Abdominal CT: an intra-individual comparison between virtual monochromatic spectral and polychromatic 120-kVp images obtained during the same examination

Yoshitake Yamada; Masahiro Jinzaki; Takahiro Hosokawa; Yutaka Tanami; Takayuki Abe; Sachio Kuribayashi

doi:10.1016/j.ejrad.2014.06.004

Abdominal CT: an intra-individual comparison between virtual monochromatic spectral and polychromatic 120-kVp images obtained during the same examination

Eur J Radiol. 2014 Oct;83(10):1715-22. doi: 10.1016/j.ejrad.2014.06.004. Epub 2014 Jun 21.

Authors

Yoshitake Yamada¹, Masahiro Jinzaki², Takahiro Hosokawa³, Yutaka Tanami⁴, Takayuki Abe⁵, Sachio Kuribayashi⁶

Affiliations

¹ Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: yamada@rad.med.keio.ac.jp.
² Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: jinzaki@rad.med.keio.ac.jp.
³ Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: snowglobe@infoseek.jp.
⁴ Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: tanami@rad.med.keio.ac.jp.
⁵ Center for Clinical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: tabe@z5.keio.jp.
⁶ Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: skuribay@med.keio.ac.jp.

PMID: 25015416
DOI: 10.1016/j.ejrad.2014.06.004

Abstract

Objectives: To compare quantitative and subjective image quality between virtual monochromatic spectral (VMS) and conventional polychromatic 120-kVp imaging performed during the same abdominal computed tomography (CT) examination.

Materials and methods: Our institutional review board approved this prospective study; each participant provided written informed consent. 51 patients underwent sequential fast kVp-switching dual-energy (80/140 kVp, volume CT dose index: 12.7 mGy) and single-energy (120-kVp, 12.7 mGy) abdominal enhanced CT over an 8 cm scan length with a random acquisition order and a 4.3-s interval. VMS images with filtered back projection (VMS-FBP) and adaptive statistical iterative reconstruction (so-called hybrid IR) (VMS-ASIR) (at 70 keV), as well as 120-kVp images with FBP (120-kVp-FBP) and ASIR (120-kVp-ASIR), were generated from dual-energy and single-energy CT data, respectively. The objective image noises, signal-to-noise ratios and contrast-to-noise ratios of the liver, kidney, pancreas, spleen, portal vein and aorta, and the lesion-to-liver and lesion-to-kidney contrast-to-noise ratios were measured. Two radiologists independently and blindly assessed the subjective image quality. The results were analyzed using the paired t-test, Wilcoxon signed rank sum test and mixed-effects model with Bonferroni correction.

Results: VMS-ASIR images were superior to 120-kVp-FBP, 120-kVp-ASIR and VMS-FBP images for all the quantitative assessments and the subjective overall image quality (all P<0.001), while VMS-FBP images were superior to 120-kVp-FBP and 120-kVp-ASIR images (all P<0.004).

Conclusions: VMS images at 70 keV have a higher image quality than 120-kVp images, regardless of the application of hybrid IR. Hybrid IR can further improve the image quality of VMS imaging.

Keywords: Abdomen; Multidetector computed tomography; Noise; Signal-to-noise ratio.

Publication types

Comparative Study
Research Support, Non-U.S. Gov't

MeSH terms

Aged
Contrast Media
Female
Humans
Iohexol
Male
Middle Aged
Prospective Studies
Radiographic Image Interpretation, Computer-Assisted / methods*
Radiography, Abdominal / methods*
Signal-To-Noise Ratio
Tomography, X-Ray Computed / methods*

Substances

Contrast Media
Iohexol