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

Abstract

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. 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. 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). 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. 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.