Ultra-low-dose photon-counting computed tomography (ULD PCCT) may offer comparable image quality to low-dose PCCT (LD PCCT) with an 87 percent reduction in radiation dosing, according to new prospective research.
For the study, recently published in Radiology, researchers compared ULD PCCT and LD PCCT protocols, performed the same day, in the assessment of 152 patients (median age of 68) with emphysema. The mean effective radiation dose for ULD PCCT was 0.20 mSv in comparison to 1.58 mSv for LD PCCT, according to the study.
The study authors found no significant differences between the two protocols in the assessment of centrilobular emphysema (CLE) and paraseptal emphysema (PSE).
For example, the ULD PCCT protocol detected mild CLE in 19.7 percent of patients in comparison to 18.6 percent of patients with the LD PCCT protocol, and moderate CLE in 33.3 percent of patients in contrast to 33.9 percent with LD PCCT. The ULD PCCT protocol detected substantial PSE in 11.4 percent of patients in comparison to 12.3 percent with the LD PCCT protocol, according to the researchers.
The study authors also noted no differences between the two dosing protocols with respect to automated low attenuation volume (LAV) analysis in bilateral lung, left lung, right lung and individual lobe assessments.
“The ULD protocol provided both comparable visual assessment of emphysema subtypes and severity and equivalent low-attenuation volume measurements … at an 87% lower radiation dose … compared with the LD protocol,” noted lead study author Qianqian Yuan, M.D., who is affiliated with the Department of Radiology at the First Affiliated Hospital of Zhengzhou University in Zhengzhou, China, and colleagues.
Three Key Takeaways
• Major dose reduction without diagnostic compromise. Ultra-low-dose PCCT achieved an 87 percent reduction in radiation dose (0.20 mSv vs. 1.58 mSv) while maintaining comparable image quality to low-dose PCCT for emphysema evaluation.
• Equivalent emphysema characterization. ULD PCCT showed no significant differences from LD PCCT in visual assessment of centrilobular and paraseptal emphysema, with nearly identical detection rates across severity categories.
• Reliable quantitative assessment for follow-up. Automated low attenuation volume (LAV) measurements were equivalent between protocols across whole lung and lobar analyses, supporting ULD PCCT as a viable option for longitudinal COPD/emphysema monitoring despite slightly higher image noise.
While the ULD PCCT protocol did generate a lower reader score for noise than the LD PCCT protocol, the researchers pointed out that ULD PCCT garnered similar subjective reader assessments to LD PCCT with respect to sharpness, artifacts and overall image quality
“Our results support the use of ULD PCCT, which may serve as a valuable tool for emphysema diagnosis and for evaluation and long-term follow-up in patients with chronic obstructive pulmonary disease,” added Yuan and colleagues.
(Editor’s note: For related content, see “Emerging Advances in Photon-Counting Computed Tomography,” “Emphysema on Chest CT Linked to Threefold Higher Risk for COPD Mortality in Next 25 Years” and “Olympus Launches CT-Based AI Software for Emphysema Screening.”)
Beyond the inherent limitations of a single-center study, the authors acknowledged that over 91 percent of the cohort were men and a 158 mL difference in mean inspiratory volume between the protocols. They also acknowledged a lack of prospective trial external validation for the method utilized in the study to convert LAV measurements to emphysema severity grades.
