8/18/2011
Current and Future Clinical
Current and Future Clinical
Applications of Quantitative CT
Applications of Quantitative CT
Introduction
Quantitative Gray Scale (HU) in CT
Spatial Integrity in CT (length, area, volume)
Tumor Volume Assessment
Organ Volume Assessment
Future Applications
John M. Boone
Summary
Departments of Radiology and Biomedical Engineering
University of California, Davis
Radiography
t
I (t )

Io
e
  eff t
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Computed
Tomography
p
p (t )

t


ln 
 I o

  eff t 
e

Io
eff
HU
p

1000
 p



w
w 


Current and Future Clinical
Applications of Quantitative CT
Introduction
Quantitative Gray Scale (HU) in CT
Spatial Integrity in CT (length, area, volume)
Tumor Volume Assessment
Organ Volume Assessment
Future Applications
0.04
spr
0.03
Summary
0.02
0.01
0.00
position
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No detected scatter:
p (t )
t



ln 
 I o
Io
e
  eff t



calibration
patient
With detected scatter:
p (t )

t '


 Io
ln 
 I o 

Io
Io
e
  eff t
Scatter to primary ratio (SPR) = 



calibration
Water reference SPR = 0, measurement SPR different
1%
2%
3%
4%
5%
patient
Water reference SPR = 5%, measurement SPR different
1%
2%
3%
4%
5%
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Water reference SPR = measurement SPR
soft tissue
1%
2%
3%
4%
5%
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Fluence (mm-2)

 E m in  ( E )
E m ax
 (E ) 

 t


exp 
80 kV
100 kV
120 kV
140 kV
D(E )
air
E dE
water
80 kV
100 kV
120 kV
140 kV
LAC coefficient
Fluence (mm-2)
I (t )
-1000
0
Hounsfield Unit
Beam Hardening impacts HU
beam hardening
adipose
120 kV, head bowtie
water
iodine
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126.6+3.7
30 – 50 CT scans at
the same location
316.5 +3.5
perfusion
0.71+2.5
-96.7+3.0
A. perfusion imaging
time to peak
enhancement
blood volume
B. computed parametric images
55.2+3.2
Current and Future Clinical
Applications of Quantitative CT
Introduction
Quantitative Gray Scale (HU) in CT
Spatial Integrity in CT (length, area, volume)
acquired data (sinogram)
Tumor Volume Assessment
Organ Volume Assessment
Future Applications
Summary
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ramp filter
ramp filter with roll-off
acquired data (sinogram)
Frequency (relative to Nyquist)
filtered data
filtered data
LSF(x)
CT volume element
LSF(x)
SSP(x)
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SSP(x)
Current and Future Clinical
Applications of Quantitative CT
Introduction
Quantitative Gray Scale (HU) in CT
Spatial Integrity in CT (length, area, volume)
Tumor Volume Assessment
Organ Volume Assessment
Future Applications
Summary
Quantitative Imaging Biomarkers Alliance
DCE-MRI
fMRI
PET
Volumetric CT
CT in COPD
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Influence of Slice Thickness
Influence of display field of view
DFOV
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right adrenal
COV (%)
Volume (ml)
Left adrenal
COV = 18.5%
CT Scan Number
Volume (ml)
Current and Future Clinical
Applications of Quantitative CT
Introduction
Quantitative Gray Scale (HU) in CT
Spatial Integrity in CT (length, area, volume)
Tumor Volume Assessment
Liver
Organ Volume Assessment
Pancreas
Future Applications
Spleen
R/L Adrenal
Summary
R/L Kidney
Lumbar 1
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207
149 patient scans
Men 48.4 years
Women 49.3
Liver
Pancreas
Spleen
R/L Adrenal
R/L Kidney
Lumbar 1
over 18,000 ROI’s
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ml
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Current and Future Clinical
Applications of Quantitative CT
Introduction
Quantitative Gray Scale (HU) in CT
Spatial Integrity in CT (length, area, volume)
Future Technology Developments
Faster Scanning
Iterative Reconstruction: Lower Dose
Iterative Reconstruction: Serial imaging
Tumor Volume Assessment
Photon Counting: Lower Electronic Noise
Organ Volume Assessment
PC Energy Discrimination: “Free” Dual Energy
Future Applications
Summary
Future Clinical Applications
Joint Motion Kinetics (knee, foot, hand, fingers)
CT guided surgery (JS)
Dementia / cognitive screening
New Contrast Agents (not just blood pool)
Current and Future Clinical
Applications of Quantitative CT
Introduction
Quantitative Gray Scale (HU) in CT
Spatial Integrity in CT (length, area, volume)
COPD / Lung Function Assessment
Tumor Volume Assessment
Visceral fat assessment
Organ Volume Assessment
Extremity Imaging (dose not an issue?)
Future Applications
Summary
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Summary
CT Gray Scale (HU) is quantitative
(However less so with modern systems)
Spatial Integrity is excellent
Temporal Accuracy is excellent
Radiation doses will decrease
CT has a strong role to play in future apps
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