Dual energy CT - ZOL · 2020-02-27 · Dual-energy CT More information about tissues....
Transcript of Dual energy CT - ZOL · 2020-02-27 · Dual-energy CT More information about tissues....
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Dual energy CT
Dr. Pieter Marchal
Medische Beeldvorming ZOL
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Overzicht
• Inleiding
• Fysica 101
• Applicaties
• Voorbeelden
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Conventional (single energy) CT imaging
Scan acquisition
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Conventional (single energy) CT imaging
Image reconstruction
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Attenuation measurements (HU)
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Limitations of attenuation measurements
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Limitations of attenuation measurements
Variability in attenuation (HU) among SECT scanners: 10-25 HU
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Dual-energy CT
More information about tissues
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Dual-energy/spectral CT systems
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Dual-energy CT: material differentiation
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Material specific iodine images
Qualitative Iodine quantification
• Specific measurement of
tissue enhancement
• Increased tissue contrast
o Amplify subtle differences in
attenuation between normal
and abnormal tissues
o Regardless of the acquisition
time
• Images represent the mass
density (concentration)
• Opportunities
o Diagnosis
o Treatment planning
o Follow-up
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Processing
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DECT data sets
Virtual mono-chromatic images
• Simulated CT data sets resembling CT images generated from
mono-chromatic CT beam
• VMC images of lower energy (50-65 keV)
o Improve contrast between different tissues
o Enhance visualization of vessels and hyper vascular lesions
o Higher image noise and artifacts
• VMC images of higher energy
o Lower artifacts and reduced contrast between tissues
o Useful for reduction of metal artifacts
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Monochromatic images
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Monochromatic images
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DECT data sets
Virtual unenhanced images
• Image data sets are equivalent to non-contrast CT images
• Eliminate the need for true unenhanced acquisition thereby
reducing radiation dose
Material specific iodine images
• Image data sets show distribution of iodine in tissues
independent of background attenuation
• Provide a reliable representation of tissue enhancement
• Improved detection of lesion enhancement compared to HU
measurements
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VNC images
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Material specific iodine
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All cakes and ale?
Dose?
Metal artifacts?
Size?
Exam time?
Transmission time?
Education?
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Dose
• The radiation exposure required for DECT depends on the
technology used (dual source < single source)
• The aim is to use the same dose as would be used for a
single-energy examination
• Less number of scan phases
• Elimination of true non-contrast with VNC: -20%
• Elimination of true non-contrast and arterial phase: -64%
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Examples
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Kidney stones
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Kidney stones
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Kidney stones
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Kidney stones
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Gout
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Gout
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Gout
• Calcium and urate: marked difference in photoelectric
absorption
o Sensitivity: 78-100%
o Specificity: 89-100%
• Can calculate tophi volume
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Gout
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Lung embolism
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Lung embolism
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Lung embolism
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Conclusion
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Real?
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Dank u voor uw aandacht