B1 Based Localization for MRSI of Human Brain at 7T

基于 B1 的 7T 人脑 MRSI 定位

• 批准号: 8064693
• 负责人: Hoby P Hetherington
• 金额: $ 45.91万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8064693
• 关键词: Acute; Adult; Amino Acids; Ammonia; Brain; Brain Neoplasms; Brain region; Cells; Cerebral Neoplasm; Choline; Clinical; Coupled; Creatine; Data; Dependence; Deposition; Detection; Development; Disadvantaged; Discipline; Disease; Effectiveness; Elements; Epilepsy; Evaluation; Generations; Glutamates; Glutamine; Goals; Guidelines; Head; Health; Heating; Human; Hyperammonemia; Image; Individual; Inflammation; Inflammatory; Lipids; Liver Failure; Location; Magnetic Resonance Spectroscopy; Malignant Glioma; Measurement; Methods; Monitor; Necrosis; Parietal; Patients; Performance; Phase; Physiologic pulse; Play; Proliferating; RF coil; Radiation therapy; Reporting; Reproducibility; Research; Resolution; Role; Shapes; Signal Transduction; Slice; Spatial Distribution; Surface; System; Technology; Testing; Therapeutic; Time; Tissues; Vendor; base; chemotherapy; design; first episode schizophrenia; flexibility; frontal lobe; frontal sinus; imaging modality; improved; interest; model development; neoplastic cell; novel; response; spectroscopic imaging; transmission process; treatment duration; tumor; tumor progression; uptake

DESCRIPTION (provided by applicant): With recent advances in magnet technology, ultrahigh field magnets (7T and higher) with bore sizes capable of accommodating the adult human head have become available from a variety of research and clinical vendors. The increased field strength confers the intrinsic advantages of increased SNR and for spectroscopic studies, increased spectral resolution and spectral simplification of J coupled resonances such as glutamate and glutamine. Thus, spectroscopic imaging at 7T should provide an ideal platform for evaluating these compounds. Unfortunately, despite the presence of 7T systems dating from late 1990s, there have been few reports of their use in spectroscopic imaging studies. This limitation is largely due to the intrinsic inefficiencies of generating sufficient B1 strength at high field and the resulting increases more than a factor of 10 in power deposition. Thus, many conventional spectroscopic imaging sequences result in long echo times and can exceed FDA guidelines for tissue heating when applied at 7T. To overcome these limitations we will develop novel methods for spectroscopic imaging at 7T which combine both pulse sequence design, B1 shimming and the development of multi-geometry transceiver arrays. Although contrast enhanced and FLAIR imaging are routinely used for monitoring the response to radiochemotherapy in patients with malignant gliomas, false positives (pseudoprogression) arising from necrosis and inflammation in the absence of tumor progression during the acute and sub-acute periods (first 60 days of treatment) occur in 20-40% of the patients being treated. This severely limits the interpretation of early imaging studies, delaying optimal therapeutic response and decreasing survival times. In addition to the common findings of increased choline, lactate and mobile lipids (which are also found in inflammatory cells), cerebral tumors appear to show elevated concentrations glutamine. This is consistent with the major role which glutamine plays in biosynthetic and anapleurotic activities in proliferating tumor cells. Thus, short TE MRSI measurements of glutamine have the potential to significantly aid the serial evaluation of tumors in response to therapy. Therefore, to evaluate the utility of the methods, we will determine if MRSI measurements of glutamine can resolve progression from pseudoprogression in patients with malignant gliomas being treated with radiochemotherapy. PUBLIC HEALTH RELEVANCE: Although spectroscopic imaging at 7T should provide an ideal platform for measurements of amino acids such as glutamate and glutamine, decreased transmission efficiency, large signal intensity losses and power deposition make use of conventional methods difficult. To overcome these limitations we will develop novel methods for spectroscopic imaging at 7T, which combine both pulse sequence design and new ways of shaping RF fields spatially with multi-element coil arrays, which dramatically decrease power deposition and maintain optimal signal detection. We will use these methods to determine if spectroscopic imaging of glutamine can aid in the monitoring the response of malignant gliomas to radiochemotherapy.

描述（由申请人提供）：随着磁体技术的最新进展，孔径尺寸能够容纳成人头部的超高场磁体（7T 及更高）已可从各种研究和临床供应商处获得。场强的增加赋予了增加信噪比和光谱研究、增加光谱分辨率和 J 耦合共振（例如谷氨酸和谷氨酰胺）的光谱简化的内在优势。因此，7T 的光谱成像应该为评估这些化合物提供理想的平台。不幸的是，尽管 7T 系统早在 20 世纪 90 年代末就已经存在，但很少有关于它们在光谱成像研究中使用的报道。这种限制主要是由于在高场下产生足够的 B1 强度的固有低效率，导致功率沉积增加超过 10 倍。因此，许多传统的光谱成像序列会导致回波时间较长，并且在 7T 下应用时可能会超出 FDA 组织加热指南。为了克服这些限制，我们将开发 7T 光谱成像的新方法，该方法结合了脉冲序列设计、B1 匀场和多几何收发器阵列的开发。尽管对比增强和 FLAIR 成像通常用于监测恶性胶质瘤患者对放化疗的反应，但在急性和亚急性期（治疗的前 60 天）期间，在没有肿瘤进展的情况下，坏死和炎症引起的假阳性（假性进展）出现在 20-40% 的接受治疗的患者中。这严重限制了早期影像学研究的解释，延迟了最佳治疗反应并缩短了生存时间。除了胆碱、乳酸和流动脂质（也存在于炎症细胞中）增加的常见发现之外，脑肿瘤似乎还表现出谷氨酰胺浓度升高。这与谷氨酰胺在增殖肿瘤细胞的生物合成和回补活性中所起的主要作用是一致的。因此，谷氨酰胺的短期 TE MRSI 测量有可能显着帮助对肿瘤对治疗的反应进行连续评估。因此，为了评估这些方法的实用性，我们将确定谷氨酰胺的 MRSI 测量是否可以解决接受放化疗的恶性神经胶质瘤患者的假性进展。公共健康相关性：虽然 7T 光谱成像应该为谷氨酸和谷氨酰胺等氨基酸的测量提供理想的平台，但传输效率降低、信号强度损失大和功率沉积使得传统方法的使用变得困难。为了克服这些限制，我们将开发 7T 光谱成像的新方法，该方法将脉冲序列设计和利用多元件线圈阵列在空间上塑造射频场的新方法相结合，从而大大减少功率沉积并保持最佳信号检测。我们将使用这些方法来确定谷氨酰胺的光谱成像是否可以帮助监测恶性胶质瘤对放化疗的反应。