Evaluation of different keV-settings in dual-energy CT angiography of the aorta using advanced image-based virtual monoenergetic imaging

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Web End = Int J Cardiovasc Imaging (2016) 32:137144 DOI 10.1007/s10554-015-0728-5

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Web End = Evaluation of different keV-settings in dual-energy CT angiography of the aorta using advanced image-based virtual monoenergetic imaging

Martin Beeres1 Jesko Trommer1 Claudia Frellesen1

Nour-Eldin A. Nour-Eldin1,3 Jan E. Scholtz1 Eva Herrmann2

Thomas J. Vogl1 Julian L. Wichmann1

Received: 26 April 2015 / Accepted: 27 July 2015 / Published online: 2 August 2015 Springer Science+Business Media Dordrecht 2015

Abstract To compare quantitative image quality in dual-energy CT angiography (DE-CTA) studies of the aorta using different virtual monoenergetic imaging (MEI) and advanced image-based virtual monoenergetic (MEI?) settings at varying kiloelectron volt (keV) levels. Fifty consecutive patients with clinically-indicated CT of the whole aorta to evaluate suspected aortic disease underwent DECTA on a third-generation dual-source CT scanner. Quantitative image quality indices were assessed. Contrast material, saline ush and ow rate were kept equal for

optimum comparability. DE-CTA MEI and MEI? series ranging from 40 to 100 keV (10-keV intervals) were reconstructed. Signal intensity, noise, signal-to-noise ratio and contrast-to-noise ratio (CNR) of multiple aortic segments were evaluated. Comparisons between the different MEI and MEI? datasets were performed. Three-hundred aortic segments total were evaluated. In the MEI? series the 40, 50 and 100 keV MEI? showed superior noise and CNR levels (?84, ?58, ?103 % on average; all p \ 0.05)

compared to MEI. However, signal intensity between MEI? and MEI at nearly all aortic segments showed no signicant difference (p [ 0.1). MEI? shows lower image noise compared to MEI, resulting in superior quantitative image quality, in particular at low keV levels (40 or 50 keV).

Keywords CT angiography Aorta Dual energy CT

Virtual monoenergetic imaging Image noise

Introduction

Dual-energy computed tomography (DECT) has gained increasing acceptance particularly in contrast-enhanced CT due to its post-processing opportunities. These techniques have been previously used to enhance image quality, improve diagnostic accuracy, and reduce the amount of contrast material or radiation exposure [15].

Virtual monoenergetic images (MEI) can be derived using a post-processing technique which allows for calculation of images at a...