Steric visualization of diseased organs of laboratory small animals by three-dimensionally reconstructing MRI method

利用实验室小动物胸腹部器官的多层螺旋CT图像，用体积射线追踪软件在计算机上叠加，构建三维图像。阳性造影剂口服到胃和十二指肠腔之前，MR成像。采用SIS 300/183型磁共振成像系统，在质子加权条件下（TR= 2000 ms，TE= 20 ms），在7.05T磁场下，拍摄胸部至腹部的二维横断多层螺旋CT图像。层厚为1 mm，采用多层自旋回波法。通过市售图形软件Adobe Photoshop对每个器官（胃、肝、十二指肠、脾、肾、心脏、出生和脊柱）进行伪着色。然后在UNIX计算机上通过体积射线追踪方法将这些彩色多层叠加来构建三维图像。在大鼠和小鼠中，胸部和腹部器官被可视化为伪彩色三维MR图像。透明的三维图像也被构建，这使我们能够清楚地区分个别器官从其他器官的位置，大小和形状。此外，该三维MRI技术可以识别BALB/c小鼠的结肠癌-26细胞系的肝肿瘤和A/J小鼠的乌拉坦诱导的肺肿瘤的组织病理变化。

Using multislice MT images of thoracic and abdominal organs in laboratory small animals, three-dimensional (3-d) images were constructed by superimposing them on the computer with the volume ray tracing software. Positive contrast agent was orally administrated into stomach and duodenum cavities just before MR.imaging. Two-dimensional transversal multislices of MR images from thoracic to abdominal regions were taken by an SIS300/183 MRI system with a magnetic field of 7.05 T under the proton-weighting condition (TR=2000ms, TE=20ms). The slice thickness was I mm and the multislice spin-echo method was employed. Each organs (stomach, liver, duodenum, spleen, kidney heart, born and spine) was pseudo-colored by the commercially available graphic software Adobe Photoshop. The 3-d images were then constructed by superimposing these colored-multislices on a UNIX computer by the volume ray tracing method . In rats and mice, the thoracic and abdominal organs were visualized as the pseudo-colored 3-d MR images. The transparent 3-d images were also constructed which made us possible to clearly distinguished individual organ from other organs with respect the position, size and shape. Furthermore, the pathological changes of tissues could be recognized by this 3-d MRI technique in BALB/c mice with liver tumors derived from colon-26 cell line and in A/J mice with lung tumors induced by urethan.