To investigate the effectiveness of a saline chaser in reducing the required dose of contrast material while carrying out dynamic CT scans in cattle, six clinically normal Holstein calves were subjected to CT scans of the head in a study using a crossover design. The calves were studied as three groups: group A received only contrast material (600 mgI/kg); group B received a 30 per cent lower dose of the same contrast material followed by 50 ml of saline solution; and group C received a 40 per cent lower dose of the same contrast material followed by 50 ml of saline solution. In all the animals, a power injector was used for administering the contrast material, with an injection rate of 4 ml/s and a pressure of 4.7 to 5.7 kg/cm2. Attenuation values were obtained from the right and left maxillary arteries and dorsal sagittal sinus. There were no significant differences in the maximum enhancement value (MEV) of the maxillary arteries and dorsal sagittal sinus between groups A and B. The MEVs of the maxillary arteries and dorsal sagittal sinus in groups A and B were significantly greater than the MEV in group C (P<0.05). The use of a saline chaser allowed a 30 per cent reduction in the dose of contrast material without decreasing vascular enhancement.
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