Novel Radial MRI Methods for Fast, Motion Compensated DCE-MRI

描述(申请人提供)：动态增强磁共振成像(DCE-MRI)在肿瘤的诊断和评估治疗反应中起着关键作用。必须达到高时间分辨率才能准确确定肿瘤增强动力学。此外，需要足够的空间分辨率来识别和跟踪小病变，并评估肿瘤内的异质性。此外，有可能需要大体积或全器官成像来评估多个转移性病变。不幸的是，使用目前的技术，在高时间分辨率、高空间分辨率和体积覆盖之间存在权衡。因此，很难在一次扫描中获得能够同时满足这些不同标准的动态MR成像序列。此外，呼吸运动使在胸部或腹部转移性疾病患者中应用DCE-MRI时的问题更加复杂。因此，以现有的技术，准确评估肺或肝脏肿瘤的血流灌注是极其困难的。在这里，我们建议开发、实施和验证新的策略来改进3DCE-MRI中肿瘤对比动力学的量化，目标是在单个动态序列中实现高时间和空间分辨率，并结合有效的运动补偿。所提出的工作基于基于黄金角度视角顺序方案的径向数据采集和重建策略，该方案允许(1)高度灵活的重建方案以增强时间分辨率；(2)用于呼吸运动补偿的有效的自门控策略。我们的总体假设是，建议的放射状DCE-MRI方法将显著提高呼吸运动严重阻碍准确分析的区域肿瘤血流灌注测量的可靠性。该方案的具体目标如下：具体目标1：探索用于放射状DCE-MRI呼吸运动补偿的新的自门控策略。我们将研究改进的方法来提高呼吸自门控放射状DCE-MRI的时间分辨率，并研究补偿残余运动的技术。具体目标2：制定优化的图像重建策略，以准确评估肿瘤的血流灌注。我们将开发图像重建策略，以优化血流灌注测量的准确性。我们还将研究使图像重建过程更完全自动化的方法。具体目标3：评价建议的径向和常规直线采集方案，以评估良性肝脏病变患者的DCE-MRI。将进行一项随机研究，以检验以下假设：与传统的DCE-MRI图像采集方法相比，AIMS 1和2中提出的方法将产生具有更高图像质量的数据集，并将导致更可重复性的DCE-MRI肿瘤血流定量。公共卫生相关性：动态增强MRI在肿瘤的诊断和评估其对新疗法的反应方面发挥着关键作用。然而，由于高空间分辨率、高时间分辨率和体积覆盖之间的权衡，现有技术很难准确评估病变，特别是位于胸部或腹部的病变，其中呼吸运动使测量进一步复杂化。该方法通过大体积覆盖的高空间和时间分辨率成像，结合有效的呼吸运动补偿策略，提供了一种准确评估肿瘤血流灌注的方法。

DESCRIPTION (provided by applicant): Dynamic contrast-enhanced MRI (DCE-MRI) plays a critical role in the diagnosis of tumors and in assessing their response to therapy. High temporal resolution must be achieved to accurately determine tumor enhancement kinetics. In addition, sufficient spatial resolution is needed for the identification and tracking of small lesions and for assessing intratumoral heterogeneity. Furthermore, there is a potential need for large volume or whole-organ imaging for the evaluation of multiple metastatic lesions. Unfortunately, using current techniques, there are tradeoffs between high temporal resolution, high spatial resolution, and volumetric coverage. It is therefore difficult to acquire a dynamic MR imaging series able to simultaneously meet these diverging criteria in a single scan. Moreover, respiratory motion further complicates the problems when applying DCE-MRI in patients with metastatic disease in the chest or the abdomen. With existing technology, it is therefore extremely difficult to accurately assess perfusion of lung or liver tumors. Here we propose to develop, implement, and validate novel strategies for improved quantification of tumor contrast kinetics in 3D DCE-MRI, with the goal of achieving in a single dynamic series, high temporal and spatial resolutions, in conjunction with effective motion compensation. The proposed work is based on radial data acquisition and reconstruction strategies based on the golden-angle view order scheme, which permit (1) highly flexible reconstruction schemes allowing for enhanced temporal resolution; and (2) effective self-gating strategies for respiratory motion compensation. Our overall hypothesis is that the proposed radial DCE-MRI methodology will significantly improve the reliability of tumor perfusion measurements in regions where respiratory motion can seriously hamper accurate analysis. The specific aims of this proposal are as follows: Specific Aim 1: Explore novel self-gating strategies for compensation of respiratory motion in radial DCE- MRI. We will investigate improved methods to enhance the temporal resolution of respiratory self-gated radial DCE-MRI and investigate techniques to compensate for residual motion. Specific Aim 2: Develop optimized image reconstruction strategies for accurate tumor perfusion assessment. We will develop strategies for image reconstruction that optimizes perfusion measurement accuracy. We will also examine methods to more fully automate the image reconstruction process. Specific Aim 3: Evaluate the proposed radial versus conventional rectilinear acquisition schemes for DCE-MRI evaluation in subjects with benign liver lesions. A randomized study will be carried out to test the hypothesis that the proposed methodologies outlined in Aims 1 and 2-when compared against conventional imaging methods for DCE-MRI image acquisition-will yield data sets with superior image quality, and will result in more reproducible DCE-MRI quantification of tumor perfusion. PUBLIC HEALTH RELEVANCE: Dynamic contrast-enhanced MRI plays a critical role in the diagnosis of tumors and in assessing their response to new therapies. However, due to the tradeoffs among high spatial resolution, high temporal resolution, and volumetric coverage, it is difficult with existing techniques to assess lesions accurately, particularly those that are located in the chest or abdomen where respiratory motion further complicates measurement. The proposed approach provides a means for accurate assessment of tumor perfusion by permitting high spatial and temporal resolution imaging with large volume coverage, in conjunction with an effective strategy for respiratory motion compensation.