近紅外光譜儀（NIRS）是一種使用電磁波譜（波長范圍為700-900nm）的非侵入性腦成像技術，通過確定組織的光學特性來測量血紅蛋白濃度和氧飽和度。已經許多研究顯示了近紅外光譜儀用於監測腦血管疾病（例如中風）中的腦血流動力學的臨床潛力。 然而，研究中測量的不一致性被認為部分地歸因於解剖學差異和疾病呈現的多樣性，限制了NIRS用於中風監測的臨床可行性。在本研究中，我們首先應用頸總動脈結紮，以觀察快速的血液動力學變化。其次，對具有兩種類型的梗塞嚴重性的大腦中腦動脈閉塞（MCAO）大鼠（Koizumi’s方法）利用近紅外光譜儀進行了生物雙腦半球頻域測量。為了估計由大腦中腦動脈閉塞手術誘導的腦梗塞的程度，用2,3,5-三苯基四唑氯化物（TTC）（1.08380.0010，Merck Millipore）染色腦的冠狀切片用於組織學分析。與輕度梗死相比，嚴重梗塞的半球在急性閉塞期間表現出較低的血氧飽和度，而灌注早期的雙腦半球間相關係數（IHCC）較低，並且灌注後期的散射係數（μs'）較低。雙腦半球間相關係數是區域微灌注的生物標誌物，用於驗證由動態腦自動調節中斷引起的異常半球微血管血流動力學，這可以提供梗塞面積相關的強有力證據。急性閉塞期間血紅蛋白濃度和血液飽和度的變化。有趣的是，在早期再灌注階段出現的血流動力學振蕩的半球間同步性差異與三天后發生的梗塞面積有關。最後，更強的組織散射可能反映了腦水腫的程度。
基於大腦中腦動脈閉塞動物模型和雙腦半球間相關係數觀察，最終目標是將這些技術應用於中風患者的臨床試驗。這些近紅外光譜儀參數可能有可能成為未來轉化研究中長期卒中風監測的早期預後生物標誌物。

Near-infrared spectroscopy (NIRS) is a non-invasive brain imaging technique using electromagnetic spectrum (wavelength ranges from 700-900nm) that measures hemoglobin concentration and oxygen saturation by determining the optical properties of tissue. Clinical potential of NIRS for monitoring cerebral hemodynamics in cerebrovascular diseases, such as stroke, has been studied. However, inconsistencies in measurements among studies, which are believed to be partly due to anatomical variance and diversity in disease presentation, limit the clinical feasibility of NIRS for stroke monitoring. In the present study, we first apply common carotid artery ligation to see the rapid hemodynamic changes. Secondly, frequency-domain NIRS measurements on hemispheres of middle cerebral artery occlusion (MCAO) rats (Koizumi’s method) with two types of infarction severity were performed. To estimate the extent of brain infarction induced by the MCAO surgery, coronal sections of the brain were stained with 2,3,5-triphenyltetrazolium chloride (TTC) (1.08380.0010, Merck Millipore) for histological analysis. Compared to minor infarction, the severely infarcted hemispheres showed lower blood oxygenation during acute occlusion, a lower interhemispheric correlation coefficient (IHCC) during the early stage of reperfusion, and a higher reduced scattering coefficient (μs’) in the late stage of reperfusion. The inter-hemispheric correlation coefficient (IHCC), a biomarker of regional micro-perfusion, is used for validating abnormal hemispheric micro-vascular hemodynamics resulting from disruption in dynamic cerebral auto-regulation, which could provide a strong evidence of infarct-size-related changes in hemoglobin concentration and blood saturation during acute occlusion. Interestingly, the discrepancy in interhemispheric synchronicity in hemodynamic oscillation appeared during the early reperfusion stage is related to the size of infarct developed three days later. Finally, the stronger tissue scattering might reflect the degree of brain edema. The ultimate goal is to apply these NIRS techniques and parameters as early prognostic biomarkers for long-term stroke monitoring in the future translational investigation.

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