Improvement of Contrast Media Enhancement in CTA Evaluating Pulmonary Embolism by Utilizing ‘Delayed’ Bolus Tracking in the Descending Aorta

BACKGROUND: As standard bolus triggering in the pulmonary trunk sometimes fails to achieve sufficient enhancement in the pulmonary arteries, the study investigates an alternative, ‘delayed’ position of the tracking ROI in the descending aorta. MATERIAL/METHODS: Retrospective analysis of 143 patients suspected of pulmonary embolism investigated with 3 different scanners (16 to 80 rows) in clinical routine. Bolus triggering with 120 hounsfield units (HU) was performed using the pulmonary trunk (n=70) or descending aorta (n=73) after application of 70 to 120 mL of contrast agent, Iomeprol 300. Student’s t-test was applied to compare vascular enhancement. Additional factors were analysed by a regression analysis. RESULTS: Positioning of the tracking ROI in the descending aorta achieved a significantly higher contrast enhancement in the pulmonary trunk with a mean increase of 63 HU (p<0.001). CONCLUSIONS: In CTA, delayed acquisition by using the descending aorta for bolus triggering can improve the enhancement of the pulmonary trunk to investigate a pulmonary embolism. Furthermore, the scan protocol simultaneously allows to rule out aortic pathologies as an alternative cause for a similar clinical condition.