Improved Spatial Localization for Spectroscopic Imaging

描述(由申请人提供)： 活体核磁共振质子光谱学已被证明是有临床价值的评估和定位的前列腺肿瘤。然而，由于磁共振光谱成像(MRSI)固有的低信噪比(SNR)，测量时间可能非常长。因此，为了实用于临床前列腺癌MRSI，这些时间必须减少，不可避免的结果是数据质量受到影响。特别是，空间分辨率通常很低。在MRSI中，与低分辨率数据采集相关的一个重要问题是可能存在显著的振铃，即来自邻近甚至远处的体素的一种信号污染渗入感兴趣体素。不受抑制的脂质或水信号的污染可能特别有问题，在某些情况下，使前列腺谱无法诊断。 与标准傅立叶编码相比，非傅立叶编码的一个重要优点是可以消除振铃伪影，因为它能够任意形成成像点扩展函数或PSF。提出了一种新的混合空间编码方法。这种称为PSF-Choice的方法保持了傅里叶编码的简单性，同时包含了非傅立叶编码的灵活性来整形PSF。使用这种方法，可以在不增加成像时间或分辨率或信噪比损失的情况下，实现没有脂质污染的实用的前列腺光谱成像。 模体研究中的核心技术开发和验证，以及在最初一组癌症患者中进行的前列腺癌MRSI可行性测试，将在该项目的R21阶段完成。在项目的R33阶段，计划进行更大规模的临床验证研究，目的是证明新方法将显著增强磁共振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，并计划将其整合到MR图像引导治疗中非常活跃的计划中。

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.