Improved Spatial Localization for Spectroscopic Imaging

描述（由申请人提供）： 体内磁共振质子波谱已被证明是临床上有价值的评估和定位肿瘤的前列腺。然而，由于MR光谱成像（MRSI）中固有的低信噪比（SNR），测量时间可能非常长。因此，为了实际用于临床前列腺MRSI，必须减少这些时间，不可避免的结果是数据质量受到影响。特别地，空间分辨率通常非常低。与低分辨率数据采集相关的MRSI中的一个重要问题是可能存在显著的振铃，即，一种从邻近甚至远距离体素向感兴趣体素中的信号污染的渗出。 来自未抑制的脂质或水信号的污染可能特别成问题，在某些情况下，使前列腺光谱对诊断无用。 非傅立叶编码优于标准傅立叶编码的重要优点在于，由于能够任意地成形成像点扩展函数或PSF，因此可以消除振铃伪影。提出了一种新的混合空域编码方法。该方法称为PSF选择，保持了傅立叶编码的简单性，同时包括非傅立叶编码的灵活性来塑造PSF。利用这种方法，可以实现没有脂质污染的前列腺的实际光谱成像，而没有成像时间的额外成本或分辨率或SNR的损失。 体模研究中的核心技术开发和确认，沿着在初始癌症患者组中进行前列腺MRSI的可行性测试，将在本项目的R21阶段完成。在该项目的R33阶段，计划进行一项更大规模的临床验证研究，旨在证明新方法将显着增强MR波谱作为前列腺癌诊断工具的能力。此外，R33阶段将进一步增强该方法沿着计划将其整合到MR图像引导治疗中非常活跃的项目中。

DESCRIPTION (provided by applicant): In-vivo MR proton spectroscopy has been shown to be clinically valuable for assessing and localizing tumors in the prostate. However, due to the inherently low signal-to-noise ratio (SNR) in MR spectroscopic imaging (MRSI), measurement times can be very long. Thus, to be practical for clinical prostate MRSI, these times must be reduced, with the inevitable result that data quality suffers. In particular, spatial resolution is generally very low. A significant problem in MRSI, related to low-resolution data acquisition, is that there can be significant ringing, i.e., a kind of bleeding of signal contamination into the voxel-of-interest, from neighboring and even distant voxels. Contamination from unsuppressed lipid or water signal can be especially problematic, in some cases, rendering prostate spectra useless for diagnosis. An important advantage of non-Fourier encoding over standard Fourier encoding, is that ringing artifact can be eliminated because of the ability to arbitrarily shape the imaging point-spread-function, or PSF. A new hybrid spatial encoding method is proposed. The method, called PSF-Choice, maintains the simplicity of Fourier encoding while including the flexibility of non-Fourier encoding to shape the PSF. With this method, practical spectroscopic imaging of the prostate that is free from lipid contamination can be achieved with no additional cost in imaging time or loss in resolution or SNR. Core technical development and validation in phantom studies, along with a feasibility testing for prostate MRSI in an initial group of cancer patients will be completed in the R21 phase of this project. In the R33 phase of the project, a much larger clinical validation study is planned with the aim to demonstrate that the new method will significantly enhance the power of MR spectroscopy as a diagnostic tool for prostate cancer diagnosis. In addition, the R33 phase will feature further enhancements to the method along with a plan for integration into a very active program in MR image-guided therapy.