Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Mar 22;11(4):301.
doi: 10.3390/bioengineering11040301.

Comparison of Virtual Non-Contrast and True Non-Contrast CT Images Obtained by Dual-Layer Spectral CT in COPD Patients

Manuel Steinhardt  1 , Alexander W Marka  1 , Sebastian Ziegelmayer  1 , Marcus Makowski  1 , Rickmer Braren  1 , Markus Graf  1 , Joshua Gawlitza  1
Affiliations

Comparison of Virtual Non-Contrast and True Non-Contrast CT Images Obtained by Dual-Layer Spectral CT in COPD Patients

Manuel Steinhardt et al. Bioengineering (Basel). .

Abstract

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death. Recent studies have underlined the importance of non-contrast-enhanced chest CT scans not only for emphysema progression quantification, but for correlation with clinical outcomes as well. As about 40 percent of the 300 million CT scans per year are contrast-enhanced, no proper emphysema quantification is available in a one-stop-shop approach for patients with known or newly diagnosed COPD. Since the introduction of spectral imaging (e.g., dual-energy CT scanners), it has been possible to create virtual non-contrast-enhanced images (VNC) from contrast-enhanced images, making it theoretically possible to offer proper COPD imaging despite contrast enhancing. This study is aimed towards investigating whether these VNC images are comparable to true non-contrast-enhanced images (TNC), thereby reducing the radiation exposure of patients and usage of resources in hospitals. In total, 100 COPD patients with two scans, one with (VNC) and one without contrast media (TNC), within 8 weeks or less obtained by a spectral CT using dual-layer technology, were included in this retrospective study. TNC and VNC were compared according to their voxel-density histograms. While the comparison showed significant differences in the low attenuated volumes (LAVs) of TNC and VNC regarding the emphysema threshold of -950 Houndsfield Units (HU), the 15th and 10th percentiles of the LAVs used as a proxy for pre-emphysema were comparable. Upon further investigation, the threshold-based LAVs (-950 HU) of TNC and VNC were comparable in patients with a water equivalent diameter (DW) below 270 mm. The study concludes that VNC imaging may be a viable option for assessing emphysema progression in COPD patients, particularly those with a normal body mass index (BMI). Further, pre-emphysema was generally comparable between TNC and VNC. This approach could potentially reduce radiation exposure and hospital resources by making additional TNC scans obsolete.

Keywords: COPD; computed tomography imaging; dual-layer spectral CT; emphysema quantification; image comparison analysis; lung imaging; radiation exposure; true non-contrast images; virtual non-contrast images.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Comparison of TNC and VNC images and comparison of respective emphysema segmentations from a patient included in this study. (a) TNC. (b) VNC. (c) TNC + Segmentation. (d) VNC + Segmentation. Emphysema = Lung parenchyma < −950 HU. HU = Houndsfield units. Segmentation was done with ImFusion Labels 0.19.3 (ImFusion GmbH, Munich, Germany).
Figure 2
Figure 2
Emphysema. (a) Bland–Altman plot of total amount of LAV in TNC and VNC. (b) Bland–Altman plot of relative amount of LAV in TNC and VNC.
Figure 3
Figure 3
Scatter plots of LAV differences between TNC and VNC images for the following investigated possible confounders: (a) Sex. (b) Age. (c) Time difference between images. (d) Phase of contrast. (e) Iodine amount. (f) Iodine/weight ratio. Data are shown with median (big stroke) and interquartile range (small strokes) in the graph. ns = no significant difference between medians of both groups (p value > 0.05). PAP = Pulmonary arterial phase. PVP = Portal venous phase.
Figure 3
Figure 3
Scatter plots of LAV differences between TNC and VNC images for the following investigated possible confounders: (a) Sex. (b) Age. (c) Time difference between images. (d) Phase of contrast. (e) Iodine amount. (f) Iodine/weight ratio. Data are shown with median (big stroke) and interquartile range (small strokes) in the graph. ns = no significant difference between medians of both groups (p value > 0.05). PAP = Pulmonary arterial phase. PVP = Portal venous phase.
Figure 4
Figure 4
Scatter plot of LAV differences between TNC and VNC images regarding size-specific dosage estimate of TNC images. Data are shown with median (big stroke) and interquartile range (small strokes) in the graph. ** = significant difference between medians of both groups (p value ≤ 0.01).
Figure 5
Figure 5
LAV Differences between TNC and VNC regarding body mass index. (a) Bland–Altmann plot of normal BMI. (b) Bland–Altmann plot of elevated BMI. BMI = Body mass index (kg/m2). Normal = 18.5–24.9 kg/m2. Elevated = >25 kg/m2.
Figure 6
Figure 6
LAV Differences between TNC and VNC regarding water equivalent diameter. (a) Bland–Altmann plot of high DW. (b) Bland–Altman plot of low DW. DW = Water equivalent diameter. High = >270 mm. Low = <270 mm.
Figure 7
Figure 7
Pre-emphysema. (a) Bland–Altman plot of 15th percentile of LAV in TNC and VNC. (b) Bland–Altman plot of 10th percentile of LAV in TNC and VNC.
See this image and copyright information in PMC

References

    1. Vogelmeier C.F., Criner G.J., Martinez F.J., Anzueto A., Barnes P.J., Bourbeau J., Celli B.R., Chen R., Decramer M., Fabbri L.M., et al. Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Lung Disease 2017 Report. GOLD Executive Summary. Am. J. Respir. Crit. Care Med. 2017;195:557–582. doi: 10.1164/rccm.201701-0218PP. - DOI - PubMed
    1. MacNee W. Is Chronic Obstructive Pulmonary Disease an Accelerated Aging Disease? Ann. Am. Thorac. Soc. 2016;13((Suppl. 5)):S429–S437. doi: 10.1513/AnnalsATS.201602-124AW. - DOI - PubMed
    1. Lynch D.A., Al-Qaisi M.A. Quantitative computed tomography in chronic obstructive pulmonary disease. J. Thorac. Imaging. 2013;28:284–290. doi: 10.1097/RTI.0b013e318298733c. - DOI - PMC - PubMed
    1. Heussel C.P., Herth F.J.F., Kappes J., Hantusch R., Hartlieb S., Weinheimer O., Kauczor H.U., Eberhardt R. Fully automatic quantitative assessment of emphysema in computed tomography: Comparison with pulmonary function testing and normal values. Eur. Radiol. 2009;19:2391–2402. doi: 10.1007/s00330-009-1437-z. - DOI - PubMed
    1. Coxson H.O., Dirksen A., Edwards L.D., Yates J.C., Agusti A., Bakke P., Calverley P.M., Celli B., Crim C., Duvoix A., et al. The presence and progression of emphysema in COPD as determined by CT scanning and biomarker expression: A prospective analysis from the ECLIPSE study. Lancet Respir. Med. 2013;1:129–136. doi: 10.1016/S2213-2600(13)70006-7. - DOI - PubMed