Dual-energy CT pulmonary angiography using dual-flow mixture bolus tracking: potential for contrast medium and radiation exposure reduction

Objectives To assess the feasibility and image quality of a bolus tracking protocol with dual-flow mixture for contrast medium volume and radiation dose reduction in dual-energy CT pulmonary angiography (CTPA). Materials and methods Patients with suspected pulmonary embolism (PE) were prospectively included and randomly divided into the dual low-dose or routine CTPA groups. Virtual monoenergetic imaging results at 40 keV for the dual low-dose CTPA group were compared to 100-kV polyenergetic CT images from the routine CTPA group. Attenuation, noise, contrast-to-noise ratio, and figure of merit were determined in multiple pulmonary arteries. Qualitative image quality and PE detection were independently rated by two radiologists. Results The dual low-dose CTPA group showed a significantly higher attenuation in 40-keV virtual monoenergetic imaging (1027.0 ± 287.6 HU vs 391.8 ± 109.0 HU; p < 0.001) with a comparable median contrast-to-noise ratio (33.6 vs 41.0; p = 0.115) and superior figure of merit (711.4 vs 461.5; p = 0.006) in the pulmonary trunk in relation to that observed in the routine CTPA group. Superior vena cava artifacts were reduced (both p ≤ 0.002), while pulmonary branch visualization was preserved ( p = 0.660 and 0.763). Effective radiation dose was lower in the dual low-dose CTPA group (1.61 mSv vs 3.62 mSv; p < 0.001), while PE diagnostic performance did not differ significantly between the two protocols. Conclusion The dual-flow mixture bolus-tracking protocol showed technical feasibility for dual-energy CTPA, achieving substantial reductions in radiation exposure and contrast medium volume while maintaining diagnostically acceptable image quality. Critical relevance statement The dual-flow mixture bolus-tracking protocol with dual-energy CT maintained feasible image quality for PE assessment, facilitating contrast medium volume and radiation exposure reduction. Trial registration NFEC, NFEC-2025-021, approved on January 10, 2025. Key Points Radiation exposure and substantial contrast medium doses during CTPA increased patient risks. Virtual monoenergetic imaging at 40 keV derived from dual-energy CT enhanced pulmonary vascular visualization. The dual-flow mixture technique with dual-energy CT reduced radiation dose and contrast medium volume.