30-Second Review

Spectral Imaging in CT

Different X-ray energies
↓
Different attenuation
↓
Material differentiation
↓
Spectral information

Key Outputs

Iodine Maps
Quantitative iodine distribution in mg/mL
VMI
Virtual Monoenergetic Images at selectable keV
VNC
Virtual Non-Contrast from contrast-enhanced data
Material Decomposition
Material-specific images from basis pairs

Clinical Applications

Vascular
  • Improved contrast-to-noise
  • Reduced stent/implant artefacts
Oncology
  • Tumour characterisation
  • Treatment response
Lung
  • Perfusion assessment
  • Pulmonary embolism
Renal Stones
  • Uric acid vs calcium
Bone
  • Bone removal for CTA
  • Gout detection

Advantages

  • Improved material differentiation
  • Quantitative iodine measurement
  • Reduced beam hardening and metal artefacts
  • Multiple image types from one acquisition
  • Potential dose reduction via VNC
  • Additional material-specific and quantitative information

Limitations

  • Noise — increased at low keV
  • Artefacts — residual around large metal
  • VNC limitations — not perfect in all tissues
  • Technology dependence — varies by manufacturer
  • Not automatically lower radiation dose
Different energies → Different attenuation → Material differentiation → Spectral images → Additional clinical information.