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)

• 批准号: 7362406
• 负责人: Charles A. Mistretta
• 金额: $ 17.64万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 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/7362406
• 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

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，我们的小组研究了与奈奎斯特定理相关的各种形式的 k 空间和时间欠采样，以便在具有挑战性的 MR 成像应用中更快地采集数据，特别是时间分辨、高分辨率对比增强血管造影。使用 3D TRICKS，实现了 3 的时间欠采样因子，以提供时间分辨的 3D MR 血管造影照片。后来，开发了面内径向欠采样采集，用于采集角度欠采样因子为 6 的血管造影照片。PR TRICKS 中这两种技术的组合导致欠采样因子为 18。欠采样通过 VIPR 扩展到真正的 3D 径向轨迹，其中典型的欠采样因子为 50，在某些应用中可以使用而不会产生明显的伪影。此外，VIPR 与相衬成像相结合，可以在大体积内进行 3D 流量测量，从而推导小血管中的压力梯度。 最近，我们开发了一种称为 HYPR（高度约束反投影）的近似非迭代重建技术的概念，以通过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的重要因素进一步增加时间演变采集的允许欠采样。初步结果表明，对比增强血管造影的欠采样系数在 100 到 300 之间。在 4 分钟的 3843 时间分辨相位对比检查中，在足够的 SNR 下实现了接近 1000 的系数，而使用传统的笛卡尔相位编码方法则需要 39 小时。该技术还用于实现 X 射线 CT 灌注剂量减少 10 倍，并且可以推广到其他图像系列应用，例如 MR 扩散张量成像，其中该技术使用一系列具有不同扩散编码方向的图像在 2D 实现中模拟 15 倍欠采样。此处未提出的大量其他潜在应用将受益于对所提出的算法及其潜在局限性的更好理解。 HYPR 通过将长合成图像中获得的 SNR 转移到单独的时间帧中来提供独特的 SNR 行为。必须针对每个临床应用调整该合成图像的持续时间，以便最大限度地减少空间模糊和波形失真。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模型来研究 HYPR 的基本特性，并进行三项初步的患者研究，以确定用于未来验证研究的方案。该提案的重点是使用 PR HYPR TRICKS 和 HYPR VIPR 评估脑 AVM，以及测量狭窄颈动脉的压力梯度。

项目成果

Ultrashort TE spectroscopic imaging (UTESI) using complex highly-constrained backprojection with local reconstruction (HYPR LR).

使用复杂的高度约束反投影和局部重建 (HYPR LR) 的超短 TE 光谱成像 (UTESI)。

• DOI: 10.1002/mrm.21986
• 发表时间: 2009
• 期刊: Magnetic resonance in medicine
• 影响因子: 3.3
• 作者: Wang,Kang;Du,Jiang;O'Halloran,Rafael;Fain,Sean;Kecskemeti,Steven;Wieben,Oliver;Johnson,KevinM;Mistretta,Charles
• 通讯作者: Mistretta,Charles