Optimizing CT pulmonary angiography with patient-adaptive triggering—a novel approach for a “one-stop-shop” evaluation of pulmonary and aortic vasculature

Abstract Objectives Achieving optimal contrast opacification in CT pulmonary angiography (CTPA) is critical for diagnosing pulmonary embolism but remains challenging due to patient-specific hemodynamics. This study evaluated whether a patient-adaptive trigger delay protocol could improve vascular enhancement compared to traditional fixed-delay methods. Materials and methods This retrospective study included 270 patients divided into three groups ( n = 90 each): Group A (fixed delay, pulmonary trunk trigger), Group B (fixed delay, aorta trigger), and Group C (patient-adaptive delay, FAST Bolus, aorta trigger). Objective image quality was assessed using contrast-to-noise ratio (CNR). Subjective image quality, including diagnostic quality and artifact severity, was independently evaluated by two blinded radiologists. Results The patient-adaptive protocol (Group C) yielded significantly higher CNR in the main ( p = 0.03) and segmental lower lobe pulmonary arteries ( p = 0.002) compared to the conventional method (Group A). Aortic CNR was significantly improved in both aorta-triggered groups (B and C) compared to Group A ( p < 0.05). While overall subjective diagnostic quality ratings showed no statistically significant difference between groups, one of two readers rated the adaptive protocol as significantly superior to both fixed-delay methods ( p < 0.0001). Conclusion A patient-adaptive trigger delay with aortic monitoring significantly improves contrast opacification in the peripheral pulmonary arteries and the thoracic aorta. This approach facilitates a comprehensive “one-stop-shop” assessment, potentially enhancing diagnostic confidence for both small peripheral emboli and concurrent aortic disease. Key Points Question Achieving optimal pulmonary artery contrast in CT pulmonary angiography (CTPA) is challenging due to variable patient-specific hemodynamics, which may potentially compromise diagnostic accuracy for pulmonary embolism. Findings A patient-adaptive trigger delay significantly improves contrast-to-noise ratio in peripheral pulmonary arteries and the thoracic aorta compared to traditional fixed-delay methods. Clinical relevance The adaptive bolus-tracking protocol enhances diagnostic quality by optimizing vessel opacification, allowing simultaneous evaluation of pulmonary and aortic pathologies, as well as potentially increasing diagnostic confidence of more peripheric pulmonary vessels. Graphical Abstract