QUANTITATIVE ASSESSMENT OF IRON OVERLOAD BY MRI

描述 (改编自申请人的摘要)本提案的长期目标 是发展体内磁共振(MR)技术的可靠途径 无创性评估铁超载患者的铁储备 地中海贫血、镰状细胞等疾病的慢性输血治疗 疾病和其他血液疾病。该项目的具体目标是： 1)研究体内铁超载条件下肝组织的T2 并与活检确定的铁水平相关；1b)测量T2 人尸检心脏组织和铁负荷沙土鼠模型 并与化学确定的铁水平相关；2)评估 一种新的、非侵入性的磁化率测量技术 接触参考法，适用于外心肌；(3) 发展一种非侵入性的肝脏敏感性测量技术 使用血管信号作为内部参照物。对…的准确评估 身体铁储备在管理中发挥着核心作用 长期输血的患者。目前的身体铁质评估方法有 仅限于肝脏活检或超导量子干涉装置 (鱿鱼)感光法，但两者都不便于常规使用，而且有 没有非侵入性的技术来评估心脏。这件事的重点是 应用中心是开发肝脏检查技术，以及 铁超载条件下心脏组织磁共振特性的研究。 将使用最小TE为1.5毫秒的光谱序列来测量 30例患者的3x3x3 cm~3体积的肝脏T2，并将结果相互关联 用活检法测定9例人类108例标本中的铁水平 尸检心脏和来自48个沙土鼠心脏的192个标本将被测量和 与组织铁水平相关。原子核的磁化率 同样的人类尸检心脏和沙鼠心脏将通过接触进行评估 参考技术：不同频率的共振频率差 组织和生理盐水参照物的界面，通过使用三维 梯度回波成像，将被用来确定组织敏感性。 最后，一种活体肝脏敏感性测量技术将是 开发：序列二维导航仪回波成像将用于 测量频率偏移时，肝脏的磁化率会 获得。对于每个目标，使用线性回归的统计分析将 以评估MR预测的铁水平的可靠性 技术。

DESCRIPTION (Adapted from applicant's abstract) The long-term objective of this proposal is to develop in vivo magnetic resonance (MR) techniques for a reliable non-invasive assessment of iron stores in patients with iron overload due to chronic transfusion therapy for diseases such as thalassemia, sickle cell disease and other blood disorders. The specific aims of the project are: 1a) to study the T2 of liver tissue under iron overload conditions in vivo and correlate with biopsy determined iron level; 1b) to measure T2 of cardiac tissue from autopsied human hearts and an iron overload gerbil model in vitro and correlate with a chemically determined iron level; 2) to assess a new, non-invasive magnetic susceptibility measurement technique, "the contact reference method," that will be applicable for outer myocardium; (3) to develop a non-invasive susceptibility measurement technique for the liver using blood vessel signal as internal reference. An accurate assessment of body iron stores plays a central role in the management of chronically-transfused patients. Current body iron assessment methods are limited to liver biopsy or superconducting quantum interference device (SQUID) susceptometry, but neither is convenient for routine use, and there is no non-invasive technique to evaluate the heart. The focus of this application centers on developing techniques for the liver examination, and characterizing MR properties of heart tissue under iron overload conditions. A spectroscopy sequence with minimum TE 1.5 ms will be used to measure the liver T2 in a 3x3x3 cm3 volume in 30 patients, and correlate the results with biopsy determine iron level; In vitro T2 of 108 specimens from 9 human autopsy hearts and 192 specimens from 48 gerbil hearts will be measured and correlated with the tissue iron level. The magnetic susceptibility of the same human autopsy hearts and gerbil hearts will be evaluated by a contact reference technique: the resonant frequency differences across the interface of tissue and saline reference, obtained by using 3-dimensional gradient echo imaging, will be used to qualify the tissue susceptibility. Finally, an in vivo liver susceptibility measurement technique will be developed: sequential 2-dimensional navigator echo imaging will be used to measure frequency offset, the magnetic susceptibility of the liver will be obtained. For each aim, statistical analysis using linear regression will be done to assess the reliability of iron level predicted by the MR technique.