Application of Dual-source CT Virtual Single-energy Imaging to Remove Metal Artifacts in Pedicle Screws
Objective Dual-source CT virtual single-energy imaging(VMI)technique has significant application value in eliminating pedicle screw metal artifacts.In this study,we selected four different positions on the most severe level of artifacts,and explored the application value of dual source CT virtual single energy imaging technology in eliminating metal artifacts of pedicle screws from the aspects of artifact index and contrast-to-noise ratio.Methods Forty-eight patients who underwent dual-source CT examination of pedicle screws were included.Fourteen groups(60～190keV,interval 10keV)of monochromatic energy images and one group(140kVp)of mixed energy images were obtained.The CT values and standard deviations of four regions of interest around the metal implant and one fat region of interest at the same level were measured,and the artifact index and contrast signal-to-noise ratio were calculated.Subjective scoring was performed on the severity of artifacts and the clarity of the surrounding tissue of the metal.The difference of different image artifacts index,signal-to-noise ratio and subjective score were compared to evaluate the value of VMI in removing metal artifacts.Result The artifact index decreased and contrast signal-to-noise ratio increased of each region of interest with the increase of keV.When the energy level was 110-190keV,the artifact index was lower than that of 140 kVp image,and the difference was statistically significant(P＜0.05).The contrast signal-to-noise ratio of each region of interest at 110-190keV was higher than that of 140kVp hybrid energy image,and the difference was statistically significant(P＜0.05).The score of 110-150keV images was higher than that of 140kVp images,and the difference was statistically significant(P＜0.05)in terms of subjective evaluation.Conclusion Dual-source CT single energy imaging technology can effectively reduce the influence of metal artifacts after spinal screw internal fixation.Single-energy images with energy levels of 110 to 150 keV have low artifact indices and high contrast-to-noise ratios,and subjective evaluations show good artifact elimination,making them the best single-energy values for eliminating metal artifacts from pedicle screws.
Dual-source CTSingle Energy ImagingMetal ArtifactsPedicle Screw
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