Imaging of a mobile object at computed tomography

A number of physiologic movements in the body influence the image at CT scanning. The pulsations of the abdominal aorta result in a motion of the retroperitoneal lymph nodes in the transverse plane. In connection with lymphography, the motion of the lymph nodes was analysed in 10 patients. The maximum motion in the transverse plane was 2.5 mm. In phantom experiments an object with a diameter of 10 mm was scanned during pulsating movements. Based on these experiments it was concluded that the motion of the lymph nodes does not seem to be of any importance for the reproduction of the node size, whereas motion in the CT plane will probably impair the resolution and thus the imaging of the internal structure of the nodes.