Short Axis EPI for Diffusion Tensor MRI at High Field

用于高场弥散张量 MRI 的短轴 EPI

• 批准号: 7507451
• 负责人: ROLAND BAMMER
• 金额: $ 61.63万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-15 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7507451
• 关键词: Adult; Algorithms; Anatomy; Anesthesia procedures; Attention; Base Sequence; Brain; Cellular Structures; Child; Childhood; Clinical; Clinical Protocols; Communities; Data; Deposition; Development; Diagnosis; Diffuse; Diffusion; Diffusion Magnetic Resonance Imaging; Disease; Early treatment; Enrollment; Environment; Erythrocyte Ghost; Family; Functional Magnetic Resonance Imaging; Functional disorder; Future; Goals; Head; Human; Image; Imaging Techniques; Immune; Immunity; Invasive; Investigation; Lead; Magnetic Resonance Imaging; Maps; Measures; Methodology; Methods; Metric; Modeling; Morphologic artifacts; Motion; Motivation; Myelin Sheath; Neurosciences; Neurosciences Research; Numbers; Outcome; Pathway interactions; Patients; Performance; Population; Preparation; Protocols documentation; Proxy; Research; Resolution; Sampling; Scanning; Scheme; Sedation procedure; Speed; Techniques; Technology; Testing; Time; Tissues; Ursidae Family; Variant; Work; base; design; experience; image reconstruction; improved; infancy; innovation; insight; interest; magnetic field; neuroimaging; novel; programs; reconstruction; relating to nervous system; simulation; size; success; tumor; water diffusion; white matter

DESCRIPTION (provided by applicant): MOTIVATION - Diffusion Tensor Imaging (DTI) is an MRI method for noninvasive quantitative mapping of anisotropic water diffusion, thereby allowing the investigation of white matter (WM) microstructure. DTI holds tremendous potential for aiding the understanding of pathophysiologies of white matter and delayed maturation. In addition, it enables non-invasive tracing of WM pathways in tumor patients and is also helpful for diagnosing patients harboring non-focal disease. However, DTI still suffers from technical shortcomings which become even more problematic with increasing magnetic fields. This is unfortunate since increased magnetic field strengths offer substantially more SNR that is desperately needed for an SNR-starved method such as DTI. Because of their size and other specific requirements, especially pediatric patients would be major benefactors from DTI high field imaging - particularly when combined with more powerful fMRI and structural imaging achievable at these higher fields. Obstacles to using DTI at higher fields include: FOV requirements, lack of cooperation, increased motion, increase off-resonance artifacts, significant RF inhomogeneity, and increased RF energy deposition. AIMS - The main objective of the proposed project is to create significant improvements in DTI at high field (i.e. 3T and 7T) via novel acquisition/reconstruction techniques that reduce distortions, improve immunity to motion, diminish RF deposition and flip angle variation, and provide better spatial resolution so that improved pediatric and adult high-field DTI is enabled. The specific aims are to develop and optimize acquisition and reconstruction methods for diffusion tensor short-axis-readout EPI (sr-EPI) (A.1), and investigate and help to rekindle interest in 7T DTI by incorporating optimized sr-EPI DTI sampling strategies with parallel transmit as well as to further boost scan efficiency by adding multi-echo readouts (A.2). Anticipating the move toward higher-field strengths, these aims are designed to provide a robust imaging protocol for the clinical environment (3T), while providing the means to overcome short-comings in current ultra-high field strength methodologies. METHODS - In A.1, novel schemes for off-resonance, eddy-current, and motion correction will be developed. In addition, an efficient parallel imaging reconstruction algorithm will be developed to compliment a family of proposed SNR-, SAR-, and scan time-efficient sr-EPI techniques. In A.2, work with an experienced group of collaborators will allow the implementation of parallel transmit technology on our 7T. Together with an 'exact' distortion model, these B1/B0 correction methodologies ideally compliment a fast variant of sr-EPI. By adding RF-refocused multi-blade/blind readout the scan efficiency will be increased even further. All proposed acquisition and reconstruction techniques will be optimized both in simulations and phantom studies. A total number of subjects of 200 (children and adults) will be enrolled over this five year period for extensive testing. Optimal image quality will be determined by quantitative metrics and human observers. SIGNIFICANCE -We believe successful attainment of these aims promises to significant improvements in DTI, reaching beyond high field and pediatric patients, and hence greater overall utility of DTI. Abnormalities in WM and tract projections could provide crucial insights in the pathophysiology of several diseases that attack white matter, and further the understanding of specific neurodevelopmental trajectories of children with and without WM disorders. The success of our research effort would be of great value since it would build the basic methodological framework at high field for further clinically focused studies and basic neuroscience research.

描述（由申请人提供）：动机-扩散张量成像（DTI）是一种非侵入性定量测绘各向异性水扩散的MRI方法，从而允许研究白质（WM）微观结构。DTI在帮助理解白质和延迟成熟的病理生理方面具有巨大的潜力。此外，它可以无创地追踪肿瘤患者的WM通路，也有助于诊断患有非局灶性疾病的患者。然而，DTI仍然存在技术缺陷，随着磁场的增加，这些缺陷变得更加成问题。这是不幸的，因为增加的磁场强度提供了更多的信噪比，这对于像DTI这样的信噪比匮乏的方法来说是迫切需要的。由于它们的尺寸和其他特殊要求，特别是儿科患者将是DTI高场成像的主要受益者-特别是当与更强大的fMRI和结构成像相结合时，这些高场成像可以实现。在更高的领域使用DTI的障碍包括：视场要求、缺乏合作、运动增加、非共振伪影增加、显著的射频不均匀性和增加的射频能量沉积。目标-拟议项目的主要目标是通过新颖的采集/重建技术来显著改善高视场（即3T和7T）的DTI，减少扭曲，提高对运动的免疫，减少RF沉积和翻转角度变化，并提供更好的空间分辨率，从而改善儿童和成人的高视场DTI。具体目标是开发和优化扩散张量短轴读出EPI (sr-EPI) （A.1）的采集和重建方法，并通过将优化的sr-EPI DTI采样策略与并行传输相结合，以及通过增加多回波读出进一步提高扫描效率（A.2）来研究并帮助重新激发对7T DTI的兴趣。这些目标旨在为临床环境（3T）提供强大的成像方案，同时为克服当前超高场强方法的缺点提供手段。方法：在A.1中，将开发非共振、涡流和运动校正的新方案。此外，将开发一种高效的并行成像重建算法，以补充一系列提出的SNR-、SAR-和扫描时效率高的sr-EPI技术。在A.2中，与经验丰富的合作者合作将允许在我们的7T上实现并行传输技术。与“精确”失真模型一起，这些B1/B0校正方法理想地补充了sr-EPI的快速变体。通过增加射频重聚焦多刀片/盲读出，扫描效率将进一步提高。所有提出的采集和重建技术将在模拟和模拟研究中进行优化。总共有200名受试者（儿童和成人）将在这五年的时间里被招募进行广泛的测试。最佳图像质量将由定量指标和人类观察者来确定。