Development of a novel single-scan acquisition and model-based reconstruction method for fast, accurate and robust multi-parametric quantitative MRI at ultrahigh field strength

定量磁共振成像（qMRI）允许测量大量的生理磁共振参数。其中，以下参数被认为是重要的，因为它们已知受到几种神经病理学的影响：含水量、纵向松弛时间T1、有效横向松弛时间T2*、磁化率和电导率。用于测量这些参数的传统方法要么采集时间长，对患者运动敏感，影响其临床适用性，要么容易受到磁场不均匀性的影响，比吸收率高，影响其在超高场强下的应用。本项目的目的是开发一种新的qMRI方法来同时绘制上述参数，该方法具有快速，准确和运动鲁棒性，同时对磁场不均匀性具有鲁棒性，并且具有低比吸收率。这使得它既适用于临床，也非常适合在超高场强下应用。该方法由一种新的MR序列和一种新的图像重建技术组成，可以在5-7分钟的采集时间内生成数百张具有1mm各向同性分辨率和全脑覆盖的对比度图像。这些图像是在不同的回波和反演时间获得的，并构成后续定量参数映射的基础。

Quantitative magnetic resonance imaging (qMRI) allows a multitude of physiological MR parameters to be measured. Among those, the following parameters are considered significant as they are known to be affected by several neurological pathologies: water content, longitudinal relaxation time T1, effective transverse relaxation time T2*, magnetic susceptibility, and electric conductivity. Conventional methods which can be used to measure these parameters either suffer from long acquisition times and are sensitive to patient motion, tarnishing their clinical applicability, or are susceptible to magnetic field inhomogeneity and have a high specific absorption rate, which impairs their application at ultrahigh field strength. The aim of this project is to develop a novel qMRI method to simultaneously map the aforementioned parameters, which is designed to be fast, accurate, and motion-robust, while simultaneously being robust against magnetic field inhomogeneity and having a low specific absorption rate. This makes it both clinically applicable and also well suited for application at ultrahigh field strength. The proposed method consists of a new MR sequence and a new image reconstruction technique to produce hundreds of contrast images with 1mm isotropic resolution and full brain coverage within only 5-7 minutes of acquisition time. These images are acquired at different echo and inversion times and form the basis of the subsequent quantitative parametric mapping.