Transcript Vorlesung_15Oktober2013_Intro

Moderne nicht-invasive Methoden zur Erforschung
des menschlichen Gehirns
Priv.-Doz. Dr. Carsten Wolters
Dr.rer.nat. Harald Kugel
Dr.med. Gabriel Möddel
Priv.Doz. Dr. med. Christoph Kellinghaus
Vorlesung, 15.Oktober 2013
Outline
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General planning for this lecture (language? date/time? required
knowledge? Participants-Email-List!)
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Literature for this lecture
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Introduction to the lecture (Part 1)
Carsten Wolters, IBB, WWU Münster
Aktuelle Vorlesungsplanung
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15.Oktober: Vorbesprechung und Motivation (Wolters)
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22.Oktober: Einführung Magnetresonanztomographie (MRT) (Kugel)
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29.Oktober: Medizinische Grundlagen zur Elektro- (EEG) und Magnetoencephalography (MEG) (Wolters)
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5.Nov.: Mathematisch-physikalische Modellierungsgrundlagen zu EEG und MEG, Teil 1 (Wolters)
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12.Nov.: Mathematisch-physikalische Modellierungsgrundlagen zu EEG und MEG, Teil 2 (Wolters)
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19.Nov.: Grundlagen von Epilepsie und EEG (Kellinghaus)
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26.Nov.: Epileptische Anfälle und ihre Behandlung (Kellinghaus)
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3.Dez.: Registrierung von MRT: Teil 1 (Wolters)
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10.Dez3.: Registrierung von MRT: Teil 2 (Wolters)
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17.Dez.: Segmentierung von MRT (Wolters)
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7.Jan.: Mathematik des EEG/MEG Vorwärtsproblems, Teil 1 (Wolters)
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14.Jan.: Mathematik des EEG/MEG Vorwärtsproblems, Teil 2 (Wolters)
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21.Jan.: Mathematik des EEG/MEG inversen Problems, Teil 1 (Wolters)
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28.Jan.: Mathematik des EEG/MEG inversen Problems, Teil 2 (Wolters)
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4.Feb.: Epilepsiechirurgie, Teil 3 (Möddel)
Carsten Wolters, IBB, WWU Münster
Outline
•
Literature for this lecture
•
Introduction to the lecture (Part 1)
Carsten Wolters, IBB, WWU Münster
Literature for this lecture
• Lecture webside:
http://www.sci.utah.edu/~wolters/LiteraturZurVorlesung/
Carsten Wolters, IBB, WWU Münster
Outline
•
Literature for this lecture
•
Introduction to the lecture (Part 1)
Carsten Wolters, IBB, WWU Münster
Basics of clinical EEG and MEG
Carsten Wolters, IBB, WWU Münster
Electro- (EEG) and Magneto-encephalography (MEG)
275 channel axial gradiometer whole-cortex MEG
128 channel EEG
Carsten Wolters, IBB, WWU Münster
[Gazzaniga, Ivry & Mangun, Cognitive Neuroscience, 2nd ed., W.W.Norton & Company, 2002]
Spatial and temporal resolution of brain
imaging methods
Carsten Wolters, IBB, WWU Münster
Grundlagen klinischer EEG
und MEG Anwendungen
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EEG ist Standard in der klinischen Praxis
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MEG ist kostenintensiv (Gerätekosten, Wartung,
Heliumkühlung…)
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Datenauswertung ist komplex (wie auch für EEG, fMRT, …)
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In Deutschland bisher keine Vergütung durch die
Krankenkassen
=> Warum also MEG?
Carsten Wolters, IBB, WWU Münster
Grundlagen - MEG
• MEG registriert nicht-invasiv
magnetische Felder neuronaler
Aktivität
• Ähnlich dem EEG: Ableitung
neuronaler Aktivität
• MEG und EEG messen Aktivität
derselben Generatoren
• PET oder fMRT: Indirekte
Erfassung neuronaler Aktivität
4D Neuroimaging, San Diego, CA, USA
Carsten Wolters, IBB, WWU Münster
Magnetische Abschirmkammer
Carsten Wolters, IBB, WWU Münster
MEG Interna
Carsten Wolters, IBB, WWU Münster
Erfassung des magnetischen Flusses
Magnetometer
Superconducting quantum
interference device
(SQUID)
Axiales Gradiometer
Planares Gradiometer
Papanicolaou (Ed.): Clinical
Magnetoencephalography and Magnetic Source
Imaging
Carsten Wolters, IBB, WWU Münster
[Lanfer, diploma thesis, 2007]
MEG-System am IBB, Uni Münster
Finite Elemente Knoten für die MEG Sensor-Beschreibung
Carsten Wolters, IBB, WWU Münster
Epileptic activity as measured
with EEG and MEG
Carsten Wolters, IBB, WWU Münster
Source analysis in presurgical epilepsy diagnosis
• 0.5%-1% of world population suffers from epilepsy
• 70-80% of patients successfully treated with drugs
• For those who are still pharma-resistent after 2-3 drugs
– Probability of success of a further different drug: 6% (Wiebe et al 2001)
– Probability of success of a surgical treatment: 50% (Wiebe et al 2001)
• Indispensable prerequisite for surgery: Focal epilepsy->Localization
– Gold standard: Video-monitoring and visual inspection of the EEG (Wilson
1996)
– MRI: Identification of an underlying lesion
– PET and Neuropsychology: Localization of a functional deficit
– Source analysis of
• EEG seizure (ictal) activity (Plummer et al., 2008)
• EEG/MEG interictal activity: “irritative zone” (Stefan et. al., 2003)
Carsten Wolters, IBB, WWU Münster
Epileptic spikes in
EEG and MEG
Clear spike in EEG
Nearly no/no signal in MEG
Carsten Wolters, IBB, WWU Münster
Epileptic spikes in
EEG and MEG
Clear spike in EEG
Nearly no/no signal in MEG
 Deep source
 Strongly radially oriented source
Carsten Wolters, IBB, WWU Münster
Sensitivity for radial and tangential sources
• MEG registers mainly
tangential source
components: Sulci-walls:
tangential pyramidal cells
-> High amplitudes
• „Diagonal“ orientation
-> Medium amplitude
• Radial sources hardly
produce an MEG: Depth and
crown of sulci: radial
pyramidal cells
-> Low contribution
Carsten Wolters, IBB, WWU Münster
Epileptic spikes in
EEG and MEG
Clear signal in MEG,
poor signal in EEG
Explanation?
Carsten Wolters, IBB, WWU Münster
Sensitivity
• Sensitivity EEG > MEG
in deep areas
• But: Sensitivity MEG > EEG
in superficial areas
Goldenholz et al., 2009
Carsten Wolters, IBB, WWU Münster
Spikes in EEG and MEG
What should we use?
MEG instead of EEG?
Only EEG?
Iwasaki et al., 2005
Carsten Wolters, IBB, WWU Münster
Combined EEG and MEG
275 channel axial gradiometer whole-cortex MEG
128 channel EEG
Carsten Wolters, IBB, WWU Münster
Source analysis of interictal spikes in
presurgical epilepsy diagnosis
Carsten Wolters, IBB, WWU Münster
[Wolters & Kellinghaus, 2006]
Averaged interictal EEG spikes
Measure EEG and/or MEG
Carsten Wolters, IBB, WWU Münster
[Wolters & Kellinghaus, 2006]
Results of combined EEG/MEG dipole fit
EEG data and (transparent) cortex
MEG data and (transparent) cortex
Inverse method: Single current dipole
Carsten Wolters, IBB, WWU Münster
[Wolters & Kellinghaus, 2006]
Results of combined EEG/MEG L1 norm current
density reconstruction
EEG data and (nontransparent) cortex
MEG data and (nontransparent) cortex
Inverse method: L1 norm current density
Carsten Wolters, IBB, WWU Münster
Source analysis of seizure (ictal) spikes in
presurgical epilepsy diagnosis
Carsten Wolters, IBB, WWU Münster
[Gazzaniga, Ivry & Mangun, Cognitive Neuroscience, 2nd ed., W.W.Norton & Company, 2002]
Typical EEG signals
Gamma(30-70Hz): Starke Konzentr., Lernphase
Beta (14-30Hz): Hellwach, gute Intelligenzleistung
Alpha (8-13Hz): Entspannte Wachheit
Theta (4-7Hz): Leichte Schlafphasen
Delta (0.3-3.5Hz): Traumlose Tiefschlafphase
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
EEG Preprocessing
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
T1 MRI segmentation
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
FE mesh generation
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
Brain conductivity anisotropy modeling
Original DTI data
FA map after registration
FA map on T1-MRI
Effective medium approach model (DTI <-> CTI):
Model DTI<->Conductivity Tensor Image (CTI) [Tuch et al., Ann. NYAS, 1999]
Linear model DTI<->CTI [Tuch et al., PNAS, 2001]
Validation of DTI<->CTI model in silk yarn phantom [Oh et al., ISMRM, 2006]
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
Presurgical EEG source analysis
Goal function scan
(Mosher, 1992; Knösche, 1997)
MNLS
(Hämäläinen & Ilmoniemi, 1984)
sLORETA
(Pascual-Marqui, 2002)
Dipole fit
(Scherg and von Cramon, 1985)
Result: Behind the lesion in lateral
premotor cortex
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
Validation: Intracranial EEG (iEEG)
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
CT and iEEG electrode positions
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
Validation result (localization)
iEEG peaking electrodes
sEEG Dipole fit result
Carsten Wolters, IBB, WWU Münster
[Rullmann, Anwander, Dannhauer, Warfield, Duffy & Wolters, NeuroImage, 44(2), 2009]
Validation result (orientation)
sEEG dipole fit result: Source orientation away from the lesion towards
the epileptogenic tissue (Salayev et al., 2006; Plummer et al., 2008)
Carsten Wolters, IBB, WWU Münster
Thank you for your attention!
Carsten Wolters, IBB, WWU Münster