Abstract
Objectives
To compare the spectral performance of dual-energy CT (DECT) platforms using task-based image quality assessment based on phantom data.
Materials and methods
Two CT phantoms were scanned on four DECT platforms: fast kV-switching CT (KVSCT), split filter CT (SFCT), dual-source CT (DSCT), and dual-layer CT (DLCT). Acquisitions on each phantom were performed using classical parameters of abdomen-pelvic examination and a CTDIvol at 10 mGy. Noise power spectrum (NPS) and task-based transfer function (TTF) were evaluated from 40 to 140 keV of virtual monoenergetic images. A detectability index (d′) was computed to model the detection task of two contrast-enhanced lesions as function of keV.
Results
The noise magnitude decreased from 40 to 70 keV for all DECT platforms, and the highest noise magnitude values were found for KVSCT and SFCT and the lowest for DSCT and DLCT. The average NPS spatial frequency shifted towards lower frequencies as the energy level increased for all DECT platforms, smoothing the image texture. TTF values decreased with the increase of keV deteriorating the spatial resolution. For both simulated lesions, higher detectability (d′ value) was obtained at 40 keV for DLCT, DSCT, and SFCT but at 70 keV for KVSCT. The detectability of both simulated lesions was highest for DLCT and DSCT.
Conclusion
Highest detectability was found for DLCT for the lowest energy levels. The task-based image quality assessment used for the first time for DECT acquisitions showed the benefit of using low keV for the detection of contrast-enhanced lesions.
Key Points
• Detectability of both simulated contrast-enhanced lesions was higher for dual-layer CT for the lowest energy levels.
• The image noise increased and the image texture changed for the lowest energy levels.
• The detectability of both simulated contrast-enhanced lesions was highest at 40 keV for all dual-energy CT platforms except for fast kV-switching platform.
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Abbreviations
- CT:
-
Computed tomography
- CTDIvol :
-
Volume CT dose index
- d′:
-
Detectability index
- DECT:
-
Dual-energy CT
- DLCT:
-
Dual-layer CT
- DSCT:
-
Dual-source CT
- HU:
-
Hounsfield unit
- KVSCT:
-
Fast kV-switching CT
- N CT :
-
CT number
- NPS:
-
Noise power spectrum
- SFCT:
-
Split filter CT
- TTF:
-
Task-based transfer function
- VMI:
-
Virtual monoenergetic image
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Acknowledgments
We are deeply grateful to J. Solomon for support for the use of imQuest software. We also thank F. Mahinc and G. Raymond for their support in the study. We thank S. Kabani for her help in editing the manuscript.
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The scientific guarantor of this publication is Jean Paul Beregi.
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Greffier, J., Si-Mohamed, S., Dabli, D. et al. Performance of four dual-energy CT platforms for abdominal imaging: a task-based image quality assessment based on phantom data. Eur Radiol 31, 5324–5334 (2021). https://doi.org/10.1007/s00330-020-07671-2
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DOI: https://doi.org/10.1007/s00330-020-07671-2