MRI-based Quantitative Susceptibility Mapping of Hepatic Iron Overload

项目摘要/摘要 这项提案的总体目标是开发和验证一种新的磁共振技术 基于磁共振成像(MRI)的腹部定量敏感性标测(QSM)，用于非侵入性 评估肝脏铁沉积情况。在这项工作中，我们将开发和优化先进的数据采集和 启用腹部QSM的图像重建方法。此外，我们将确定准确度， 腹部QSM测定肝脏铁负荷患者铁含量的重复性和再现性。 铁在包括肝脏在内的各种器官中过度蓄积，这对成人和儿童都有影响 它是有毒的，需要进行旨在减少体内铁储存的治疗。准确评估肝脏 铁浓度对于检测和分期铁超载以及纵向监测是至关重要的 在治疗过程中。 核磁共振是一种广泛可用的技术，对铁的存在高度敏感。不幸的是，目前的核磁共振 弛豫测量方法从根本上受到了它们与铁浓度的关系的鲜为人知的限制， 这取决于铁超载的类型，在治疗过程中也会有所不同。相比之下，核磁共振也是 对组织的磁化率非常敏感，这与铁有众所周知的关系 集中精神。磁化率以一种很好的方式扭曲了主磁场，这 磁场变形可以在活体内测量。基于磁共振成像的QSM方法估计患者的易感性 基于测量组织本身产生的磁场失真的组织。核磁共振- 基于QSM的方法已经开发出来，并在大脑中得到了验证。然而，将QSM翻译为 腹部手术一直没有成功。我们确定了QSM发展的四大技术障碍 腹部：1)腹部脂肪的存在，这会带来额外的相移和 混淆了易感性估计，2)肝脏中铁浓度非常高的可能性(与 大脑)，这导致信号迅速衰减，3)呼吸和其他生理运动，这引入了 获取的图像和估计的磁化率图中的伪影，以及4)最近识别的空间分辨率 当空间分辨率不足时，在QSM中引入偏差的影响。 通过解决这四个障碍，我们将开发一种新的基于MRI的QSM方法，用于 腹部，以量化肝脏铁超载。初步的验证研究是非常有希望的，并表明 为患者LIC的定量提供了极好的前景。在本提案中，我们的目标是[1]完成 基于MRI的腹部QSM的发展，用于测量LIC，[2]确定重复性和 在肝铁超载患者中1.5T和3T QSM的重复性，[3]确定QSM的准确性 超导量子在肝脏铁负荷患者1.5T和3T腹部QSM中的应用 以干扰装置(SQUID)生物磁性肝易感测定仪为参考标准。 综上所述，该项目将开发一种新的基于MRI的QSM技术，用于腹部和 将在患有肝铁超载的儿童和成人患者中进行验证。验证成功后，QSM将 根据组织的基本属性提供准确、可重复和可重现的LIC定量。

PROJECT SUMMARY / ABSTRACT The overall goal of this proposal is to develop and validate a novel technique for Magnetic Resonance Imaging (MRI)-based Quantitative Susceptibility Mapping (QSM) of the abdomen, for non-invasive assessment of liver iron deposition. In this work, we will develop and optimize advanced data acquisition and image reconstruction methods to enable QSM of the abdomen. Further, we will determine the accuracy, repeatability, and reproducibility of abdominal QSM for iron quantification in patients with liver iron overload. Excessive accumulation of iron in various organs, including the liver, which affects both adult and pediatric populations, is toxic and requires treatment aimed at reducing body iron stores. Accurate assessment of liver iron concentration is critical for the detection and staging of iron overload as well as for longitudinal monitoring during treatment. MRI is a widely available technology and highly sensitive to the presence of iron. Unfortunately, current MRI relaxometry methods are fundamentally limited by their poorly understood relationship to iron concentration, which depends on the type of iron overload and also varies during treatment. In contrast, MRI is also exquisitely sensitive to the magnetic susceptibility of tissue, which has a well-understood relationship to iron concentration. Magnetic susceptibility distorts the main magnetic field in a well-characterized manner, and this magnetic field distortion can be measured in-vivo. MRI-based QSM methods estimate the susceptibility of tissues based on measuring the magnetic field distortion produced by the tissues themselves. MRI- based QSM methods have been developed and validated in the brain. However, translation of QSM to the abdomen has been unsuccessful. We have identified four major technical barriers for development of QSM of the abdomen: 1) the presence of fat throughout the abdomen, which introduces additional phase shifts and confounds the susceptibility estimates, 2) the potential for very high iron concentration in the liver (compared to the brain), which results in rapid signal decay, 3) respiratory and other physiological motion, which introduces artifacts in the acquired images and estimated susceptibility maps, and 4) recently identified spatial resolution effects, which introduce bias in QSM when insufficient spatial resolution is acquired. By addressing these four barriers, we will develop a novel MRI-based QSM method for use in the abdomen to quantify liver iron overload. Preliminary validation studies are very promising and have shown excellent promise for the quantification of LIC in patients. In this proposal, we aim to [1] complete development of MRI-based abdominal QSM for measurement of LIC, [2] determine the repeatability and reproducibility of QSM at 1.5T and 3T in patients with liver iron overload, [3] determine the accuracy of abdominal QSM at 1.5T and 3T in patients with liver iron overload using superconducting quantum interference device (SQUID) biomagnetic liver susceptometry as the reference standard. In summary, this project will develop a novel MRI-based QSM technique designed for the abdomen and will validate it in pediatric and adult patients with liver iron overload. Upon successful validation, QSM will provide accurate, repeatable, and reproducible quantification of LIC based on a fundamental property of tissue.