Simon Lennartz1,2, Anushri Parakh1, Jinjin Cao1, Avinash Kambadakone3. 1. Department of Radiology, 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, University Cologne and University Hospital Cologne, Kerpener Straße 62, 50937, Cologne, Germany. 3. Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, White 270, Boston, MA, 02114-2696, USA. akambadakone@mgh.harvard.edu.
Abstract
OBJECTIVES: The accuracy of virtual unenhanced (VUE) images has been extensively investigated, yet data on their longitudinal reproducibility is limited. The study purpose was to evaluate the longitudinal reproducibility of VUE attenuation measurements on three different dual-energy CT (DECT) scanner types. METHODS: A total of 137 patients with repeated abdominal DECT either on a rapid kV switching (rsDECT; n = 46), a dual-layer detector (dlDECT; n = 43), or a dual-source scanner (dsDECT; n = 48) were retrospectively included. Attenuation was measured on VUE and corresponding contrast-enhanced images in the liver, spleen, kidneys, aorta, portal vein, and fat. Longitudinal reproducibility was evaluated by calculating the absolute inter-scan differences (HU) and the inter-scan variation (%). Measurement pairs with differences ≤ 10 HU were considered reproducible. Influence of contrast-enhanced attenuation on VUE reproducibility was analyzed using linear regression. RESULTS: The scanner-specific cohorts showed similar age (p-range: 0.35-0.99), sex (p-range: 0.68-1), body weight (p-range: 0.26-0.87), body diameter (p-range: 0.34-0.76), and inter-scan time (p-range: 0.52-0.83). In total, 94.9% of VUE measurements were reproducible for rsDECT, 93.8% for dlDECT, and 90.6% for dsDECT. Overall inter-scan variation was lowest in fat (4.0 (1.7-8.2)%) and highest in tissues with high contrast enhancement: the aorta (13.3 (4.6-21.3)%), portal vein (10.8 (5.7-19.8)%), and kidneys (10.7 (3.9-18.0)%). Significant differences in inter-scan variation were found between the scanner types for the aorta, portal vein, kidneys, and spleen. Inter-scan differences in contrast-enhanced attenuation significantly influenced inter-scan differences in VUE attenuation (p < 0.001; t-ratio: 4.34). CONCLUSIONS: Longitudinal reproducibility of VUE attenuation was high for all scanners, yet inter-scan variation of VUE attenuation was influenced by contrast enhancement, showing greatest magnitude and discrepancy between scanner types in vessels and the kidneys. KEY POINTS: • We found that 94.9% of attenuation measurements on virtual unenhanced images were reproducible for rapid kV switching DECT, 93.8% for dual-layer detector DECT, and 90.6% for dual-source DECT. • Inter-scan variation of attenuation in virtual unenhanced images was comparable between the three scanner types in the liver and fat, whereas inter-scan variation in the spleen, kidneys, portal vein, and aorta showed significant differences between scanner types (p < 0.05). • Inter-scan attenuation differences in contrast-enhanced images significantly influenced inter-scan differences in virtual unenhanced attenuation (p < 0.001, t-ratio: 4.34), suggesting a residual impact of contrast enhancement differences between examinations.
OBJECTIVES: The accuracy of virtual unenhanced (VUE) images has been extensively investigated, yet data on their longitudinal reproducibility is limited. The study purpose was to evaluate the longitudinal reproducibility of VUE attenuation measurements on three different dual-energy CT (DECT) scanner types. METHODS: A total of 137 patients with repeated abdominal DECT either on a rapid kV switching (rsDECT; n = 46), a dual-layer detector (dlDECT; n = 43), or a dual-source scanner (dsDECT; n = 48) were retrospectively included. Attenuation was measured on VUE and corresponding contrast-enhanced images in the liver, spleen, kidneys, aorta, portal vein, and fat. Longitudinal reproducibility was evaluated by calculating the absolute inter-scan differences (HU) and the inter-scan variation (%). Measurement pairs with differences ≤ 10 HU were considered reproducible. Influence of contrast-enhanced attenuation on VUE reproducibility was analyzed using linear regression. RESULTS: The scanner-specific cohorts showed similar age (p-range: 0.35-0.99), sex (p-range: 0.68-1), body weight (p-range: 0.26-0.87), body diameter (p-range: 0.34-0.76), and inter-scan time (p-range: 0.52-0.83). In total, 94.9% of VUE measurements were reproducible for rsDECT, 93.8% for dlDECT, and 90.6% for dsDECT. Overall inter-scan variation was lowest in fat (4.0 (1.7-8.2)%) and highest in tissues with high contrast enhancement: the aorta (13.3 (4.6-21.3)%), portal vein (10.8 (5.7-19.8)%), and kidneys (10.7 (3.9-18.0)%). Significant differences in inter-scan variation were found between the scanner types for the aorta, portal vein, kidneys, and spleen. Inter-scan differences in contrast-enhanced attenuation significantly influenced inter-scan differences in VUE attenuation (p < 0.001; t-ratio: 4.34). CONCLUSIONS: Longitudinal reproducibility of VUE attenuation was high for all scanners, yet inter-scan variation of VUE attenuation was influenced by contrast enhancement, showing greatest magnitude and discrepancy between scanner types in vessels and the kidneys. KEY POINTS: • We found that 94.9% of attenuation measurements on virtual unenhanced images were reproducible for rapid kV switching DECT, 93.8% for dual-layer detector DECT, and 90.6% for dual-source DECT. • Inter-scan variation of attenuation in virtual unenhanced images was comparable between the three scanner types in the liver and fat, whereas inter-scan variation in the spleen, kidneys, portal vein, and aorta showed significant differences between scanner types (p < 0.05). • Inter-scan attenuation differences in contrast-enhanced images significantly influenced inter-scan differences in virtual unenhanced attenuation (p < 0.001, t-ratio: 4.34), suggesting a residual impact of contrast enhancement differences between examinations.
Entities:
Keywords:
Contrast media; Reproducibility of results; Tomography, X-ray computed
Authors: Brian R Herts; Stuart G Silverman; Nicole M Hindman; Robert G Uzzo; Robert P Hartman; Gary M Israel; Deborah A Baumgarten; Lincoln L Berland; Pari V Pandharipande Journal: J Am Coll Radiol Date: 2017-06-23 Impact factor: 5.532
Authors: Richard M Gore; Perry J Pickhardt; Koenraad J Mortele; Elliot K Fishman; Jeanne M Horowitz; Claus J Fimmel; Mark S Talamonti; Lincoln L Berland; Pari V Pandharipande Journal: J Am Coll Radiol Date: 2017-09-18 Impact factor: 5.532
Authors: Anno Graser; Christoph R Becker; Michael Staehler; Dirk A Clevert; Michael Macari; Niko Arndt; Konstantin Nikolaou; Wieland Sommer; Christian Stief; Maximilian F Reiser; Thorsten R C Johnson Journal: Invest Radiol Date: 2010-07 Impact factor: 6.016
Authors: Matthias Lazar; Helmut Ringl; Pascal Baltzer; Daniel Toth; Christian Seitz; Bernhard Krauss; Ewald Unger; Stephan Polanec; Dietmar Tamandl; Christian J Herold; Michael Toepker Journal: Eur Radiol Date: 2020-04-03 Impact factor: 5.315
Authors: Carlo Nicola De Cecco; Anna Darnell; Napoleón Macías; Juan Ramón Ayuso; Sonia Rodríguez; Jordi Rimola; Mario Pagés; Angeles García-Criado; Marco Rengo; Andrea Laghi; Carmen Ayuso Journal: Invest Radiol Date: 2013-01 Impact factor: 6.016
Authors: Daniel I Glazer; Katherine E Maturen; Ravi K Kaza; Isaac R Francis; Nahid R Keshavarzi; Robert A Parker; Joel F Platt Journal: AJR Am J Roentgenol Date: 2014-08 Impact factor: 3.959
Authors: Kai Roman Laukamp; Simon Lennartz; Vivian Ho; Nils Große Hokamp; David Zopfs; Amit Gupta; Frank Philipp Graner; Jan Borggrefe; Robert Gilkeson; Nikhil Ramaiya Journal: Br J Radiol Date: 2020-01-02 Impact factor: 3.039