Noninvasive Measurements of Intracranial Pressure, Tissue Compliance, Susceptibility and Temperature Using Magnetic Resonance Imaging

目的：颅内压、组织顺应性和组织温度等物理参数的测量对于脑肿瘤、脑积水等疾病的诊断和治疗具有重要意义。提出了一种基于磁共振的技术来评估颅内压和组织顺应性，该技术基于脑循环等效电路模型的逆分析，其中MR测量的流量被用作电流。对于温度成像，提出了一种新的方法--“复自参考法”。线扫描回波平面光谱成像（LSEPSI）的应用也进行了检查。在下文中，颅内压和组织顺应性的非侵入性测量的结果described.Methods：一个逆分析算法来评估电路中的元素，其中模拟两个主要的脑循环，血液和脑脊液（CSF）流，设计。逆分析的输入是通过相衬速度图获得的CSF流速，而估计函数是从频域中的测量速率估计的动脉血流速的平方误差的和。实验使用脑循环模拟体模，然后通过数值模拟证实，所提出的技术产生的顺应性和压力的相对指数。25名健康人的研究（22-63岁）和9例患者（27-69岁）志愿者进行检查的可行性所提出的技术映射和分组的志愿者在顺应性和压力指数空间。在组织顺应性和颅内压指标构成的二维空间中，健康组和患者组分布在明显不同的区域，证明了所提出的用于对受试者的颅内生物力学性质的状态进行分类的技术的可行性和可行性。

Purpose : Measurements of physical parameters such as intracranical pressure, tissue compliance and tissue temperature are important for diagnosis and management of deceases such as brain tumor and hydrocephalus. A magnetic-resonance-based technique to evaluate intracranial pressure and tissue compliance based on an inverse analysis of a brain-circulation-equivalent electrical circuit model, in which MR-measured flow rates were used as currents, was proposed. For temperature imaging, a new method named "Complex, Self-reference Method" was proposed. Application of the Line Scan Echo Planar Spectroscopic Imaging (LSEPSI) was also examined. In the following, the results of the noninvasive measurement of intracranial pressure and tissue compliance are described.Methods : An inverse analysis algorism to evaluate elements in an electrical circuit, which modeled two major brain circulations, blood and cerebrospinal fluid (CSF) flows, was devised. The input for the inverse analysis was the CSF flow rate obtained by phase-contrast velocity map, whereas the estimation function was the sum of the square error of the estimated arterial blood flow rate from the measured rate in the frequency domain. Experiments using a brain-circulation-mimicking phantom followed by numerical simulations confirmed that the proposed technique yielded relative indices of the compliance and pressure. Studies on 25 healthy (22-63 years old) and 9 patient (27-69 years old) volunteers were performed to examine feasibility of the proposed technique for mapping and grouping the volunteers in the compliance and pressure indices space.Results : The healthy and patient groups distributed in significantly different regions in a two-dimensional space formed by the indices of tissue compliance and intracranial pressure, demonstrating the feasibility and viability of the proposed technique for classifying the statuses of the intracranial biomechanical properties of the subjects.