RESUMO
OBJECTIVE: The diagnostic value of a multiphase CT strongly depends on the correct timepoints of analysis. Therefore, we investigated whether the peak attenuation time in the aorta and portal vein are predictable using easily detectable clinical parameters. Regression equations were developed that enable an approximate prediction of these scan times. MATERIAL AND METHODS: Contrast dynamic CT was performed in 39 anaesthetised dogs of different breeds. The heart rate at the onset of the examination, the age and the body weight were documented. The contrast agent Imeron 300® was injected into a cephalic vein at 3 ml/s with 600 mg iodine/kg body weight using an automatic injector and a dynamic axial CT was started at the same time. The peak enhancement time in the aorta (pETA) and portal vein (pETP) were measured. RESULTS: The mean pETA was 24.5 ± 8.6 seconds and the mean pETP was 43.6 ± 13.4 seconds. There was a strong correlation (r = 0.92) between pETA and body weight in combination with the heart rate, and a moderate correlation (r = 0.66) between pETP and body weight in combination with the age. The regression equation was: pETA = 12.23 + 0.61 body weight - 0.07 heart rate. The time between pETA and pETP was 8-24 seconds in 34 animals. CONCLUSION: To plan the arterial peak the authors recommend the use of the established regression equations based on the statistical results or alternatively bolus tracking to plan the arterial peak. When it is planned to examine the portal venous peak, an interscan duration of 8-14 seconds is recommended.
