Analyses of gradient echo MRI data

描述(由申请人提供)：这项研究的目标是开发对梯度回波(GRE)MRI数据的新分析，以定量描述内在组织特性。梯度回波MRI已被常规应用于临床实践。其图像对比度的一个主要方面是基于其对组织敏感性的独特信号敏感性，这对于研究血液脱氧血红蛋白(fMRI的基础)和血液分解产物、高铁血红蛋白、含铁血黄素和铁蛋白(各种出血性疾病，包括创伤性脑损伤、出血和微出血、血管疾病、神经退行性疾病等)特别有用。例如，GRE MRI正在取代CT成为测量急性脑出血(ICH)的一种方法。然而，众所周知，GRE MRI存在大量敏感伪影，难以识别血肿的真实边界，并高估血肿体积，这是治疗脑出血患者的关键参数。我们假设，对GRE MRI数据的严格分析可以准确地定位易感性源，从而能够可靠地识别血肿量。绘制组织敏感性图需要解决场到源的逆问题，而仅使用相位数据是不适定的。我们提出了一种新的支持形态的偶极子反转(MEDI)方法，用于分析相位和幅度数据梯度回波MRI，以提取组织的敏感度。相图包含了通过麦克斯韦方程拟合磁化率所需的磁场信息。幅度图像包含用于通过最小不一致性与敏感性界面匹配的组织结构信息。我们已经从数学上证明了这些相位和幅度信息足以确定磁化率。我们已经获得了非常令人鼓舞的初步数据，表明我们的MEDI逆方法在解决场源逆问题方面足够准确。因此，我们提出的研究包括以下具体目标。1)发展了分析梯度回波MRI相位和幅度数据的MEDI方法。2)应用MEDI对原发性脑出血患者的梯度回波MRI测量血肿进行分析，并与CT进行比较。

DESCRIPTION (provided by applicant): The objective of this research is to develop novel analyses of the gradient echo (GRE) MRI data for quantitative characterization of intrinsic tissue property. Gradient echo MRI has been routinely used in clinical practice. A major aspect of its image contrast is based on its unique signal sensitivity to tissue susceptibility, which is particularly useful for studying blood deoxyhemoglobin (foundation of fMRI) and blood breakdown products, methemoglobin, hemosiderin and ferritin (various bleeding disorders including traumatic brain injury, hemorrhage and microbleed, vascular disorders, neurodegenerative diseases, et al) that have strong susceptibilities. For example, GRE MRI is becoming a method replacing CT for measuring acute intracerebral hemorrhage (ICH). However, GRE MRI is well known to have blooming susceptibility artifacts that make it difficult to identify the true boundary of hematoma and overestimate hematoma volume, a critical parameter in managing ICH patients. We hypothesize that rigorous analysis of GRE MRI data can allow accurate mapping of susceptibility source, enabling robust identification of hematoma volume. Mapping tissue susceptibility requires solving the field-to-source inverse problem, which is ill-posed using the phase data alone. We propose to develop a novel morphology enabled dipole inversion (MEDI) approach for analyzing both phase and magnitude data gradient echo MRI to extract tissue susceptibility quantity. The phase image contains the magnetic field information for fitting susceptibility via Maxwell's Equation. The magnitude image contains tissue structure information for matching with susceptibility interfaces via least discordance. We have proved mathematically that these phase and magnitude information are sufficient to determine susceptibility. We have obtained very encouraging preliminary data indicating that our MEDI inverse approach is sufficiently accurate in solving the field to source inverse problem. Accordingly, our proposed research consists of the following specific aims. 1) Develop the MEDI approach for analyzing phase and magnitude data in gradient echo MRI. 2) Apply MEDI to analyze gradient echo MRI of patients with primary ICH for measuring hematoma by comparing with CT.