NONINVASIVE MEASUREMENT OF INTRACRANIAL PRESSURE

颅内压升高（ICP）仍然是治疗神经系统疾病患者的关键问题，也是这些患者最常见的死亡原因。 如果在早期发现，可以管理和治疗ICP升高。 因此，测量ICP对于诊断和治疗决策是重要的。 目前，只有侵入性技术可用于测量绝对ICP。 这些技术需要物理穿透中枢神经系统（CNS）。本课题的目的是研究颅内压的无创测量技术。 ICP的非侵入性测量将以较低的成本并且对患者没有风险或痛苦。 因此，这一重要的临床参数将被更频繁地测量，并可能显着改善神经系统问题患者的诊断和治疗决策。拟议的项目整合了人类神经生理学，流体动力学原理和动态MRI技术的知识，开发了一种新的方法来非侵入性地测量ICP。 该技术是新颖的，因为它利用了在每个心动周期中自然发生的颅内容积（ICV）和ICP的变化，而不是通过外部干预改变CNS的状态。由于颅内压和体积变化的比率是ICP的已知函数，因此这些变化的比率的测量提供了ICP的测量。 将根据脑脊液（CSF）和血液体积流速的MRI测量值计算心动周期期间ICP和ICV的变化。ICV变化将从进入颅骨的血液和CSF的净体积流量中获得。 将根据脉动CSF压差估计ICP变化。 将根据颈椎中的动态MRI CSF流量测量值计算CSF压力梯度。 在对狒狒的初步研究中，ICP的变化（即，峰-峰脉动ICP）与脉动CSF压力梯度的峰-峰线性相关。 该项目的目的是证明所提出的技术的可行性。具体目标是：1.优化MRI方案和数据分析，以确保ICV变化和压力梯度测量的重现性和准确性。 2.使用动物模型和计算流体动力学模拟评价根据CSF压力梯度测量值估计的ICP变化的准确性。3.通过在正常和升高的ICP动物模型上与有创测量进行比较，评价无创技术的准确性。

Elevated intracranial pressure (ICP) remains a critical problem in management of patients with neurological problems and is the most common cause of death in these patients. Elevated ICP can be managed and treated if detected at an early stage. Therefore, measurement of ICP is important for diagnosis and treatment decisions. At present, only invasive techniques are available for measurement of absolute ICP. These techniques require physical penetration of the central nervous system (CNS). The objective of this project is to develop the technology for non-invasive measurement of ICP. The non-invasive measurement of ICP would be at a lower cost and without risk or pain to the patient. Hence, this important clinical parameter would be measured more often and may significantly improve the diagnosis and treatment decisions for patients with neurological problems. The proposed project integrates knowledge from human neuro-physiology, principles of fluid dynamics, and dynamic MRI techniques in developing a novel method to non-invasively measure ICP. The technique is novel as it makes use of the change in intracranial volume (ICV) and ICP that occur naturally during each cardiac cycle rather than altering the state of the CNS by external intervention. Since the ratio of intracranial pressure and volume changes is a known function of ICP, a measurement of the ratio of these changes provides a measure of ICP. The changes in ICP and ICV during the cardiac cycle will be computed from MRI measurements of cerebrospinal fluid (CSF) and blood volumetric flow rates. The ICV change will be obtained from the net volumetric flow of blood and CSF into the cranium. The ICP changes will be estimated from pulsatile CSF pressure gradient. The CSF pressure gradient will be computed from dynamic MRI CSF flow measurement in the cervical spine. In preliminary work on a baboon, the change in ICP (i.e., the peak-to-peak pulsatile ICP) was linearly correlated with the peak-to-peak of the pulsatile CSF pressure gradient. The objective of this project is to demonstrate the feasibility of the proposed technology. The specific aims are: 1. Optimize the MRI protocol and data analysis for reproducibility and accuracy of ICV change and pressure gradient measurements. 2. Evaluate the accuracy of the estimated ICP changes from CSF pressure gradient measurements using animal model and computational fluid dynamic simulations. 3. Evaluate accuracy of the non-invasive technique by comparison with invasive measurements on an animal model of normal and elevated ICP.