Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels.
OBJECTIVE
To evaluate optimal monoenergetic dual-energy computed tomography (DECT) settings for artefact reduction of posterior spinal fusion implants of various vendors and spine levels.


METHODS
Posterior spinal fusion implants of five vendors for cervical, thoracic and lumbar spine were examined ex vivo with single-energy (SE) CT (120 kVp) and DECT (140/100 kVp). Extrapolated monoenergetic DECT images at 64, 69, 88, 105 keV and individually adjusted monoenergy for optimised image quality (OPTkeV) were generated. Two independent radiologists assessed quantitative and qualitative image parameters for each device and spine level.


RESULTS
Inter-reader agreements of quantitative and qualitative parameters were high (ICC = 0.81-1.00, κ = 0.54-0.77). HU values of spinal fusion implants were significantly different among vendors (P < 0.001), spine levels (P < 0.01) and among SECT, monoenergetic DECT of 64, 69, 88, 105 keV and OPTkeV (P < 0.01). Image quality was significantly (P < 0.001) different between datasets and improved with higher monoenergies of DECT compared with SECT (V = 0.58, P < 0.001). Artefacts decreased significantly (V = 0.51, P < 0.001) at higher monoenergies. OPTkeV values ranged from 123-141 keV. OPTkeV according to vendor and spine level are presented herein.


CONCLUSIONS
Monoenergetic DECT provides significantly better image quality and less metallic artefacts from implants than SECT. Use of individual keV values for vendor and spine level is recommended.


CONCLUSIONS
• Artefacts pose problems for CT following posterior spinal fusion implants.                 • CT images are interpreted better with monoenergetic extrapolation using dual-energy (DE) CT.                 • DECT extrapolation improves image quality and reduces metallic artefacts over SECT.                 • There were considerable differences in monoenergy values among vendors and spine levels.                                  • Use of individualised monoenergy values is indicated for different metallic hardware devices.
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.
R
R
Guggenberger
S
S
Winklhofer
G
G
Osterhoff
G A
GA
Wanner
M
M
Fortunati
G
G
Andreisek
H
H
Alkadhi
P
P
Stolzmann
D016477:Artifacts; D006801:Humans; D008670:Metals / Q000737:chemistry*; D015588:Observer Variation; D019047:Phantoms, Imaging; D019736:Prostheses and Implants; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D011871:Radiology / Q000379:methods; D015203:Reproducibility of Results; D013123:Spinal Fusion / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D008670:Metals