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Virtual Monoenergetic Images for Diagnostic Assessment of Hypodense Lesions Within the Liver

Semiautomatic Estimation of Window Settings Using Linear Models

Große Hokamp, Nils, MD*†‡; Obmann, Verena C., MD*†; Kessner, Rivka, MD*†; Gilkeson, Robert C., MD*; Gupta, Amit, MD*; Persigehl, Thorsten, MD; Haneder, Stefan, MD; Ramaiya, Nikhil, MD*

Journal of Computer Assisted Tomography: November/December 2018 - Volume 42 - Issue 6 - p 925–931
doi: 10.1097/RCT.0000000000000794
Abdominal Applications of Dual Energy CT

Objective The aim of the study was to establish the reference window settings for display of virtual monoenergetic images (VMIs) from spectral detector computed tomography when assessing hypodense liver lesions.

Methods In patients with cysts (n = 24) or metastases (n = 26), objective (HU, signal-to-noise ratio [SNR]) and subjective (overall image quality, lesion conspicuity and noise) were assessed. Furthermore, 2 readers determined optimal window center/width (C/W) for conventional images (CIs) and VMIs of 40 to 120 keV. Center/width were modeled against HUliv with and without respect to the keV level (models A and B).

Results Attenuation and SNR were significantly higher in low-keV VMIs and improved overall image quality and lesion conspicuity (P ≤ 0.05). Model B provided valid estimations of C/W, whereas model A was slightly less accurate.

Conclusions The increase in attenuation and SNR on low-keV VMIs requires adjustment of C/W, and they can be estimated in dependency of HUliv using linear models. Reference values for standard display of VMIs of 40 to 120 keV are reported.

From the *Department of Radiology, University Hospitals Cleveland Medical Center;

Department of Radiology, Case Western Reserve University, Cleveland, OH; and

Institute for Diagnostic and Interventional Radiology, University Hospital Cologne, Cologne, Germany.

Received for publication July 26, 2018; accepted August 3, 2018.

Correspondence to: Nils Große Hokamp, MD, Case Western Reserve University, Department of Radiology, 11000 Euclid Ave, Cleveland, OH 44106 (e-mail:

This study was partially supported by Philips Healthcare under a research agreement with University Hospitals Cleveland Medical Center and Case Western Reserve University.

N.G.H. is on the speaker's bureau of Philips Healthcare. The remaining authors declare no conflict of interest.

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

All authors have contributed substantially to this study according to the International Committee of Medical Journal Editors. All authors have read and approved the final version of this manuscript.

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