脑血管功能储备评估的方法学

应用单光子发射计算机断层(SPECT)结合放射性标记的同位素示踪剂，如IMP、^99mTc-HMPAO与^99mTc-ECD和^133Xe，至今仍作为测定脑血流量(CBF)的金标准。正电子发射断层扫描(PET)可通过放射性同住素标记的氧、葡萄糖或其他化舍物间接地测定CBF。动态的或功能的核磁共振成像通过去氧血红蛋白或氧敏感的成像技术评估CBF。CT成像技术与^133Xe清除率联合应用测定CBF，从1978年至今，仍可视为另一种CBF测定的金标准，其敏感性与特异性均超过60％。TCD作为无创的脑血流速度检测技术，直到1990年以后才始用于脑血管反应性的检测。所有的上述检测技术或方法，在一些特异的脑血管舒张剂或方法应用之前，均不能准确测定脑血管功能储备(CRC)。只是当这些方法与特异性的脑血管舒张剂或方法，如应用乙酰唑胺、吸入二氧化碳或短时间屏气联合应用时，CRC的检测可成为可能。

The methodology of assessment of cerebrovascular reserve capacity

Single-photon emission computed tomography (SPECT) was applied to measure cerebral flood flow (CBF) directly by using radioactive tracers (i. e. IMP, 99mTc-HMPAO,99mTc-ECD and 133Xenon), and is still taken as standard method even now. Positron emission tomography (PET) was applied to measure CBF indirectly, but it could measure the tissue's metabolism of oxygen, glucose or other chemical materials on which radioactive tracers were labelled. Dynamic MRI and fMRI were applied to evaluate CBF by means of deoxyhemoglobin /oxygenation- sensitive imaging. CT combined 133 Xenon-clearance method was taken as another standard method to measure CBF from 1978 even to today. After inhalation or injection of 133Xenon, CT was required to scan, and the sensitivity and specificity were both over 60% by this method. Transcranial Doppler sonographic technique (TCD) was a noninvasive method to measure blood flow velocity easily, but it was not used to detect the reactivity until 1990. All above these techniques could not be used to measure the cerebrovascular reserve capacity (CRC) until some specious cerebrovasodilators were applied to detect the reactivity of cerebral blood vessels. Only after these vasodilators (i. e. injection of acetazolamide, inhalation of CO2 and apnea) were combined with above techniques, the assessment of CRC would become possible.