Novel Acquisition Methods for Diffusion MRI

扩散 MRI 的新采集方法

• 批准号: 7837741
• 负责人: ROLAND BAMMER
• 金额: $ 40万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7837741
• 关键词: Adult; Algorithms; Anatomy; Anesthesia procedures; Attention; Autistic Disorder; Awareness; Cellular Structures; Child; Childhood; Clinical; Communities; Complex; Data; Databases; Dependence; Deposition; Development; Diagnosis; Diagnostic; Diagnostic Procedure; Diffuse; Diffusion; Diffusion Magnetic Resonance Imaging; Diffusion weighted imaging; Disease; Early treatment; Elements; Enrollment; Entropy; Evaluation; Fiber; Frequencies; Functional Magnetic Resonance Imaging; Functional disorder; Future; Goals; Guidelines; Hand; Head; Hybrids; Image; Imaging Techniques; Immune; Immunity; Investigation; Knowledge; Lead; Magnetic Resonance Imaging; Maps; Measures; Memory; Methods; Modification; Morphologic artifacts; Motion; Myelin Sheath; Neurosciences; Noise; Outcome; Pathologic; Pathway interactions; Patients; Performance; Phase; Physiologic pulse; Physiological; Population; Process; Protocols documentation; Protons; Proxy; Qualifying; Real-Time Systems; Registries; Reliance; Research; Research Personnel; Resolution; Scanning; Scheme; Sedation procedure; Signal Transduction; Speed; Techniques; Testing; Time; Tissues; Variant; Weight; absorption; base; clinical application; clinical practice; combat; comparative; compliance behavior; data space; experience; image reconstruction; imaging modality; improved; infancy; innovation; insight; magnetic field; migration; neuroimaging; novel; prospective; reconstruction; relating to nervous system; simulation; tumor; water diffusion; white matter

MOTIVIATION - One of MRI’s inherent biophysical contrast parameters is proton self-diffusion, which can be measured by diffusion-weighted imaging (DWI). A variant, Diffusion Tensor Imaging (DTI), is an MRI method for noninvasive quantitative mapping of anisotropic water diffusion, thereby allowing the non-invasive investigation of white matter (WM) microstructure which might aid in the diagnosis and understanding the pathophysiology of white matter abnormalities and delayed maturation. DTI has been also used extensively for non-invasive tracing of WM pathways in tumor patients and in patients harboring non-focal disease. Unfortunately, DTI still suffers not only from physiologic motion but also from profound technical difficulties that increase with higher magnetic fields; higher magnetic fields on the other hand would offer substantially more signal-to-noise ratio (SNR). One of the major benefactors from motion-compensated DTI at high field would be children because of their smaller head sizes and the higher likelihood of motion. AIMS - The overarching goal of this 2-year research effort is to improve diffusion-weighted multi-shot spiral imaging to create significant improvements in 2D and 3D diffusion tensor imaging. Specifically, the project focuses on improvements for spiral acquisition methods and corresponding reconstruction techniques that reduce distortions, improve immunity to motion, diminish RF deposition, and provide better spatial resolution. Special emphasis is also given on improving image quality of this sequence for pediatric imaging. The specific aims are: (Specific Aim #1) to develop and optimize acquisition and reconstruction methods for real-time spiral diffusion-weighted MRI for 2D and 3D acquisitions; (Specific Aim #2) to define optimal DTI scan parameters for 2D and 3D for adults and children at 3T and 7T for different clinical applications and variants of motion. METHODS - Navigator, (prospective and retrospective) motion and off-resonance correction schemes in concert with augmented parallel imaging reconstruction algorithms will be developed and optimized both in simulations and phantom studies. Healthy children (n=62) and adults (n=30) will be enrolled for extensive testing. Optimal DTI scan parameters for a battery of different clinical questions and variants of motion will be determined by experienced neuroimagers and neuroradiologists. The raw k-space data and high-resolution diffusion tensor data will be added to a registry and can be made available to the public to improve image reconstruction algorithms (e.g. off-resonance correction, parallel imaging, diffusion phase navigation, gridding reconstruction), tensor processing (e.g. studying partial volume effects, crossing fibers, complex tract tracing algorithms) and to provide a normative database for adults and children that can be used in future trials. SIGNIFICANCE –We believe that upon successful completion of this project significant improvements in DTI can be achieved that will improve morphometric assessment and tract tracing in patients harboring various pathologic conditions. 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.

动机：MRI固有的生物物理对比参数之一是质子自扩散，这可以通过扩散加权成像（DWI）来测量。弥散张量成像（DTI）是一种非侵入性定量绘制各向异性水扩散的MRI方法，因此可以对白质（WM）微观结构进行非侵入性研究，这可能有助于诊断和理解白质异常和延迟成熟的病理生理学。DTI也广泛用于肿瘤患者和非局灶性疾病患者的WM通路的无创追踪。不幸的是，DTI不仅受到生理运动的影响，而且还面临着随着磁场的增加而增加的深刻的技术困难；另一方面，更高的磁场会提供更高的信噪比（SNR）。运动补偿DTI的主要受益者之一是儿童，因为他们的头部尺寸较小，运动的可能性更高。AIMS -这项为期2年的研究工作的总体目标是改进扩散加权多镜头螺旋成像，以显著改进2D和3D扩散张量成像。具体而言，该项目侧重于改进螺旋采集方法和相应的重建技术，以减少扭曲，提高运动免疫力，减少射频沉积，并提供更好的空间分辨率。