Optimizing computed tomography pulmonary angiography using right atrium bolus monitoring combined with spontaneous respiration.

OBJECTIVES: CT pulmonary angiography (CTPA) aims to provide pulmonary arterial opacification in the absence of significant pulmonary venous filling. This requires accurate timing of the imaging acquisition to ensure synchronization with the peak pulmonary artery contrast concentration. This study was designed to test the utility of right atrium (RA) monitoring in ensuring optimal timing of CTPA acquisition.
METHODS: Sixty patients referred for CTPA were divided into two groups. Group A (n = 30): CTPA was performed using bolus triggering from the pulmonary trunk, suspended respiration and 70 ml of contrast agent (CA). Group B (n = 30): CTPA image acquisition was triggered using RA monitoring with spontaneous respiration and 40 ml of CA. Image quality was compared.
RESULTS: Subjective image quality, average CT values of pulmonary arteries and density difference between artery and vein pairs were significantly higher whereas CT values of pulmonary veins were significantly lower in group B (all P < 0.05). There was no significant difference between the groups in the proportion of subjects where sixth grade pulmonary arteries were opacified (P > 0.05).
CONCLUSIONS: RA monitoring combined with spontaneous respiration to trigger image acquisition in CTPA produces optimal contrast enhancement in pulmonary arterial structures with minimal venous filling even with reduced doses of CA. KEY POINTS: • Bolus tracking (BT) with pulmonary trunk monitoring is widely used in CTPA. • Pulmonary venous contamination is a disadvantage of BT due to transition delay time. • Right atrium monitoring with spontaneous respiration can optimize CTPA. • It produces optimal contrast enhancement in pulmonary arteries with minimal venous filling. • The contrast dose was significantly reduced.