Comparison of image quality between spectral photon-counting CT and dual-layer CT for the evaluation of lung nodules: a phantom study

Salim A. Si-Mohamed*, Joel Greffier, Jade Miailhes, Sara Boccalini, Pierre Antoine Rodesch, Aurélie Vuillod, Niels van der Werf, Djamel Dabli, Damien Racine, David Rotzinger, Fabio Becce, Yoad Yagil, Philippe Coulon, Alain Vlassenbroek, Loic Boussel, Jean Paul Beregi, Philippe Douek

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

31 Citations (Scopus)

Abstract

Objectives: To evaluate the image quality (IQ) of a spectral photon-counting CT (SPCCT) using filtered back projection (FBP) and hybrid iterative reconstruction (IR) algorithms (iDose4), in comparison with a dual-layer CT (DLCT) system, and to choose the best image quality according to the IR level for SPCCT. Methods: Two phantoms were scanned using a standard lung protocol (120 kVp, 40 mAs) with SPCCT and DLCT systems. Raw data were reconstructed using FBP and 9 iDose4 levels (i1/i2/i3/i4/i5/i6/i7/i9/i11) for SPCCT and 7 for DLCT (i1/i2/i3/i4/i5/i6/i7). Noise power spectrum and task-based transfer function (TTF) were computed. Detectability index (d′) was computed for detection of 4 mm ground-glass nodule (GGN) and solid nodule. Two chest radiologists performed an IQ evaluation (noise/nodule sharpness/nodule conspicuity/overall IQ) in consensus, and chose the best image for SPCCT. Results: Noise magnitude was −47% ± 2% lower on average with SPCCT than with DLCT for iDose4 range from i1 to i6. Average NPS spatial frequencies increased for SPCCT in comparison with DLCT. TTF also increased, except for the air insert with FBP, and i1/i2/i3. Higher detectability was found for SPCCT for both GGN and solid nodules. IQ for both types of nodule was rated consistently higher with SPCCT than with DLCT for the same iDose4 level. For SPCCT and both nodules, the scores for noise and conspicuity improved with increasing iDose4 level. iDose4 level 6 provided the best subjective IQ for both types of nodule. Conclusions: Higher IQ for GGN and solid nodules was demonstrated with SPCCT compared with DLCT with better detectability using iDose4. Key Points: Using spectral photon-counting CT compared with dual-layer CT, noise magnitude was reduced with improvements in spatial resolution and detectability of ground-glass nodules and solid lung nodules.As the iDose4level increased, noise magnitude was reduced and detectability of ground-glass and solid lung nodules was better for both CT systems.For spectral photon-counting CT imaging, two chest radiologists determined iDose4level 6 as the best image quality for detecting ground-glass nodules and solid lung nodules.

Original languageEnglish
Pages (from-to)524-532
Number of pages9
JournalEuropean Radiology
Volume32
Issue number1
Early online date29 Jun 2021
DOIs
Publication statusPublished - Jan 2022

Bibliographical note

Funding Information:
This work was supported by European Union Horizon 2020 grant No 643694.

Publisher Copyright:
© 2021, European Society of Radiology.

Fingerprint

Dive into the research topics of 'Comparison of image quality between spectral photon-counting CT and dual-layer CT for the evaluation of lung nodules: a phantom study'. Together they form a unique fingerprint.

Cite this