CEREBRAL PERFUSION IMAGING

脑灌注成像

• 批准号: 2271217
• 负责人: PETER M JOSEPH
• 金额: $ 19.36万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-04-20 至 1998-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2271217
• 关键词: blood /plasma substitute; blood flow measurement; carbon dioxide; cats; cerebral cortex; diffusion; magnetic resonance imaging; microcirculation; nitric oxide; perfusion; postmortem; vasodilators

The use of MRI to image cerebral perfusion is an exciting development in clinical MRI. Since the NMR signal can be made exquisitely sensitive to molecular motion by applying gradients in the magnetic field, this technique is called "diffusion weighted imaging" (DWI). However, there are several techniques which do not give consistent results. A group at NIH found that a DWI of water in the brain was related to perfusion at the microvascular level. This result was contradicted by a group at MGH. In each case, it is not clear which technique can reliably distinguish intra- from extra-vascular water. Our experiments utilize fluorinated blood substitutes (FBS), which are strictly intravascular. Since FBS is not now approved for human use, the experiments are done only in animals. Our preliminary experiments have demonstrated that DWI shows a loss of signal of the FBS far in excess of what is known to occur as a result of molecular diffusion; i.e., we have demonstrated a perfusion sensitive MR image. However, our results disagree quantitatively with those of the NIH group and require more study to clarify and characterize the effect. Furthermore, it is desirable to understand the influence of the known vasodilator CO2 as well as the influence of NO synthesis from L-Argine, which alters cerebral perfusion in a selective way. Our MRI technique can distinguish coherent from incoherent flow patterns; a major question is over what time interval does capillary flow mimic incoherent (random) flow. We can also selectively weight the received signal towards the arterial or venus vessels to clarify their relative contributions to the effect. Clarification of these points will improve the scientific basis for diagnosis of many pathologic states, such as infarction, tumor, AVM, etc. when proton DWI is used clinically in humans.

使用 MRI 对脑灌注进行成像是一项令人兴奋的发展 临床磁共振成像。 由于 NMR 信号可以对 通过在磁场中施加梯度来实现分子运动，这 技术称为“弥散加权成像”（DWI）。 然而，有 有几种技术不能给出一致的结果。 一组在 美国国立卫生研究院 (NIH) 发现，大脑中水的 DWI 与脑部灌注有关。 微血管水平。 这一结果与麻省总医院的一个研究小组相矛盾。 在 在每种情况下，尚不清楚哪种技术可以可靠地区分内部 来自血管外的水。 我们的实验使用氟化血液 替代品（FBS），严格来说是血管内的。 由于FBS现在不是 批准用于人类，实验仅在动物身上进行。 我们的 初步实验表明 DWI 显示信号丢失 FBS 的数量远远超过已知的结果 分子扩散；即，我们已经证明了灌注敏感的 MR 图像。 然而，我们的结果在数量上与 NIH 的结果不一致 组并需要更多的研究来澄清和描述其效果。 此外，希望了解已知的影响 血管扩张剂 CO2 以及 L-精氨酸合成 NO 的影响， 它以选择性的方式改变脑灌注。 我们的 MRI 技术可以 区分相干和非相干流动模式；一个主要问题是 毛细管流动在什么时间间隔内模拟不相干（随机） 流动。 我们还可以有选择地对接收到的信号进行加权 动脉或金星血管，以澄清它们对 影响。 澄清这些要点将提高科学依据 用于诊断多种病理状态，如梗死、肿瘤、AVM、 当质子 DWI 用于人体临床时等。