Clinical application of ultra high field magnetic resonance imaging and spectroscopy

从基本的和技术的角度来看，使用高场系统获得VRI和MRS的可能性和问题进行了研究。第一个主题是使用动物用实验机（4.7 T和7.0 T）设计最合适的局部光谱方法。结果表明，化学位移成像（CSI）方法对^1H-和^1 P-MRS的检测效果最好<31>，并据此决定发展第二种方法。通过如下解决各种问题来实现1H-CSI。脉冲序列被设计为从具有良好定位和良好水抑制的小体素获得良好的光谱。通过调节去相位和再相位梯度来补偿涡流伪影。数据处理软件设计为自动校正基线和相位失真，并通过使用曲线拟合数据进行代谢物图谱绘制。因此，获得了256个体素的光谱，每个体素的尺寸为2.5 × 2.5 × 2.5 mm。 ...更多信息 d在实验系统中50分钟内。在实验诱导的脑缺血频谱中，N-乙酰天冬氨酸（NAA）峰降低，乳酸峰增加。代谢物图谱清晰地显示了代谢物在脑内分布的变化。由于临床超高场系统的梯度、系统和射频放大器仍存在问题，因此通过将CSI方法应用于现有的临床系统（1.5 T）进行了检查。结果表明，在25分钟内，可以从正常和患者脑中的256个体素获得光谱，其面积为1 × 1 × 2cm。总之，CSI方法是临床应用的必要方法，有必要继续研究和发展这种方法在高场和超高场系统中的临床应用。作为实验性脑水肿模型，采用4.7T实验性MR机对细胞毒性脑水肿和血管源性脑水肿模型进行检查。使用的脉冲序列是具有附加运动探测梯度（MPG）脉冲的自旋回波方法。在平行于MPGS方向的白色物质中检测到更快的扩散。垂直于MPGS检测到较慢的扩散。这表明有髓轴突纤维的扩散各向异性被定义在白色物质中。弥散加权成像有助于分析各种脑部疾病。通过使用超高场MRI/S系统，应该可以获得光谱扩散加权图像，该图像将澄清各种代谢物在组织中的扩散。少

The possibility and problems of-obtaining VRI and MRS using a high field system were examined from the basic and technical point of view. The first subject was to design the most appropriate method for localized spectra by using an experimental machine for Animal use (4.7 T and 7.0 T). As the result, the chemical shift imaging (CSI) method is best both for ^1H- and ^<31>P-MRS. According to this result, the second was decided to develop. the ^1H-CSI by resolving various problems as follows. The pulse sequence was designed to get good spectra from small voxels with good localization and with good water suppression The eddy current artifact was compensated by adjusting the dephasing and rephasing gradients. The software for data processing were designed to be that the baseline and phase distortions were corrected automatically and the metabolite mapping was carried out by using the curve-fitted data for each peak. Thus, spectra of 256 voxels with a size of 2.5x2.5x2.5 mm each were obtaine … More d within 50 minutes in the experimental system. In the spectrum of experimentally induced brain ischemia, a N-acetyl aspartate (NAA) peak decreased and a lactate peak increased. The metabolite mapping clearly visualized the changes of the distribution of metabolites in the brain. Since there is still problems in the gradient, system and RF amplifier of the clinical ultra-highs field system, the CSI method was examined by applying to the clinical system now available (1.5 T). As the result, spectra could be obtained from 256 voxels with a sue of lxlx2 cm in the normal and patient brains within 25 minutes. In conclusion, the CSI method is essential for clinical use and it is necessary to continue the research of applying and developing this method for clinical use both in the high-field and ultra-high field systems.The second suiects is to develop a diffusion weighted imaging method on a high field experimental MRI/S sytem. As an experimental brain edema models, cytotoxic and vasogenic brain edema models were examined using a 4.7 T experimental MR machine. The pulse sequence used was a spin echo method with additional motion-probing gradient (MPG) Pulses. Faster diffusion was detected in the white matter parallel to the direction of MPGS. Slower diffusion was detected perpendicular to MPGS. This indicated that the diffusion anisotropy of myelinated axonal fibers was defined in white matter. A Diffusion weighted image is useful to analyse the various brain disorders. By using the ultra-high field MRI/S system, it is supposed to be possible to obtain the spectroscopic diffusion weighted image which will clarifythe diffusion of various metabolites in the tissue. Less