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Erschienen in: Abdominal Radiology 1/2017

28.07.2016

Comparison of virtual unenhanced CT images of the abdomen under different iodine flow rates

verfasst von: Yongrui Li, Ye Li, Alan Jackson, Xiaodong Li, Ning Huang, Chunjie Guo, Huimao Zhang

Erschienen in: Abdominal Radiology | Ausgabe 1/2017

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Abstract

Objective

To assess the effect of varying iodine flow rate (IFR) and iodine concentration on the quality of virtual unenhanced (VUE) images of the abdomen obtained with dual-energy CT.

Methods

94 subjects underwent unenhanced and triphasic contrast-enhanced CT scan of the abdomen, including arterial phase, portal venous phase, and delayed phase using dual-energy CT. Patients were randomized into 4 groups with different IFRs or iodine concentrations. VUE images were generated at 70 keV. The CT values, image noise, SNR and CNR of aorta, portal vein, liver, liver lesion, pancreatic parenchyma, spleen, erector spinae, and retroperitoneal fat were recorded. Dose–length product and effective dose for an examination with and without plain phase scan were calculated to assess the potential dose savings. Two radiologists independently assessed subjective image quality using a five-point scale. The Kolmogorov–Smirnov test was used first to test for normal distribution. Where data conformed to a normal distribution, analysis of variance was used to compare mean HU values, image noise, SNRs and CNRs for the 4 image sets. Where data distribution was not normal, a nonparametric test (Kruskal–Wallis test followed by stepwise step-down comparisons) was used. The significance level for all tests was 0.01 (two-sided) to allow for type 2 errors due to multiple testing.

Results

The CT numbers (HU) of VUE images showed no significant differences between the 4 groups (p > 0.05) or between different phases within the same group (p > 0.05). VUE images had equal or higher SNR and CNR than true unenhanced images. VUE images received equal or lower subjective image quality scores than unenhanced images but were of acceptable quality for diagnostic use. Calculated dose–length product and estimated dose showed that the use of VUE images in place of unenhanced images would be associated with a dose saving of 25%.

Conclusions

VUE images can replace conventional unenhanced images. VUE images are not affected by varying iodine flow rates and iodine concentrations, and diagnostic examinations could be acquired with a potential dose saving of 25%.
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Metadaten
Titel
Comparison of virtual unenhanced CT images of the abdomen under different iodine flow rates
verfasst von
Yongrui Li
Ye Li
Alan Jackson
Xiaodong Li
Ning Huang
Chunjie Guo
Huimao Zhang
Publikationsdatum
28.07.2016
Verlag
Springer US
Erschienen in
Abdominal Radiology / Ausgabe 1/2017
Print ISSN: 2366-004X
Elektronische ISSN: 2366-0058
DOI
https://doi.org/10.1007/s00261-016-0842-4

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