Intra-patient variability of iodine quantification across different dual-energy CT platforms: assessment of normalization techniques

Simon Lennartz; Jinjin Cao; Nisanard Pisuchpen; Shravya Srinivas-Rao; Joseph J Locascio; Anushri Parakh; Peter F Hahn; Achille Mileto; Dushyant Sahani; Avinash Kambadakone

doi:10.1007/s00330-023-10560-z

Intra-patient variability of iodine quantification across different dual-energy CT platforms: assessment of normalization techniques

Eur Radiol. 2024 Jan 8. doi: 10.1007/s00330-023-10560-z. Online ahead of print.

Authors

Affiliations

¹ Department of Radiology, Abdominal Radiology Division, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, White 270, Boston, MA, 02114-2696, USA.
² Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937, Cologne, Germany.
³ Department of Radiology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand.
⁴ Harvard Catalyst Biostatistical Unit, Harvard Medical School/Massachusetts General Hospital, Boston, MA, USA.
⁵ Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA.
⁶ Department of Radiology, University of Washington, UWMC Radiology RR218, 1959 NE Pacific St, Seattle, WA, 98195, USA.
⁷ Department of Radiology, Abdominal Radiology Division, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, White 270, Boston, MA, 02114-2696, USA. akambadakone@mgh.harvard.edu.

PMID: 38189979
DOI: 10.1007/s00330-023-10560-z

Abstract

Objectives: To investigate intra-patient variability of iodine concentration (IC) between three different dual-energy CT (DECT) platforms and to test different normalization approaches.

Methods: Forty-four patients who underwent portal venous phase abdominal DECT on a dual-source (dsDECT), a rapid kVp switching (rsDECT), and a dual-layer detector platform (dlDECT) during cancer follow-up were retrospectively included. IC in the liver, pancreas, and kidneys and different normalized ICs (NIC_PV:portal vein; NIC_AA:abdominal aorta; NIC_ALL:overall iodine load) were compared between the three DECT scanners for each patient. A longitudinal mixed effects analysis was conducted to elucidate the effect of the scanner type, scan order, inter-scan time, and contrast media amount on normalized iodine concentration.

Results: Variability of IC was highest in the liver (dsDECT vs. dlDECT 28.96 (14.28-46.87) %, dsDECT vs. rsDECT 29.08 (16.59-62.55) %, rsDECT vs. dlDECT 22.85 (7.52-33.49) %), and lowest in the kidneys (dsDECT vs. dlDECT 15.76 (7.03-26.1) %, dsDECT vs. rsDECT 15.67 (8.86-25.56) %, rsDECT vs. dlDECT 10.92 (4.92-22.79) %). NIC_ALL yielded the best reduction of IC variability throughout all tissues and inter-scanner comparisons, yet did not reduce the variability between dsDECT vs. dlDECT and rsDECT, respectively, in the liver. The scanner type remained a significant determinant for NIC_ALL in the pancreas and the liver (F-values, 12.26 and 23.78; both, p < 0.0001).

Conclusions: We found tissue-specific intra-patient variability of IC across different DECT scanner types. Normalization mitigated variability by reducing physiological fluctuations in iodine distribution. After normalization, the scanner type still had a significant effect on iodine variability in the pancreas and liver.

Clinical relevance statement: Differences in iodine quantification between dual-energy CT scanners can partly be mitigated by normalization, yet remain relevant for specific tissues and inter-scanner comparisons, which should be taken into account at clinical routine imaging.

Key points: • Iodine concentration showed the least variability between scanner types in the kidneys (range 10.92-15.76%) and highest variability in the liver (range 22.85-29.08%). • Normalizing tissue-specific iodine concentrations against the overall iodine load yielded the greatest reduction of variability between scanner types for 2/3 inter-scanner comparisons in the liver and for all (3/3) inter-scanner comparisons in the kidneys and pancreas, respectively. • However, even after normalization, the dual-energy CT scanner type was found to be the factor significantly influencing variability of iodine concentration in the liver and pancreas.

Keywords: Contrast media; Reproducibility of results; Tomography (X-ray computed).

Abstract

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