Optimization of contrast material administration for electrocardiogram-gated computed tomographic angiography of the chest

Objective: Electrocardiogram-gated computed tomographic angiography is increasingly used in the differential diagnosis of acute chest pain. We studied the optimal timing of contrast material injection using a test bolus and a bolus-tracking technique. Materials and Methods: Thirty patients were prospectively included in the study. Volume and flow of high concentration contrast material were adapted to body weight. The scan delay was determined using either a test bolus or a bolus-tracking technique. Attenuation profiles of the different vascular districts were measured to evaluate the timing techniques. Results: In all the patients except for one, an adequate and homogeneous contrast enhancement of more than 200 Hounsfield units (HU) was achieved (285 +/- 45 HU) in the different vascular districts. The pulmonary transit time in the test bolus group was 7 seconds (range, 4-11 seconds). Differences and variability of pulmonary and aortic enhancement were small in both groups (13 +/- 48 HU vs -9 +/- 21 HU), with differences of less than 70 HU over the craniocaudal range and very small intraindividual differences between pulmonary attenuation and systemic attenuation. Conclusions: Contrast administration regimens for electrocardiograragated computed tomographic angiography of the chest can be optimized using the bolus-tracking method in the ascending aorta, with a short delay after trigger. Body weight adaptation of volume and injection rate of the contrast material results in a reliable simultaneous opacification of the pulmonary and systemic vasculature.