You could be reading the full-text of this article now if you...

If you have access to this article through your institution,
you can view this article in

The Effect of the Virtual Monochromatic Spectral Imaging for the Metallic Artifact and the Pulmonary Nodule Detection

Gyobu, Tomoko MD*; Honda, Osamu MD, PhD*; Kawata, Yutaka MD; Kikuyama, Ayano MD; Miki, Hiromu RT§; Yanagawa, Masahiro MD, PhD*; Sumikawa, Hiromitsu MD, PhD*; Koyama, Mitsuhiro MD, PhD; Tomiyama, Noriyuki MD, PhD*

Journal of Computer Assisted Tomography:
doi: 10.1097/RCT.0b013e31829e0164
Thoracic and Cardiovascular Imaging

Objectives: This study aimed to evaluate whether dual-energy computed tomography can reduce metal artifacts and improve detection of pulmonary nodules.

Methods: Twelve simulated nodules were randomly placed inside a chest phantom with a pacemaker. Then, dual-energy computed tomography was performed, and 5 virtual monochromatic images at 40, 50, 65, 100, and 140 keV were reconstructed with 5- and 0.625-mm slice thicknesses. Two independent observers assessed the metal artifact (3-point scale from 1, none, to 3, severe) and detection of the nodule (5-point scale from 1, definitely absent, to 5, definitely present). Statistical analysis was performed with a P value of less than 0.01 (0.05/5).

Results: With both slice thicknesses, the metallic artifact increased at 40 or 50 keV and decreased at 100 or 140 keV relative to that at 65 keV (P < 0.01). The nodule detection score was not significantly different between each kiloelectron volt level with the 0.625-mm slice thickness; however, the score was significantly worse at 40 keV compared to 65 keV (P < 0.01) with the 5-mm slice thickness.

Conclusions: High monochromatic energy images can reduce metal artifacts without a change in nodule detection score. Low monochromatic energy images increase metal artifacts and worsen nodule detection in thick slices.

Author Information

From the *Department of Radiology, Osaka University Graduate School of Medicine, Suita; †Department of Radiology, Osaka Rosai Hospital, Kita-ku, Sakai; ‡Department of Radiology, Osaka Furitsu Kyuseiki Sogo Iryo Center, Sumiyoshi-ku; §Department of Radiology, Osaka University Hospital, Suita; and ∥Department of Radiology, Osaka Medical College, Takatsuki, Osaka, Japan.

Received for publication March 18, 2013; accepted May 28, 2013.

Reprints: Tomoko Gyobu, MD, Department of Radiology, Osaka University Graduate School of Medicine, 2-2Yamadaoka, Suita, Osaka 565-0871, Japan (e-mail:

Conflicts of interest and source of funding: There is no conflict of interest.

© 2013 by Lippincott Williams & Wilkins