QUANTITATIVE SODIUM MRI AT 7T WITH 12 CHANNEL PHASED-ARRAY COIL

使用 12 通道相控阵线圈进行 7T 定量钠 MRI

• 批准号: 8361983
• 负责人: David Pilkinton
• 金额: $ 1.54万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8361983
• 关键词: Concentration measurement; Dimensions; Fourier Transform; Funding; Grant; Image; Magnetic Resonance; Magnetic Resonance Imaging; Maps; Measurement; Measures; Methods; National Center for Research Resources; Noise; Phase; Principal Investigator; Radial; Relaxation; Research; Research Infrastructure; Resources; Signal Transduction; Sodium; Source; Techniques; Time; Tissues; United States National Institutes of Health; Weight; cost; optical imaging

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. To maximize signal-to-noise ratio (SNR) and minimize relaxation weighting, ultra-short echo (UTE) readouts have been generally been favored for sodium MRI. UTE methods have also been used to measure total sodium concentration (TSC) in tissues, although this typically requires accurate mapping of the B1 field. B1 measurements are typically noisy and error prone, making good TSC measurements difficult unless the B1 is highly homogeneous. The multi-channel phase coils that are preferred in sodium MRI studies because of the increase SNR are more inhomogeneous that birdcage coils, making good B1 measurement important in most sodium MRI applications. UTE methods also suffer from off-resonance and T2*-associated blurring in the readout direction, further making quantitative measurements with these techniques difficult. A more reliable quantitative parameter for sodium MRI is the measurement of the long component of the transverse relaxation time, T2L*. By collecting several echoes after the short transverse relaxation component has decayed, the resulting decay curve can be accurately fitted to a monoexponential curve. UTE methods typically use a radial or spiral readout in two or three- dimensions, followed by gridding onto Cartesian k-space before Fourier transforming to image space. We have found that we can obtain very similar results using an acquisition weighted half-echo readout directly on a Cartesian grid. We then followed this half-echo readout with five full-echo standard Cartesian readouts. This imaging sequence has the benefit of producing an image with the highest possible SNR and lowest possible relaxation weighting while also providing a robust quantitative parameter.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的主要研究者可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 为了最大化信噪比 (SNR) 并最小化弛豫加权，超短回波 (UTE) 钠 MRI 读数通常受到青睐。 UTE方法也被用于 测量组织中的总钠浓度 (TSC)，尽管这通常需要准确的 B1 字段的映射。 B1 测量通常有噪声且容易出错，因此 TSC 良好 除非 B1 高度均匀，否则测量很困难。 多通道相线圈 在钠 MRI 研究中是首选，因为 SNR 的增加更加不均匀 鸟笼线圈，使得良好的 B1 测量在大多数钠 MRI 应用中非常重要。 UTE 方法还受到读出方向上的偏共振和 T2* 相关模糊的影响， 进一步使得使用这些技术进行定量测量变得困难。 更可靠的 钠 MRI 的定量参数是对钠 MRI 的长分量的测量 横向弛豫时间，T2L*。 通过收集短横向后的多个回波 弛豫分量已经衰减，所得到的衰减曲线可以准确地拟合到 单指数曲线。 UTE 方法通常使用两个或三个径向或螺旋读数 尺寸，然后在傅立叶变换为图像之前网格化到笛卡尔 k 空间 空间。 我们发现使用采集加权可以获得非常相似的结果 直接在笛卡尔网格上进行半回波读数。 然后我们按照这个半回波读数 五个全回波标准笛卡尔读数。 该成像序列的优点是产生 具有尽可能高的信噪比和尽可能低的松弛权重的图像，同时还 提供稳健的定量参数。