230 likes | 249 Views
Jeffrey M Politsky, MD FRCP(C) Northeast Regional Epilepsy Group Atlantic Neuroscience institute. UPDATE in the DIAGNOSTIC APPROACH to EPILEPSY. Windows to the human brain. Anatomical Computerized X-ray Tomography (CT) Magnetic Resonance Imaging (MRI)
E N D
Jeffrey M Politsky, MD FRCP(C) Northeast Regional Epilepsy Group Atlantic Neuroscience institute UPDATE in the DIAGNOSTIC APPROACH to EPILEPSY
Windows 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
Comparison of Methods 1msec 1sec 1min 10min 1hour 10 SPECT EEG 8 6 PET Spatial resolution (mm) f MRI MEG 4 MRI 2 CT 0 0.0001 0.001 0.01 0.1 1 10 100 1000 10000 Temporal Resolution
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
Failed ideas Dual 14 (28)-Channel MEG System (1987)
Historical Development 1986 by HUT 7 channels 93 mm in diameter (coverage: 68 cm2) Axial 1983 by HUT 4 channels 30 mm in diameter (coverage: 7 cm2) Axial 1989 by HUT 24 channels 125 mm in diameter (coverage: 123 cm2) Planar 1992 by Neuromag 122 channels whole head (coverage: 1100 cm2) Planar 12 Deliveries 1998 by Neuromag 306 channels whole 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.