Artifact reduction from dental implants using virtual monoenergetic reconstructions from novel spectral detector CT

Nils Große Hokamp; K R Laukamp; S Lennartz; D Zopfs; N Abdullayev; V F Neuhaus; D Maintz; J Borggrefe

doi:10.1016/j.ejrad.2018.04.018

Artifact reduction from dental implants using virtual monoenergetic reconstructions from novel spectral detector CT

Eur J Radiol. 2018 Jul:104:136-142. doi: 10.1016/j.ejrad.2018.04.018. Epub 2018 Apr 27.

Authors

Nils Große Hokamp¹, K R Laukamp², S Lennartz², D Zopfs², N Abdullayev², V F Neuhaus², D Maintz², J Borggrefe²

Affiliations

¹ Institute of Diagnostic and Interventional Radiology, University Hospital Cologne, Cologne, Germany; Department of Radiology, University Hospitals Cleveland, Cleveland, OH, USA; Department of Radiology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA. Electronic address: nils.grosse-hokamp@uk-koeln.de.
² Institute of Diagnostic and Interventional Radiology, University Hospital Cologne, Cologne, Germany.

PMID: 29857859
DOI: 10.1016/j.ejrad.2018.04.018

Abstract

Objectives: Image quality in head and neck imaging is often severely hampered by artifacts arising from dental implants. This study evaluates metal artifact (MA) reduction using virtual monoenergetic images (VMI) compared to conventional CT images (CI) from spectral-detector computed tomography (SDCT).

Methods: 38 consecutive patients with dental implants were included in this retrospective study. All examinations were performed using a SDCT (IQon, Philips, Best, The Netherlands). Images were reconstructed as conventional images (CI) and as VMI in a range of 40-200 keV (10 keV increment). Quantitative image analysis was performed ROI-based by measurement of attenuation (HU) and standard deviation in most pronounced hypo- and hyperdense artifact, fat and soft tissue with presence of artifacts. Qualitatively, extent of artifact reduction, assessment of soft palate and cheeks were rated on 5-point Likert-scales by two radiologists. Statistical data evaluation included ANOVA and Wilcoxon-test with correction for multiple comparisons; interrater-agreement was determined by intraclass-correlation coefficient (ICC).

Results: The hypo- and hyperattenuating artifacts showed an increase and decrease of HU-values in VMI_high (CI/VMI_{200 keV}: -218.7/-174.4 HU, p = 0.1; and 309.8/119.2, p ≤ 0.05, respectively). Artifacts in the fat, as depicted by image noise did also decrease in VMI_high (CI/VMI_{200 keV}: 23.9/16.4, p ≤ 0.05). Qualitatively, hyperdense artifacts were decreased significantly in VMI ≥100 keV (e.g. CI/VMI_{200 keV}: 2(1-3)/3(1-5), p ≤ 0.05). Artifact reduction resulted in improved assessment of the soft palate and cheeks (e.g. CI/VMI_{200 keV}: 2(1-4)/3(1-5) and 2(1-5)/3(1-5), p ≤ 0.05). Overall interrater agreement was good (ICC = 0.77).

Conclusions: Virtual monoenergetic images from SDCT reduce metal artifacts from dental implants and improve diagnostic assessment of surrounding soft tissue.

Keywords: Artifact; Dental implant; Dual energy computed tomography; Virtual monoenergetic image.

MeSH terms

Adult
Aged
Aged, 80 and over
Artifacts*
Dental Implants*
Female
Head and Neck Neoplasms / diagnostic imaging
Humans
Male
Metals
Middle Aged
Phantoms, Imaging
Radiographic Image Enhancement
Radiographic Image Interpretation, Computer-Assisted / methods*
Reproducibility of Results
Retrospective Studies
Sensitivity and Specificity
Tomography, X-Ray Computed / methods

Substances

Dental Implants
Metals