Evaluation of Virtual Monoenergetic Imaging Algorithms for Dual-Energy Carotid and Intracerebral CT Angiography: Effects on Image Quality, Artefacts and Diagnostic Performance for the Detection of Stenosis

Publication date: Available online 30 December 2017
Source:European Journal of Radiology
Author(s): Doris Leithner, Scherwin Mahmoudi, Julian L. Wichmann, Simon S. Martin, Lukas Lenga, Moritz H. Albrecht, Christian Booz, Christophe T. Arendt, Martin Beeres, Tommaso D'Angelo, Boris Bodelle, Thomas J. Vogl, Jan-Erik Scholtz
PurposeTo investigate the impact of traditional (VMI) and noise-optimized virtual monoenergetic imaging (VMI+) algorithms on quantitative and qualitative image quality, and the assessment of stenosis in carotid and intracranial dual-energy CTA (DE-CTA).Materials and methodsDE-CTA studies of 40 patients performed on a third-generation 192-slice dual-source CT scanner were included in this retrospective study. 120-kVp image-equivalent linearly-blended, VMI and VMI+ series were reconstructed. Quantitative analysis included evaluation of contrast-to-noise ratios (CNR) of the aorta, common carotid artery, internal carotid artery, middle cerebral artery, and basilar artery. VMI and VMI+ with highest CNR, and linearly-blended series were rated qualitatively. Three radiologists assessed artefacts and suitability for evaluation at shoulder height, carotid bifurcation, siphon, and intracranial using 5-point Likert scales. Detection and grading of stenosis were performed at carotid bifurcation and siphon.ResultsHighest CNR values were observed for 40-keV VMI+ compared to 65-keV VMI and linearly-blended images (P < 0.001). Artefacts were low in all qualitatively assessed series with excellent suitability for supraaortic artery evaluation at shoulder and bifurcation height. Suitability was significantly higher in VMI+ and VMI compared to linearly-blended images for intracranial and ICA assessment (P<0.002). VMI and VMI+ showed excellent accordance for detection and grading of stenosis at carotid bifurcation and siphon with no differences in diagnostic performance.Conclusion40-keV VMI+ showed improved quantitative image quality compared to 65-keV VMI and linearly-blended series in supraaortic DE-CTA. VMI and VMI+ provided increased suitability for carotid and intracranial artery evaluation with excellent assessment of stenosis, but did not translate into increased diagnostic performance.



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