From man to mouse

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From man to mouse
Human PET
human
microPET
mouse
rat
rat
infant monkey
mouse
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.. and back again
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Molecular(?) Imaging Modalities
Ultrasound
Optical (Bioluminescence, fluorescence)
CT
PET/SPECT
MRI
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Mechanic Collimation

• Resolution Efficiency inversely related

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Cardiac SPECT Images
Normal Myocardial Perfusion at stress and rest
Single Vessel Coronary Artery Disease at stress
and rest
SPECT image shows limited perfusion (horseshoe
shape rather than donut) especially under stress.
SPECT image exhibits full perfusion (bright,
donut shape) both at rest and under stress
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Performances not good enough for imaging
biological process in vivo in small animals (mice)
man
rat
Trying to Image apoptosis by proper tracer
(e.g.99mTcINIC-Annexin-V)
Geant 4 simulation
detector area 100 x 100 mm2
aorta 2 mm diameter
plaque size 0.5 x 1 x 4 mm3

• - pixellated CsI(Tl) (0.8 - 0.4 mm pitch)
• LaBr3 continuous (3 mm thick, different
  surface(s) treatment(diffusive vs absorptive)
• 6 x 6 mm2, 3 x 3 mm2, 1.5 x 1.5 mm2
• (PMT anode pixel size)

spatial resolution 500 ?m
system sensitivity 10 cps/?Ci
1000 counts/view/resol.elem. 1 plaque 10 mCi,10
resol.elem.
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Preliminary pinhole SPECT reconstruction results
from the CsI detector Images are displayed as MIP
(maximum-intensity-re-projections) animations
2 point sources
APOE mouse (kidneys shown)
Flood image
Sample projection image
Fig. 28 APOE mice
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Caratteristiche insufficienti per limaging di
processi biologici in piccoli animali (topi). E
necessario migliorare la risoluzione spaziale e
lefficienza
Human
Rat
Required spatial resolution
2 mm FWHM (8 mm3)
? 1 mm FWHM (? 1 mm3)
6 mm FWHM (200 mm3)
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