NOVEL ENCODING TECHNOLOGY FOR MRI

本提案的目标是探索一个全新的MRI空间编码领域。这个名为PERL的字段在x维上是周期性的，在y维上是线性的。它是唯一的，因为它是两个正交空间变量的函数，并且是空间周期的。重构也是独一无二的，它涉及一维的傅里叶变换和另一维的贝塞尔函数积分变换的解。理论分析表明，PERL为MRI提供了几种令人兴奋的可能性。例如，PERL MRI的空间分辨率可以在不增加成像时间或信噪比的情况下提高，因此可能非常适合高分辨率肿瘤成像。此外，PERL重建的基函数是空间定位的，因此PERL可能是只有部分视场发生变化的手术指导的理想候选者。此外，该场的周期性特性使一种优雅的流量测量技术成为可能，即移动相位前，允许相对于移动参考系的速度相关测量。理论还表明，连续的PERL自旋回波彼此的相位为90，这意味着数据采集可能比传统方法增加两倍。此外，PERL分析提供了一种方法，通过提供一种机制，包括这些传统线圈的非线性区域，来增强使用标准“线性”梯度线圈的传统MRI的视场。PERL线圈自然是在扁平线圈形式上实现的，因此可以直接定位在与主体相邻的位置，从而作为高效率的表面“梯度”线圈运行。PERL线圈也是可取的，因为它具有零洛伦兹力，最小的涡流和非常低的电感。在研究计划中，我们将设计和制造PERL线圈，包括一个集成的RF线圈，并实验实现PERL MRI。将执行基本实验和数值模拟来测试PERL的上述独特特性，以了解PERL相对于潜在临床应用的真正优势和劣势。

This proposal's goal is to explore a radically new spatial encoding field for MRI. The field, called PERL, is PERiodic in the x-dimension and Linear in the y-dimension. It is unique because it is a function of two orthogonal spatial variables and is spatially periodic. The reconstruction is also unique, involving a Fourier transform in one dimension and the solution of a Bessel function integral transform in the other. Theoretical analysis shows that PERL offers several exciting possibilities for MRI. For example, the spatial resolution for PERL MRI can be increased with no cost in either imaging time or SNR and thus may be well suited for high-resolution tumor imaging. Further, the basis functions for the PERL reconstruction are spatially localized and thus PERL may be an ideal candidate for surgical guidance where only a portion of the field of view is changing. In addition, the periodic nature of the field enables an elegant flow measurement technique, i.e. a moving phase front, allowing velocity dependent measurements relative to a moving reference frame. Theory also shows that successive PERL spin echoes are 90 out of phase with each other, implying that data acquisition may be increased by a factor of two over traditional methods. Furthermore, the PERL analysis provides a way to enhance the FOV in traditional MRI that uses standard "linear" gradient coils by providing a mechanism to include nonlinear regions of these traditional coils. A PERL coil is naturally implemented on a flat coil form and can thus be positioned immediately adjacent to the body, thereby operating as a high efficiency surface "gradient" coil. The PERL coil is also desirable in that it has zero Lorentz force, minimal eddy currents and very low inductance. In the research proposed, we will design and build PERL coils, including an integrated RF coil, and experimentally implement PERL MRI. Basic experiments and numerical simulations will be performed to test the above-mentioned unique features of PERL to obtain an understanding of where its real strengths and weaknesses lie relative to potential clinical applications.