Jeffrey M Politsky, MD FRCP(C) Northeast Regional Epilepsy Group Atlantic Neuroscience institute
Dec 24, 2015
Windows to the human brainWindows to the human brain
• Anatomical • Computerized X-ray Tomography (CT)• Magnetic Resonance Imaging (MRI)
• Functional, metabolic activity/blood flow• Positron Emission Tomography (PET)• Functional MRI (fMRI)• Near Infrared Spectroscopy (NIRS)
• Functional, information processing• Electroencephalography (EEG)• Magnetoencephalography (MEG)
Summary
3-T MRI V-EEG (at least 5 seizures separated
over time) PET MEG Functional Mapping Intra-cranial Monitoring
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MEGf MRI
CTMRI
PET
SPECTEEG
Temporal Resolution
Comparison of Methods
Comprehensive Epilepsy Center MEG
a technique for mapping brain activity by recording magnetic fields produced by inherently occurring electrical currents in the brain using arrays of SQUIDS (superconducting quantum interference devices);
Main Clinical Applications:○ Epilepsy Localization○ Functional brain mapping prior to brain tumor/lesion resection;
Clinical Research Applications: perceptual and cognitive brain processes; Psychiatric conditions, Autism Traumatic brain injury
Historical Development
1983by HUT4 channels30 mm in diameter(coverage: 7 cm2)Axial
1986by HUT7 channels93 mm in diameter(coverage: 68 cm2)Axial
1989by HUT24 channels125 mm in diameter(coverage:123 cm2)Planar
1992by Neuromag122 channelswhole head(coverage:1100 cm2)Planar12 Deliveries
1998by Neuromag306 channelswhole head(coverage:1220 cm2)Planar gradiometers &Magnetometers
The MEG (and EEG) signals derive from the net effect of ionic currents flowing in neuronal dendrites during synaptic transmission.