Cone Beam CT Imaging Artifacts and Incidental Findings

Introduction

• Presenter: Nyle, Dental and Maxillofacial Radiology Consultant, Leeds Dental Institute
• Aims:
  • Identify common Cone Beam CT (CBCT) artifacts
  • Understand artifact causes and minimization
  • Recognize common incidental findings in dental/maxillofacial regions

Artifacts in Cone Beam CT

Definition and Impact

• Artifacts: Structures in images not part of the actual object
• Degrade image quality, obscure or mimic pathology
• Importance of differentiating true object features from artifacts

Common Artifacts

Noise

• Random disturbances in the image
• Causes:
  • Quantum model: Less information increases noise
  • Scattered radiation
• Conventional CT vs. CBCT:
  • Conventional CT uses higher MA, reducing noise
  • CBCT is noisier due to lower MA
• Mitigation via pre and post collimation in conventional CT

Metal or Beam Hardening Artifact

• Dark/light bands from radio-dense objects, e.g., crowns, amalgam
• Can obscure or mimic pathology, such as caries
• Preparation: Remove metal objects (jewelry, dentures)
• Solution: Supplement with conventional radiographs

Movement Artifact

• Occurs during long scan times
• Can cause blurring, double outlines, mimic pathologies
• Scanner configurations (standing, seated, supine) affect occurrence
• Mitigation: Shorter scan times, patient instruction, scanner adjustments

Ring Artifact

• Caused by defective sites on the image receptor
• Results in dark rings on the image
• Solution: Regular maintenance and quality assurance

Aliasing Artifact

• Due to under-sampling
• Seen at the periphery of scanned volumes
• Mitigation: Centering ROI, using smallest field of view

Incidental Findings

Common Incidental Findings

• Caries: Not primary use of CBCT, often supplemented by radiographs
• Periodontal Disease: Bone loss, calculus deposits
• Tonsilloliths: Visible, especially with mandibular wisdom teeth
• Dense Bone Islands: May increase risk of root resorption

Other Radiographic Findings

• Bony Exostosis: Mandibular tori, potential Gardner syndrome
• Mucosal Thickening: Often indicates mucous retention cysts
• Retained Roots: Common finding
• Anatomical Features: Greater palatine groove, accessory maxillary ostia
• Nasal Septum Variations: Deviations, spurs, and turbinates
• Osteomas and Septal Perforation: Obstruct pathways or indicate diseases

Detection of Other Conditions

• TMJ Degeneration: Flattening, osteophyte formation
• Cervical Spine Abnormalities: Both degenerative and congenital
• Gubernacular Canal: Eruption pathways in impacted teeth

Soft Tissue Incidental Findings

• Salivary Stones
• Calcinosis Cutis
• Swelling Indications: Not primarily for soft tissue, but can indicate issues

Conclusion

• Importance of recognizing and understanding CBCT artifacts
• Awareness of incidental findings for clinical relevance
• Further Reading: Recommended papers for detailed study

End of Presentation