Semi-automated volumetry of pulmonary nodules: Intra-individual comparison of standard dose and chest X-ray equivalent ultralow dose chest CT scans

Thorsten Ottilinger; Katharina Martini; Bettina Baessler; Thomas Sartoretti; Ralf W Bauer; Sebastian Leschka; Elisabeth Sartoretti; Joan E Walter; Thomas Frauenfelder; Simon Wildermuth; Hatem Alkadhi; Michael Messerli

doi:10.1016/j.ejrad.2022.110549

Semi-automated volumetry of pulmonary nodules: Intra-individual comparison of standard dose and chest X-ray equivalent ultralow dose chest CT scans

Eur J Radiol. 2022 Nov:156:110549. doi: 10.1016/j.ejrad.2022.110549. Epub 2022 Oct 3.

Affiliations

¹ Division of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, Switzerland; University Zurich, Zurich, Switzerland.
² University Zurich, Zurich, Switzerland; Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland.
³ Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland; Department of Diagnostic and Interventional Radiology, University Hospital Wuerzburg, Wuerzburg, Germany.
⁴ University Zurich, Zurich, Switzerland; Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland; Department of Nuclear Medicine, University Hospital Zurich, Switzerland.
⁵ RNS, Private Radiology and Radiation Therapy Group, Wiesbaden, Germany.
⁶ Division of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, Switzerland.
⁷ University Zurich, Zurich, Switzerland; Department of Nuclear Medicine, University Hospital Zurich, Switzerland.
⁸ Department of Nuclear Medicine, University Hospital Zurich, Switzerland.
⁹ University Zurich, Zurich, Switzerland; Department of Nuclear Medicine, University Hospital Zurich, Switzerland. Electronic address: michael.messerli@usz.ch.

PMID: 36272226
DOI: 10.1016/j.ejrad.2022.110549

Abstract

Purpose: To assess the performance of semi-automated volumetry of solid pulmonary nodules on single-energy tin-filtered ultralow dose (ULD) chest CT scans at a radiation dose equivalent to chest X-ray relative to standard dose (SD) chest CT scans and assess the impact of kernel and iterative reconstruction selection.

Methods: Ninety-four consecutive patients from a prospective single-center study were included and underwent clinically indicated SD chest CT (1.9 ± 0.8 mSv) and additional ULD chest CT (0.13 ± 0.01 mSv) in the same session. All scans were reconstructed with a soft tissue (Br40) and lung (Bl64) kernel as well as with Filtered Back Projection (FBP) and Iterative Reconstruction (ADMIRE-3 and ADMIRE-5). One hundred and forty-eight solid pulmonary nodules were identified and analysed by semi-automated volumetry on all reconstructions. Nodule volumes were compared amongst all reconstructions thereby focusing on the agreement between SD and ULD scans.

Results: Nodule volumes ranged from 58.5 (28.8-126) mm³ for ADMIRE-5 Br40 ULD reconstructions to 72.5 (39-134) mm³ for FBP Bl64 SD reconstructions with significant differences between reconstructions (p < 0.001). Interscan agreement of volumes between two given reconstructions ranged from ICC = 0.605 to ICC = 0.999. Between SD and ULD scans, agreement of nodule volumes was highest for FBP Br40 (ICC = 0.995), FBP Bl64 (ICC = 0.939) and ADMIRE-5 Bl64 (ICC = 0.994) reconstructions. ADMIRE-3 reconstructions exhibited reduced interscan agreement of nodule volumes (ICCs from 0.788 - 0.882).

Conclusions: The interscan agreement of node volumes between SD and ULD is high depending on the choice of kernel and reconstruction algorithm. However, caution should be exercised when comparing two image series that were not identically reconstructed.

Keywords: Computed tomography; Iterative reconstruction; Kernel; Radiation dose; Ultralow dose.