Evaluation of monoenergetic imaging to reduce metallic instrumentation artifacts in computed tomography of the cervical spine.
OBJECTIVE
Monoenergetic imaging with dual-energy CT has been proposed to reduce metallic artifacts in comparison with conventional polychromatic CT. The purpose of this study is to systematically evaluate and define the optimal dual-energy CT imaging parameters for specific cervical spinal implant alloy compositions.


METHODS
Spinal fixation rods of cobalt-chromium or titanium alloy inserted into the cervical spine section of an Alderson Rando anthropomorphic phantom were imaged ex vivo with fast-kilovoltage switching CT at 80 and 140 peak kV. The collimation width and field of view were varied between 20 and 40 mm and medium to large, respectively. Extrapolated monoenergetic images were generated at 70, 90, 110, and 130 kiloelectron volts (keV). The standard deviation of voxel intensities along a circular line profile around the spine was used as an index of the magnitude of metallic artifact.


RESULTS
The metallic artifact was more conspicuous around the fixation rods made of cobalt-chromium than those of titanium alloy. The magnitude of metallic artifact seen with titanium fixation rods was minimized at monoenergies of 90 keV and higher, using a collimation width of 20 mm and large field of view. The magnitude of metallic artifact with cobalt-chromium fixation rods was minimized at monoenergies of 110 keV and higher; collimation width or field of view had no effect.


CONCLUSIONS
Optimization of acquisition settings used with monoenergetic CT studies might yield reduced metallic artifacts.
Division of Neuroradiology, Department of Radiology and Medical Imaging, and.
Peter
P
Komlosi
Deborah
D
Grady
Justin S
JS
Smith
Christopher I
CI
Shaffrey
Allen R
AR
Goode
Patricia G
PG
Judy
Mark
M
Shaffrey
Max
M
Wintermark
D016477:Artifacts; D001858:Bone Nails; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D002858:Chromium Alloys; D006801:Humans; D019047:Phantoms, Imaging; D015900:Radiography, Dual-Energy Scanned Projection / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D013115:Spinal Canal / Q000000981:diagnostic imaging / Q000601:surgery; D013123:Spinal Fusion / Q000295:instrumentation; D014025:Titanium; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods / Q000592:standards*
D002858:Chromium Alloys; D014025:Titanium
FOV = field of view; GSI = Gemstone Spectral Imaging; cervical spine; dual-energy CT; image artifacts; kVp = peak kilovoltage; keV = kiloelectron volt; spine hardware; technique