nuclear imaging of the human brain
TRANSCRIPT
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Nuclear imaging of the human brain
Steven Laureys
Coma Science GroupCyclotron Research Centre & Neurology Dept.University of Liège, Belgium
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Neuroimagingstructurefunction
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Neuroimaging: Modalities
Laureys et al Brain imaging In: Biological PsychiatryEd D’haenen, den Boer, Willner, John Wiley & Sons 2002 155-166
Structural– Computerized Tomography (CT)– Magnetic Resonance Imaging (MRI)
Functional– Positron Emission Tomography (PET)– Single Photon Emission CT (SPECT)– functional MRI (fMRI)– MR spectroscopy– EEG & Event-Related Potentials (ERP)– Magnetoencephalography (MEG)– near infrared spectroscopy (NIRS)
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Structure versus function
Laureys et al Brain imaging In: Biological PsychiatryEd D’haenen, den Boer, Willner, John Wiley & Sons 2002 155-166
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Angelo Mosso & Bertino
Forarm
Brain
“Pulsometer”
Frontalskull defect
Taken from Posner & Raichle, Images of Mind
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John Fulton & Walter K
Rest
Reading
occipitalskull defect over arterio-venous malformation
« It was not difficult to convince ourselves that when the patient suddenly began to use his eyes after a prolonged period of rest in a dark room, there was a prompt and noticeable increase in the intensity of his bruit… Activity of his other sense organs, moreover, had no effect upon his bruit. »
“Bruitometer”
Brain, 1828
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Positron Emission Tomography
http://en.wikipedia.org/wiki/Positron_emission_tomography
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disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
[18F]2-fluoro-2-deoxyglucose
FDG
in plasma
FDG
in tissueFDG-6-P
in tissue
k1
k2
k3
(k4 )
Three compartment model
k = rate constant fluorodeoxyglucose
FDG-6-phosphate
intracellular hexokinase
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PET - fMRI
6 mm30 s
2-5 mm5-8 s
Hemodynamic imaging
H215O PET
1-3 mm1 s
fMRI BOLD
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PET - fMRI PET radiotracers
Dopamine
Benzodiazepine
Serotonin
Histamine
Muscarinic cholinergic
Amyloid, Protein kinase C, monoamine oxidase...
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Statistical parametric mapping
www.fil.ion.ucl.ac.uk/spm
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Imaging consciousness
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Terry Schiavo °1963, vegetative 1990, † 2005
Neuroimaging of consciousness
« Beyond any doubt whatsoever, Terri is in a vegetative state »- Ronald Cranford MD, Neurology, Minneapolis, MN
« There is a great likelihood that Terri is in a minimally conscious state »- William Cheshire MD, Neurology, Mayo Clinic, Jacksonville, FL
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Disorders of consciousness
Laureys, Scientific American, 2007
PermanentMinimally Conscious
State
?
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Blink and you live
Laureys et al., Progress in Brain Research, 2005
disorders of consciousness | clinical evaluation | electrophysiology | neuroimaging | ethics & quality of life | conclusion
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Functional neuroimagingresting brain functionbrain activation studies
passive paradigmsactive paradigms
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Neuroimaging
www.comascience.orgLaureys, Owen & Schiff, Lancet Neurology, 2004 (sleep data from Pierre Maquet; anesthesia data from Mike Alkire)
disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Resting metabolism
FDG-PET
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disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Rudolf et al. Lancet 2000
11C-flumazenil PET
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disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Laureys, Maquet, Moonen, Encyclopedia of Neuroscience, 2007
Global metabolism
FDG-PET
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disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Laureys et al, New Encyclopedia of Neuroscience (Ed.) Larry Squire, in press
Regional changes
n=60
FDG-PET
www.comascience.orgLaureys, Owen and Schiff, Lancet Neurology, 2005
disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Consciousness area ?
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HMPAO-SPECT
Ictal-interictal P<0.01
Simple partial seizure n=6
Complex partial seizure n=8
Blumenfeld et al, Cerebral Cortex, 2004
Temporal lobe epilepsy
www.comascience.orgLaufs et al, Epilepsia 2006
Negative correlation with GSWD
Absence seizures
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Sleepwalking
Patient compared to 24 controls
Bassetti et al, Lancet 356 (2000) 484-5ECD-SPECT
Sleepwalking
www.comascience.orgSchnakers et al, JNNP in press
Pharmacological stimulation
amantadine amantadine
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Functional neuroimagingresting brain functionbrain activation studies
passive paradigmsactive paradigms
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disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Do they feel pain ?
GRIMACINGNO RESPONSE AWAKENING
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disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Laureys, Nature Reviews Neuroscience, 2006
Vegetative is not brain dead
H215O-PET
www.comascience.orgLaureys et al., Neuroimage, 2002
disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
(n=15)
(n=15)
Cortical activation
www.comascience.orgLaureys et al., Neuroimage, 2002
disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Disconnected S1
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"…a (wo)men’s brain is a mystery...and even more so in this state."
Abla con Ella
Pedro Almodóvar
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disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Do they hear anything?
Laureys et al., Brain, 2000Boly et al, Archives of Neurology, 2004
www.comascience.orgLaureys et al., Neurology, 2004
Emotional processing
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Functional neuroimagingresting brain functionbrain activation studies
passive paradigmsactive paradigms
www.comascience.orgBoly et al, NeuroImage 36 (2007) 979-92
disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
TEN
NIS
NA
VIG
ATIO
NWhen thoughts become action
www.comascience.orgOwen, Coleman, Boly, Davis, Laureys and Pickard, Science, 2006
disorders of consciousness | behavioural evaluation | electrophysiology | neuroimaging | methods, ethics & quality of life | perspectives
Active paradigms
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Conclusions
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Conclusion
• Need for objective markers of consciousness in comatose states• PET
• quantify resting metabolism• neuro-receptor studies• markers of neuronal death & neuronal plasticity
• fMRI• ‘activation’ studies
• Vegetative state : disconnection syndrome with dysfunction of fronto-parietal network of “higher order” cortices
• Minimally conscious state : intact pain & emotional perception
• Much more research is needed
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