Dual-Energy CT Reduces Contrast Dose in CTPA Exams Without Sacrificing Image Quality

New research indicates that contrast dose during computed tomography pulmonary angiography (CTPA) exams can be safely reduced by up to 25% when using dual-energy CT (DECT) systems, without compromising image quality. The findings, published in Current Problems in Diagnostic Imaging, suggest a safer imaging protocol for detecting pulmonary embolism (PE), particularly in patients with renal impairment or thyroid dysfunction.

“Computed tomography pulmonary angiography is considered the gold standard in the diagnostic work-up of suspected PE, due to its rapid and noninvasive nature, as well as its wide availability as an imaging modality,” wrote lead author Louise Øksnebjerg Krasniqi, MSc, of the Department of Radiology at Odense University Hospital in Denmark. The authors noted that iodinated contrast media pose risks for certain patients, which makes reducing the dose both clinically and ethically important.

DECT systems have a distinct advantage over traditional single-energy CT in their ability to enhance the spectral properties of iodine. This enables better visualization of contrast within the pulmonary vasculature and facilitates the use of iodine perfusion maps to evaluate pulmonary function. These technical benefits support the use of lower contrast doses while maintaining, or even improving, diagnostic quality.

To evaluate how much contrast could be reduced without affecting diagnostic confidence, the team analyzed CTPA exams performed between August 2024 and March 2025 in 177 patients suspected of having PE. Of these, 92 underwent DECT scans with 45 mL of contrast, while 85 underwent single-energy scans using the standard 60 mL dose. Researchers compared signal-to-noise and contrast-to-noise ratios across five pulmonary artery segments: the main pulmonary artery, left and right pulmonary arteries, and the right and left posterior basal segmental arteries.

Despite the lower contrast volume, the DECT group showed no reduction in attenuation across any of the evaluated segments. In fact, signal-to-noise and contrast-to-noise ratios were higher in the DECT group, suggesting improved overall image quality. Importantly, this improvement was achieved without increasing radiation dose.

These findings are particularly relevant given the broader adoption of DECT systems in clinical practice. The ability to reduce contrast dose without sacrificing diagnostic performance may be a significant advantage for patients at higher risk of contrast-induced complications.

The authors emphasized that while their results are encouraging, further work is needed to personalize contrast dosing strategies. “Future work should focus on individualized approaches to improve both diagnostic consistency and patient safety,” the team wrote. “Tailored approaches that account for both patient-specific physiological factors and scanner technique may improve image quality, support renal protection and enhance cost-effective imaging. This might also reduce variability related to operator experience and procedural workflows.”

The study adds to a growing body of evidence supporting the clinical and operational benefits of dual-energy CT, reinforcing its potential role in enhancing both safety and diagnostic efficacy in pulmonary imaging.