Modified Elliptical Centric View Orders for Improved Real-Time MRA

描述(由申请人提供)：本次拨款申请的总体目的是进一步借鉴上一个资金周期在对比增强磁共振血管成像(CE-MRA)方面取得的广泛进展，并将该领域推向更高的水平。在过去的几年里，CE-MRA取得了多项进展，我们相信我们自己的团队的工作对此做出了实质性的贡献。具体进展包括：(I)将2D并行采集应用于椭圆中心CE-MRA时信号增强效果的演示；(Ii)加速CE-MRA中改进的血管锐度的演示；(Iii)用于时间分辨CE-MRA的笛卡尔采集和投影重建类采样(CAPR)脉冲序列的开发；(Iv)CE-MRA中超过10的加速因子的常规演示；(V)用于加速CE-MRA的模块化线圈阵列的开发；(V)证明CAPR在描述动态现象方面提供高保真；以及(Vi)高质量时间分辨率3DCE-MR脑和小腿血管成像的常规演示。具体研究目标有：1.高质量的综合神经血管检查。在20-23年工作的延伸中，我们将在一次全面的检查中生成高质量的主动脉弓、颈动脉、颅内动脉和脑部引流静脉的图像。用于评估2D切片计时的传统测试推注将被低剂量(1-2毫升)3D时间分辨CE-MRA序列所取代。这之后将是正常剂量(18毫升)采集，其中多元素、模块化射频线圈阵列将允许2D加速采集，为所有地区提供高空间分辨率数据集。。上肢和腹部的高分辨率CAPR以前开发的用于大脑和小腿磁共振血管成像的并行采集技术将适用于其他解剖区域。对于每个区域，模块线圈阵列元素将与特定的视场(FOV)和所需的空间分辨率相匹配。对于手，视野通常是不对称的(L/R与A/P)，这表明对于小腿，使用不同大小的元素。对于腹部，增加的视野需要更大的线圈元件。3.血管造影术与磁共振灌注成像相结合。对CAPR CE-MRA脑研究中脑实质信号水平的分析表明，可以检测到首次通过的脑实质“脸红”，这表明从血管造影数据集提供血流灌注信息的潜力。然而，这可能会受到帧时间仍然略长和信噪比略小的限制。为了解决这一问题，我们将调整基本的CAPR序列，以使用十倍或更高的2D感测加速系数来提高时间分辨率。为了保持信噪比，特别是在实质信号中，我们将应用最近开发的压缩传感方法。1

DESCRIPTION (provided by applicant): The overall purpose of this grant application is to further draw on the extensive developments made in contrast-enhanced MR angiography (CE-MRA) during the previous funding cycle and push the field to even higher levels. The last several years have seen multiple developments in CE-MRA, and we believe that the work of our own group has contributed materially to this. Specific developments include: (i) demonstration of a signal enhancement effect when 2D parallel acquisition is applied to elliptical centric CE-MRA; (ii) demonstration of improved vessel sharpness in accelerated CE-MRA; (iii) development of the Cartesian Acquisition with Projection-Reconstruction-like sampling (CAPR) pulse sequence for time-resolved CE-MRA; (iv) routine demonstration of acceleration factors exceeding 10 in CE-MRA; (v) development of modular coil arrays for accelerated CE-MRA; (v) demonstration that CAPR provides high fidelity in the portrayal of dynamic phenomena; and (vi) routine demonstration of high quality time-resolved 3D CE-MR angiograms of the brain and calves. Specific aims to be studied are: 1. High Quality Comprehensive Neurovascular Exam. In an extension of the work performed during Years 20- 23 we will generate high quality images of the vasculature of the aortic arch, carotid arteries, intracranial arteries, and the draining veins of he brain in one comprehensive exam. The traditional test bolus used to assess timing in a 2D slice will be replaced with a low dose (1-2 ml) 3D time-resolved CE-MRA sequence. This will be followed by normal dose (18 ml) acquisition in which multi-element, modular RF coil arrays will allow 2D accelerated acquisition, providing high spatial resolution data sets for all territories. . High Resolution CAPR of the Upper Extremities and Abdomen. Parallel acquisition techniques previously developed for MR angiography of the brain and calves will be adapted to other anatomic regions. For each region the modular coil array elements will be matched to the specific field-of-view (FOV) and desired spatial resolution. For the hands the FOV is typically asymmetric (L/R vs. A/P), suggesting that elements having different sizes be used as for the calves. For the abdomen the increased FOV calls for larger coil elements. 3. Combined Angiographic and Perfusion MR Imaging. Analysis of the signal levels in brain parenchyma from CAPR CE-MRA studies of the brain has shown that first-pass parenchymal "blush" is detectable, suggesting the potential for providing perfusion information from the angiographic data set. However, this can be limited by a frame time which is still marginally too long and SNR which is marginally too small. To address this we will adapt the basic CAPR sequence for improved temporal resolution using 2D SENSE acceleration factors of ten-fold and higher. To retain SNR, particularly within the parenchymal signal, we will apply recently developed compressive sensing methods. 1