Advanced NMR/MRI Methods for Liver Cancer

描述（由申请人提供）： 肝癌的早期诊断是决定相关治疗方法的关键。包括磁共振成像（MRI）技术在内的成像技术继续得到发展，尽管标准成像技术（如T2和T1加权MRI）导致结节、腺瘤和肿瘤的可视化，但由于标准MRI的检测限制，患者通常无法成功治疗。在我们的实验室中，我们通过使用核磁共振（NMR）光谱观察生化标志物的轮廓来诊断肝病。使用基于单量子相干光谱的定制射频脉冲程序，我们对胆碱缺乏（CD）饮食诱导的大鼠肝癌发生进行了为期一年的初步研究，与对照组相比，脂肪酸种类存在显著差异。这样的脉冲序列，其中定制的和选择性的射频脉冲被并入到2D异质结相关（HSQC）框架内，允许明确地确定包含在含不饱和脂肪酸的化合物中的双键的数目。以前，这些化合物的NMR光谱信号被认为是化学等效的，因此不能解析为涉及单个脂肪酸部分的存在。然而，通过使用该脉冲序列，我们发现在CD动物中，在饮食的数周内，脂肪酸谱由含有两个至四个双键的化合物主导，并且随着年龄的增长，由含有一个双键的化合物主导，其浓度约为CS（胆碱充足）对照的四倍。我们在这里提出，选择性地观察在体内光谱中的选定信号的方法，将是一种有价值的方法，用于在非常早期的阶段表征肝脏的状态。对概念、方法和脉冲序列程序的改进导致上述定制的HSQC序列，这将导致专门设计用于检测个体代谢物的新型脉冲序列的开发，并将导致适用于疾病的准确和早期诊断的改进的临床MR方法。这构成了拟议的研究课程的两个具体目标之一的基础。在我们研究的第二部分中，我们建议在小动物磁共振成像光谱仪上实施该方法，并在8个月的时间内在选定的时间点上测试该方法在转基因小鼠肝癌模型上的有效性和准确性。本研究的结果将与正常对照进行比较。在每个时间点结束时，将切除每组小鼠的肝脏，并通过我们的改良HSQC方法测定脂肪酸形态，并与通过在小型MRI光谱仪上部署的定制脉冲序列方法获得的结果进行交叉验证。虽然这里的应用停留在动物模型水平，但长期目标是验证临床上通过MRI/S诊断肝癌的非侵入性方法，以及增强当前分期方法的方法。

DESCRIPTION (provided by applicant): The early diagnosis of liver cancer is critical in determining relevant treatment methods. Imaging techniques, including magnetic resonance imaging (MRI) techniques continue to be developed and while standard imaging techniques such as T2 and T1 weighted MRI lead to visualization of nodules, adenomas and tumors, it is generally too late for the patient to be successfully treated due to the limitation of detection with standard MRI. In our laboratory we have pursued the diagnosis of liver disease by observing the profiles of biochemical markers using nuclear magnetic resonance (NMR) spectra. Using a customized radio-frequency pulse program based on single quantum coherence spectroscopy, our preliminary year long study of hepatocarcinogenesis in the rat, induced by a choline deficient (CD) diet, showed marked differences in fatty acid species when compared to controls. Such a pulse sequence, wherein tailored and selective radio-frequency pulses were incorporated within the 2D heteronuclear correlation (HSQC) framework, allowed for the unequivocal determination of the number of double bonds contained in an unsaturated fatty acid containing compound. Previously, the signal from NMR spectra of these compounds were thought to be chemically equivalent and thus could not be resolved to implicate the presence of an individual fatty acid moiety. However, by using this pulse sequence, we have found that in CD animals, the fatty acid profile within weeks of being on the diet, is dominated by compounds containing two to four double bonds and with age is dominated by compounds containing one double bond at a concentration that is approximately four times greater than the CS (choline sufficient) controls. We propose here that the method of selectively observing chosen signals in an in vivo spectrum, will be a valuable method for characterizing the state of the liver at a very early stage. Improvements to the concepts, methods and pulse sequence programs leading to the tailored HSQC sequence mentioned above will lead to development of novel pulse sequences specifically designed to detect individual metabolites, and will lead to improved clinical MR methods suitable for accurate and early diagnosis of disease. This forms the basis for one of two specific aims of the proposed course of study. In the second part of our study we propose to implement the methods on a small animal magnetic resonance imaging spectrometer and test the validity and accuracy of the methods on a transgenic mouse model of liver cancer at chosen time-points over a period of 8 months. The results from this study will be compared with normal controls. At the end of each time point, the liver from each group of mice will be excised and fatty acid speciation determined by our modified HSQC method and cross-validated with the results obtained by the customized pulse sequence methods deployed on the small MRI spectrometer. While the application here stops at the animal model level, the long-term objective is to validate a non-invasive, method for the diagnosis of liver cancer by MRI/S in the clinic and one that augments current staging methods.