Development of measuring system of head by MRI

本研究的目的是开发一种头部磁共振成像测量系统，志愿者使用SIGNA Horizon 1.5Tesla超导磁共振扫描仪进行扫描。采用磁头线圈作为表面线圈，提高了图像的分辨率。在三维扫描中，采用了坏草技术，并用快速SE技术和常规SE技术进行了对比研究，图像数据通过磁光盘离线传输到工作站的“优势窗口”。该工作站利用多平面图像进行距离、角度等三维测量，采用折叠草技术进行三维体积扫描，与SE技术相比，扫描时间更短。然而，通过三维扫描，图像上的金属伪影在某些情况下是巨大的。由于采集时间不长，金属伪影也不大，因此快速SE技术也是有用的。至于正畸治疗的参考点，MR图像上几乎可以检测到参考点。然而，由于点-N(Nasion)被定义为两个骨骼的融合点，因此很难检测到。虽然在MR图像上骨组织有一些不足之处，但仍可检出鼻尖、嘴唇、舌头、会厌等软组织部位。这些要点对美容问题一定是有用的，也是重要的。

The aim of this study is to develop a measurement system on the head by magnetic resonance imaging.Volunteers were scanned by SIGNA HORIZON,1.5 tesla superconducted MR scanner. Head coil was used as a surface coil to improve the resolution of the image. As three dimensional scan, spoiled GRASS technique was applied and fast SE technique and conventional SE technique were also used as the contrast study.Image data was transferred off-line by magneto-optical disk to the work station "Advantage windows". By this work station, three dimensional measurement, including the distance and angle, was done using multi planar images.Three dimensional volume scanning with spoiled GRASS technique were available for whole head scanning and it took shorter time compared with SE technique. However, metallic artifact was huge in some cases on the image by three dimensional scanning. It was suggested fast SE technique was also useful because acquisition time was not so long and metallic artifact was no so huge.As for the reference points for the orthodontic treatment, almost points were detected on the MR image. However, because point-N (Nasion) is defined as a fusion point of the two bones, it was difficult to detect. Although there were some disadvantages in the bony tissue on MR image, soft tissue points, such as tip of the nose, lip, tongue, epiglottis, were detected. And these points must be useful and important for the cosmetic problem.