HighlY constrained backPRojection (HYPR) for Ultrafast Undersampled MRI

用于超快欠采样 MRI 的高度约束反投影 (HYPR)

基本信息

批准号：
7258172
负责人：
Charles A. Mistretta
金额：
$ 21.67万
依托单位：
UNIVERSITY OF WISCONSIN-MADISON
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-03-01 至 2009-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7258172
关键词：
A-factor (Streptomyces)Algorithms Angiography Back Behavior Blur Carotid Arteries Cerebrum Computer Simulation Condition Contracts Data Set Derivation procedure Diffusion Diffusion Magnetic Resonance Imaging Dose Equation Evaluation Future Generations Grant Hour Hybrids Image Imaging Techniques Individual Magnetic Resonance Imaging Maps Measurement Measures Methods Morphologic artifacts Motion Numbers Patients Performance Perfusion Phase Process Property Protocols documentation Radial Rate Relative (related person)Resolution Sampling Scanning Series Simulate Slice Standards of Weights and Measures Stenosis Techniques Time Tornadoes Venous Malformation Work X-Ray Computed Tomography base clinical application cohort concept in vivo pressure reconstruction research study simulation size validation studies

A-factor (Streptomyces)Algorithms Angiography Back Behavior Blur Carotid Arteries Cerebrum Computer Simulation Condition Contracts Data Set Derivation procedure Diffusion Diffusion Magnetic Resonance Imaging Dose Equation Evaluation Future Generations Grant Hour Hybrids Image Imaging Techniques Individual Magnetic Resonance Imaging Maps Measurement Measures Methods Morphologic artifacts Motion Numbers Patients Performance Perfusion Phase Process Property Protocols documentation Radial Rate Relative (related person)Resolution Sampling Scanning Series Simulate Slice Standards of Weights and Measures Stenosis Techniques Time Tornadoes Venous Malformation Work X-Ray Computed Tomography base clinical application cohort concept in vivo pressure reconstruction research study simulation size validation studies

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项目摘要

DESCRIPTION (provided by applicant): During the past nine years our group has investigated various forms of k-space and temporal undersampling relative to the Nyquist Theorem for faster acquisitions in challenging MR imaging applications, particularly time resolved, high resolution contrast-enhanced angiography. Using 3D TRICKS, a temporal undersampling factor of 3 was achieved to provide time resolved 3D MR angiograms. Later, in-plane radially undersampled acquisitions were developed for acquiring angiograms with angular undersampling factors of 6. The combination of these two techniques in PR TRICKS resulted in undersampling factors of 18. Undersampling was extended to a truly 3D radial trajectory with VIPR, where typical undersampling factors of 50 can be used without significant artifacts in certain applications. In addition, VIPR has been combined with phase contrast imaging to permit 3D flow measurements across a large volume enabling the derivation of pressure gradients in small vessels. Recently, we developed the concept for an approximate non-iterative reconstruction technique called HYPR (HighlY constrained back PRojection) to further increase the permissible undersampling of temporally evolving acquisitions by another large factor that depends on the sparsity of the data set and the degree of spatio- temporal correlation between the serial images. Preliminary results have produced undersampling factors between 100 and 300 for contrast-enhanced angiography. A factor of nearly 1000 was achieved with adequate SNR in a 4 minute 3843 time-resolved phase contrast examination that would have required 39 hours using conventional Cartesian phase encoding methods. The technique was also used to achieve a factor of ten dose reduction in X-ray CT perfusion and can be generalized to other image series applications such as MR diffusion tensor imaging where the technique has simulated a factor of 15 undersampling in a 2D implementation using a series of images having different diffusion encoding directions. A large number of other potential applications that are not proposed here will benefit from a better understanding of the proposed algorithm and its potential limitations. HYPR provides unique SNR behavior by transferring the SNR obtained in a long composite image into individual time frames. The duration of this composite image must be adjusted for each clinical application so that spatial blurring and waveform distortion can be minimized. This depends on sparsity and spatio-temporal correlation conditions. We propose to investigate the basic properties of HYPR using computer simulations and phantoms and to conduct three preliminary patient studies to establish protocols to be used in future validation studies. This proposal focuses on the evaluation of cerebral AVMs using PR HYPR TRICKS and HYPR VIPR and the measurement of pressure gradients across stenotic carotid arteries.

描述（由申请人提供）：在过去的九年中，我们的小组研究了各种形式的K空间和时间底采样，相对于Nyquist定理，在挑战MR成像应用方面进行了更快的获取，尤其是时间解决，尤其是时间解决，高分辨率对比度增强血管造影。使用3D技巧，实现了3D的时间下采样系数，以提供时间分解的3D MR血管造影。后来，开发了平面内径向不足的采集，以获取具有角度下采样因子6的血管造影。这两种技术在公关技巧中的组合导致18的底采样因子18。无效采样扩展到具有典型的耐心范围的50个典型范围内的3D轨迹，而不必使用一定的vipr，则可以进行50个典型的处理。此外，VIPR已与相对比成像结合使用，以允许在大容量的大容量上进行3D流量测量，从而实现了小容器中压力梯度的推导。最近，我们为一种称为HYPR（高度约束的背部投影）的近似非著作重建技术开发了该概念，以进一步增加了允许的允许的允许的不变采样，这取决于另一个取决于数据集的稀疏性和串行图像之间的时空相关程度。对比增强血管造影的初步结果产生了100至300之间的不足采样因子。在4分钟的3843个时间分辨相对比检查中，使用足够的SNR实现了近1000倍，使用常规的笛卡尔相对比检查将需要39小时。该技术还用于实现X射线CT灌注的十倍降低剂量，并可以推广到其他图像系列应用，例如MR扩散量张量成像，其中该技术使用具有不同扩散的编码方向的一系列图像模拟了2D实施中的15倍。此处未提出的许多其他潜在应用将受益于对拟议算法及其潜在局限性的更好理解。 HYPR通过将在长复合图像中获得的SNR转移到单个时间范围中，从而提供了独特的SNR行为。必须针对每个临床应用调整此复合图像的持续时间，以便可以将空间模糊和波形失真最小化。这取决于稀疏性和时空相关条件。我们建议使用计算机模拟和幻影研究HYPR的基本特性，并进行三项初步的患者研究，以建立在将来的验证研究中使用的方案。该提案的重点是使用PR HYPR技巧和HYPR VIPR评估脑AVM，以及跨狭窄颈动脉的压力梯度的测量。