Rapid switching kVp dual energy CT: Value of reconstructed dual energy CT images and organ dose assessment in multiphasic liver CT exams Journal Article


Authors: Mahmood, U.; Horvat, N.; Horvat, J. V.; Ryan, D.; Gao, Y.; Carollo, G.; DeOcampo, R.; Do, R. K.; Katz, S.; Gerst, S.; Schmidtlein, C. R.; Dauer, L.; Erdi, Y.; Mannelli, L.
Article Title: Rapid switching kVp dual energy CT: Value of reconstructed dual energy CT images and organ dose assessment in multiphasic liver CT exams
Abstract: Purpose: Clinical applications of dual energy computed tomography (DECT) have been widely reported; however, the importance of the different image reconstructions and radiation organ dose remains a relevant area of investigation, particularly considering the different commercially available DECT equipment. Therefore, the purpose of this study was to assess the image reliability and compare the information content between several image reconstructions in a rapid-switching DECT (rsDECT), and assess radiation organ dose between rsDECT and conventional single-energy computed tomography (SECT) exams. Materials and methods: This Institutional Review Board-approved retrospective study included 98 consecutive patients who had a history of liver cancer and underwent multiphasic liver CT exams with rsDECT applied during the late arterial phase between June 2015 and December 2015. Virtual monochromatic 70 keV, material density images (MDI) iodine (-water) and virtual unenhanced (VUE) images were generated. Radiation dose analysis was performed in a subset of 44 patients who had also undergone a multiphasic SECT examination within 6 months of the rsDECT. Four board-certified abdominal radiologists reviewed 24–25 patients each, and a fifth radiologist re-evaluated all the scans to reach a consensus. The following imaging aspects were assessed by the radiologists: (a) attenuation measurements were made in the liver and spleen in VUE and true unenhanced (TUE) images; (b) subjective evaluation for lesion detection and conspicuity on MDI iodine (-water)/VUE images compared with the virtual monochromatic images/TUE images; and (c) overall image quality using a five-point Likert scale. The radiation dose analyses were evaluated in the subset of 44 patients regarding the following parameters: CTDIvol, dose length product, patient's effective diameter and organ dose using a Monte Carlo-based software, VirtualDose™ (Virtual Phantoms, Inc.) to 21 organs. Results: On average, image noise on the TUE images was 49% higher within the liver (p < 0.0001) and 48% higher within the spleen (p < 0.0001). CT numbers for the spleen were significantly higher on VUE images (p < 0.0001). Twenty-eight lesions in 24/98 (24.5%) patients were not observed on the VUE images. The conspicuity of vascular anatomy was considered better on MDI iodine (-water) Images 26.5% of patients. Using the Likert scale, the rsDECT image quality was considered to be satisfactory. Considering the subset of 44 patients with recent SECT, the organ dose was, on average, 37.4% less with rsDECT. As the patient's effective diameter decreased, the differences in dose between the rsDECT and SECT increased, with the total average organ dose being less by 65.1% when rsDECT was used. Conclusion: VUE images in the population had lower image noise than TUE images; however, a few small and hyperdense findings were not characterized on VUE images. Delineation of vascular anatomy was considered better in around a quarter of patients on MDI iodine (-water) images. Finally, radiation dose, particularly organ dose, was found to be lower with rsDECT, especially in smaller patients. © 2018 Elsevier B.V.
Keywords: dect; rapid-switching kv; virtual unenhanced
Journal Title: European Journal of Radiology
Volume: 102
ISSN: 0720-048X
Publisher: Elsevier B.V  
Date Published: 2018-05-01
Start Page: 102
End Page: 108
Language: English
DOI: 10.1016/j.ejrad.2018.02.022
PROVIDER: scopus
PMCID: PMC5918634
PUBMED: 29685522
DOI/URL:
Notes: Article -- Export Date: 1 May 2018 -- Source: Scopus
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MSK Authors
  1. Seth Stephen Katz
    22 Katz
  2. Scott R Gerst
    48 Gerst
  3. Kinh Gian Do
    260 Do
  4. Lawrence Dauer
    172 Dauer
  5. Yusuf E Erdi
    118 Erdi
  6. Usman Ahmad Mahmood
    48 Mahmood
  7. Yiming Gao
    19 Gao
  8. Natally Horvat
    105 Horvat
  9. Davinia Elizabeth Ryan
    7 Ryan