Design of the MRI probe applicable to discrimination of the fine histological changes in brauns of laboratory animals

适用于辨别实验动物内脏细微组织学变化的MRI探头设计

基本信息

批准号：
05556051
负责人：
KUWABARA Mikinori
金额：
$ 7.81万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

Magnetic resonance imaging (MRI) is a unique method to noninvasively observe the structure inside body. Since this is not a method to observe the fine structures inside each tissue by magnifying its image, it is hard to apply this method to small laboratory animals as mice and rats. There is a method to magnify the image on CRT by computer technique, but this method requires the original image to be sharply taken with a high S/N ratio. The NMR theory teaches us that the higher the magnetic field the stronger are the NMR signals obtained. The superconducting magnet used for usual 200 or 300 MHz NMR spectrometry produces the strong and homogeneous magnetic field. We planned to image the inside of the laboratory animal by employing usual 200 MHz NMR spectrometer (Brucker MSL200) . For this purpose, we designed the MRI imaging probe suitable for this machine. As a preliminary experiment, we made a Dadok type Helmholtz coil (50 mm i.d.) resonating at a radiofrequency of 300 MHz as the imaging probe and apply it to the superconducting magnet (Oxford) with the relatively large size of magnet bore (183 mm) producing a magnetic field of 7T.An SIS 300/183 imaging system was operated on a Toshiba workstation. When the sagittal and coronal sections of brains of young (5 weeks old) and aged (24 months old)Wistar rats were imaged using this system, histological alterations of cerebral cortices and enlargement of the third ventricle and hypertrophy of cranical parietal bones relating to degeneration of brains with aging were clearly displayd by this system. The resolution of MR images was 0.8 mm. On the basis of these results, wa subsequently designed an imaging probe suitable for the Brucker MSL200 with a diameter of 25 mm. This probe is now utilized to accumulate imaging data and tested as an NMR microscopy.

磁共振成像（MRI）是一种独特的非侵入性观察体内结构的方法。由于这不是一种通过放大图像来观察每个组织内部精细结构的方法，因此很难将该方法应用于小鼠和大鼠等小型实验动物。有一种方法可以通过计算机技术来放大CRT上的图像，但这种方法需要以高信噪比清晰地拍摄原始图像。核磁共振理论告诉我们，磁场越高，获得的核磁共振信号越强。通常用于 200 或 300 MHz NMR 光谱测定的超导磁体可产生强而均匀的磁场。我们计划使用常用的 200 MHz NMR 波谱仪 (Brucker MSL200) 对实验动物的内部进行成像。为此，我们设计了适合本机的MRI成像探头。作为初步实验，我们制作了一个在300 MHz射频下谐振的Dadok型亥姆霍兹线圈（内径50 mm）作为成像探头，并将其应用于磁体孔径相对较大（183 mm）的超导磁体（Oxford）。产生7T的磁场。SIS 300/183成像系统在东芝工作站上运行。当使用该系统对年轻（5周龄）和老年（24个月大）Wistar大鼠的大脑矢状和冠状切片进行成像时，发现大脑皮质的组织学改变以及与退化相关的第三脑室扩大和颅顶骨肥大该系统清楚地显示了大脑老化的情况。 MR图像的分辨率为0.8毫米。根据这些结果，随后设计了适用于布鲁克 MSL200 的直径为 25 mm 的成像探头。该探针现在用于积累成像数据并作为核磁共振显微镜进行测试。