Quantitative chest computed tomography: regional differences in dual-energy-derived virtual vs. true non-contrast...

Area of Science:

• Radiology
• Medical Imaging
• Pulmonary Medicine

Background:

• Quantitative analysis of chest computed tomography (CT) typically necessitates non-contrast scans.
• Multi-energy CT-derived virtual non-contrast (VNC) images present a potential alternative to true non-contrast (TNC) scans, aiming to reduce radiation exposure and scan time.

Purpose of the Study:

• To quantitatively compare VNC and TNC images derived from dual-energy CT.
• To evaluate regional differences in pulmonary tissue analysis between VNC and TNC images.

Main Methods:

• A bi-center retrospective study included 48 patients who underwent both contrast-enhanced dual-energy and non-contrast chest CT scans.
• Scans were co-registered and segmented into various lung regions (whole lung, center/periphery, ventral/dorsal, upper/middle/lower thirds).
• Quantitative parameters including mean lung density, attenuation volumes, and the lower 15th percentile were computed and compared using correlation and agreement analyses.

Main Results:

• High correlation and agreement (Pearson's and intraclass correlation coefficients > 0.9) were observed for mean lung density, low attenuation volume, and the lower 15th percentile across the whole lung.
• Agreement for high attenuation volume was slightly less pronounced (ICC, 0.84).
• Slight regional differences in mean lung density were noted, with variations observed between the upper, middle, and lower lung thirds.

Conclusions:

• Quantitative analysis of pulmonary tissue can be reliably performed using VNC images.
• Despite minor regional variations, VNC images demonstrate high agreement with TNC images for key quantitative metrics.
• VNC imaging holds promise for streamlining chest CT protocols by potentially eliminating the need for separate TNC scans.