A multimodality investigation of cerebral hemodynamics and autoregulation in pharmacological MRI
A multimodality investigation of cerebral hemodynamics and autoregulation in pharmacological MRI
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DOI：
10.1016/j.mri.2007.03.003
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发表时间：
2007-07-01
影响因子：
2.5
通讯作者：
Bifone, Angelo
中科院分区：
文献类型：
--
作者：
Gozzi, Alessandro;Ceolin, Laura;Bifone, Angelo
药理学MRI （phMRI）方法已被广泛应用于评估中枢血流动力学对药物干预的反应，作为潜在神经元活动变化的替代。然而，许多精神药物也可以影响心血管参数，包括动脉血压（BP）。血压的突然变化或临床前phMRI中使用的麻醉剂可能会损害脑血流（CBF）自动调节机制，潜在地在phMRI反应中引入混淆。此外，通常在小动物phMRI研究中测量的相对脑血容量（rCBV）可能对血压变化敏感，即使存在完整的自动调节。应用激光多普勒血流仪和磁共振成像（MRI）测量氟烷麻醉大鼠静脉注射去甲肾上腺素（NE）增加剂量引起的CBF和微血管CBV的变化。NE是一种有效的血管加压剂，它不会穿过血脑屏障，并模仿急性药物刺激时典型的快速血压变化。我们发现CBF自动调节在60-120 mmHg的血压范围内保持。在这些条件下，没有观察到明显的中枢rCBV反应，这表明微血管rCBV对灌注压力突变的反应在自身调节范围内可以忽略不计。更大的血压反应伴随着CBV和CBF的显著变化，这可能会混淆phMRI结果的解释。(c) 2007爱思唯尔公司版权所有。
Pharmacological MRI (phMRI) methods have been widely applied to assess the central hemodynamic response to pharmacological intervention as a surrogate for changes in the underlying neuronal activity. However, many psychoactive drugs can also affect cardiovascular parameters, including arterial blood pressure (BP). Abrupt changes in BP or the anesthetic agents used in preclinical phMRI may impair cerebral blood flow (CBF) autoregulation mechanisms, potentially introducing confounds in the phMRI response. Moreover, relative cerebral blood volume (rCBV), often measured in small-animal phMRI studies, may be sensitive to BP changes even in the presence of intact autoregulation. We applied laser Doppler flowmetry and MRI to measure changes in CBF and microvascular CBV induced by increasing doses of intravenous norepinephrine (NE) challenge in the halothane-anesthetized rat. NE is a potent vasopressor that does not cross the blood-brain barrier and mimics the rapid BP changes typically observed with acute drug challenges. We found that CBF autoregulation was maintained over a BP range of 60-120 mmHg. Under these conditions, no significant central rCBV responses were observed, suggesting that microvascular rCBV changes in response to abrupt changes in perfusion pressure are negligible within the autoregulatory range. Larger BP responses were accompanied by significant changes in both CBV and CBF that might confound the interpretation of phMRI results. (c) 2007 Elsevier Inc. All rights reserved.