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

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*

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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.

© 2013 by Lippincott Williams & Wilkins



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