IMPROVED CINE MRI BY DIRECT-INVERSION RECONSTRUCTION

描述(申请人提供)：采集速度仍然是电影磁共振成像(MRI)中的一个关键问题。结构和功能心脏成像，以及越来越多的冠状动脉和血流成像，正在成为评估广泛的心血管疾病的越来越重要的工具。所有这些扫描通常都涉及心脏和呼吸运动的解剖结构。多时相心电门控成像现在通常以屏气模式进行，但患者可以容忍的屏气采集持续时间和次数都是影响图像质量和分辨率的主要限制因素。许多心脏病的特殊症状加剧了这些局限性。人们通过多种方式追求更快的MRI数据采集：改进的梯度硬件允许更快的空间编码；相控阵射频线圈提供更高的信噪比(SNR)；新的稳态自由进动采集技术有助于改进这两方面；其他创新，如部分傅立叶成像、并行成像或缩小视场(RFOV)方法，通过利用成像模型中各种类型的先验知识来探索进一步提高成像速度。结合使用提高信噪比或速度的技术，不断突破电影成像在临床上可行应用的极限。然而，并不是所有的技术都是兼容的，而且从所有单独的技术中获得的收益是有限的，因此在这个领域开发更多的技术仍然是必要的和高度相关的。这项提案将研究一种新的rFOV技术的开发和评估，该技术有望在空间和时间分辨率方面提供比同类方法更重要的优势。该项目建立在回顾实施的令人鼓舞的初步结果的基础上，使用从常规获取的MRI数据中减少的子集来获得全分辨率电影重建。提出了在临床设备上完全前瞻性地实施采办方法的发展。关于SNR、伪影和数值效率的优化将被研究。将使用该方法对图像质量和流量计算进行定性和定量评估。最后，对该方法与并行成像方法相结合的可行性进行了研究。

DESCRIPTION (provided by applicant): Acquisition speed remains a critical issue in cine magnetic resonance imaging (MRI). Structural and functional cardiac imaging, and increasingly also coronary artery and flow imaging, are becoming ever-more important tools in evaluation of a wide range of cardiovascular diseases. All of these scans often involve anatomy that is subject to both cardiac and respiratory motion. Multi-phase ECG-gated imaging is nowadays routinely performed in breath-hold mode, but both the duration and number of breath-hold acquisitions that can be tolerated by the patient are dominant limiting factors for image quality and resolution. These limitations are aggravated by the particular symptoms of many cardiac diseases. Faster MRI data acquisition is being pursued in multiple ways: improved gradient hardware allows faster spatial encoding; phased-array radiofrequency coils offer increased signal-to-noise ratio (SNR); new steady- state free precession acquisition techniques contribute improvements on both these fronts; other innovations, like partial-Fourier imaging, parallel imaging, or reduced field of view (rFOV) methods explore further improvements in imaging speed, often by trading some SNR, by exploiting various types of prior knowledge in the imaging model. Combined use of technologies that improve SNR or speed keeps pushing the limits of clinically feasible applications of cine imaging. However, not all techniques are always compatible, and the gains from all individual techniques are bounded, so the development of additional technologies in this realm is still desired and highly relevant. This proposal will investigate development and evaluation of a novel rFOV technique that promises to offer important advantages over comparable methods in terms of spatial and temporal resolution. The project builds on encouraging preliminary results from a retrospective implementation, using reduced subsets from conventionally acquired MRI data to obtain full-resolution cine reconstructions. Development is proposed of a full prospective implementation of the acquisition method on clinical equipment. Optimization will be investigated with respect to SNR, artifacts, and numerical efficiency. Qualitative and quantitative evaluations will be performed of image quality and flow calculations using the method. Finally, feasibility will be investigated of combining this method and parallel imaging methods.