Neutron radiography in vivo imaging of mice and rats

The purpose of this study was to analyze water structure in the living body. Male 4-week-old ddy and BALA/C mice and male 2-month-old F344 rats were used as experimental animals. The animals were fed standard CE-2 diet and tap water freely. To induce pulmonary tumors, BALB/C mice was given 0.2 mmol of N-nitrosomorpholine as drinking water for 20 weeks. Neutron radiography was undertaken using X-ray films and video tapes. An X-ray film image was capable of distinguishing extremities and cartilage of the tail from the surrounding tissue. It also clearly visualized transparencies of the bronchi and lung. At 75 weeks after the beginning of the administration of N-nitrosomorpholine, lung tumors were clearly seen. The heart was clearly distinguished from the surrounding lung transparency. The abdomen was visualized as gas transparency of the stomach and intestine. Findings on video images were almost the same as those on X-ray film images. Both image quality and contrasts on video images were slightly inferior to those on X-ray film images. Video images, however, were superior to X-ray film images in visualizing contraction of pulmonary dilatation due to respiration and cardiac dilatation due to heart rate. Neutron radiography has a great potential in visualizing lesions of bone, cartilage and lungs. It would become a useful tool in the analysis of water structure of the tumor. (N.K.)