experimental model ofcerebral embolism in rats in which recirculation can be introduced in the ischemic area," JapaneseJournal of Stroke, vol.8, pp.1-8,1986.
[180] K. A. Hossmann,"Reperfusion of the brain after global ischemia: hemodynamic disturbances,"Shock, vol.8, p.95,1997.
[181] A. Green,"Pharmacological approaches to acute ischaemic stroke: reperfusion certainly,neuroprotection possibly," British journal of pharmacology, vol.153, pp. S325-38,2008.
[182] D. S. Liebeskind,"Collateral circulation," Stroke, vol.34, p.2279,2003.
[183] D. S. Liebeskind,"Collaterals in acute stroke: beyond the clot," Neuroimaging Clinics of NorthAmerica, vol.15, pp.553-73,2005.
[184] W. K. Pratt,"Digital image processing: PIKS inside,"2001.
[185] D. R. Cox and D. Oakes, Analysis of survival data. Chapman&Hall/CRC,1984.
[186] K. Zuiderveld,"Contrast limited adaptive histogram equalization," pp.474-85,1994.
[187] H. K. Shin, et al.,"Mild induced hypertension improves blood flow and oxygen metabolism intransient focal cerebral ischemia," Stroke, vol.39, p.1548,2008.
[188]O. Y. Bang, et al.,"Impact of collateral flow on tissue fate in acute ischaemic stroke," Journal of Neurology, Neurosurgery&Psychiatry, vol.79, p.625,2008.
[189]王拥军.统计显示中风正向中青年入侵.北京科技报,2009.Available：http://tech.sina.com.cn/d/2009-01-05/14472718512.shtml
[190]张微微,”重新认识短暂性脑缺血发作,”中华老年心脑血管病杂志,vol.4,pp.75-7,2002.
[191]B. Schmitz, et al.,"Recovery of the rodent brain after cardiac arrest:A functional MRI study," Magnetic resonance in medicine, vol.39, pp.783-8,1998.
[192]B. M. Ances, et al.,"Acute carotid occlusion alters the activation flow coupling response to forepaw stimulation in a rat model. Editorial comment," Stroke, vol.31, pp.955-60,2000.
[193]R. M. Dijkhuizen, et al.,"Correlation between Brain Reorganization, Ischemic Damage, and Neurologic Status after Transient Focal Cerebral Ischemia in Rats:A Functional Magnetic Resonance Imaging Study," Journal of Neuroscience, vol.23, p.510,2003.