Analyses of gradient echo MRI data

描述（由申请人提供）：本研究的目的是开发梯度回波（GRE） MRI数据的新分析，用于定量表征组织特性。梯度回声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易感性的独特信号敏感性，这对于研究具有强易感性的血液脱氧血红蛋白（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成为急性脑出血（ICH）的检测方法。然而，众所周知，GRE MRI具有明显的敏感性伪影，这使得难以识别血肿的真实边界和高估血肿体积，而血肿体积是管理脑出血患者的关键参数。我们假设对GRE MRI数据进行严格的分析可以精确地绘制敏感性来源，从而能够可靠地识别血肿体积。绘制组织磁化率需要解决场源反问题，这是仅使用相位数据的不适定问题。我们提出了一种新的形态偶极子反演（MEDI）方法，用于分析相位和幅度数据梯度回波MRI以提取组织敏感性数量。相位图像包含磁场信息，通过麦克斯韦方程拟合磁化率。图像中包含组织结构信息，通过最小不一致性与敏感界面匹配。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反演方法在解决场源反演问题方面是足够准确的。因此，我们提出的研究包括以下具体目标。1)发展梯度回波MRI相位和震级数据的MEDI分析方法。2)应用MEDI分析原发性脑出血患者的梯度回声MRI测量血肿，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.