fMRI (eBook)

Dedication 5
Contents 6
Contributors 8
Part I: Basics 11
Chapter 1 12
Introduction 12
Chapter 2 14
Neuroanatomy and Cortical Landmarks 14
2.1 Neuroanatomy and Cortical Landmarks of Functional Areas 14
2.1.1 Sensorimotor Cortex 14
2.1.1.1 Transverse Sections 14
2.1.1.2 Sagittal Sections 17
2.1.2 The Insula 18
2.1.2.1 Sagittal Sections 18
2.1.2.2 Transverse Sections 18
2.1.3 Speech Associated Frontal Areas 19
2.1.3.1 Transverse Sections 19
2.1.3.2 Sagittal Sections 19
2.1.4 Auditory Cortex and Speech Associated Temporo-Parietal Areas 20
2.1.4.1 Transverse Sections 20
2.1.4.2 Sagittal Sections 21
2.1.4.3 Coronal Sections 21
2.1.5 Visual Cortex 21
2.1.5.1 Sagittal Sections 21
References 21
Chapter 3 23
Spatial Resolution of fMRI Techniques 23
3.1 Introduction 23
3.2 Vascular Structure and Hemodynamic Response 23
3.3 Spatial Resolution of BOLD fMRI 24
3.4 Perfusion-Based fMRI Approaches 27
References 28
Chapter 4 30
The Electrophysiological Background of the fMRI Signal 30
4.1 Introduction 30
4.2 The Compound Neural Signal 31
4.3 The Passive Electric Properties of the Brain 32
4.4 The Neural Correlate of the BOLD Signal 34
4.5 The Coupling of Synaptic Activity and CBF 37
4.6 Conclusions 39
References 39
Chapter 5 41
High-Field fMRI 41
5.1 Introduction 41
5.2 Benefi ts and Limitations of High- and Ultra-High-Field MRI 41
5.3 Special Aspects of High-Field fMRI 42
5.4 Ultra-High Field fMRI and Possible Clinical Applications 44
References 47
Chapter 6 49
Press Button Solutions 49
6.1 Introduction 49
6.2 Material and Methods 49
6.2.1 Overview 49
6.2.2 Software Packages (in Alphabetic Order) 51
6.2.2.1 BrainLAB 51
6.2.2.2 NordicNeuroLab (NNL)/ NordicImagingLab (NIL) 51
6.2.2.3 PHILIPS 52
6.2.2.4 spm2 52
Results 52
6.3 Discussion/Future Aspects 54
References 54
Part II: Clinical Applications 55
Chapter 7 56
Preoperative Blood Oxygen Level Dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) of Motor and Somatosensory Function 56
7.1 Rationale for fMRI in Rolandic Neurosurgery 56
7.2 Review of Literature* 57
7.3 General Considerations 60
7.4 Diagnostic Aims 61
7.5 Selection of Candidates for Preoperative fMRI 61
7.6 Paradigms for Clinical Motor and Somatosensory fMRI 61
7.7 Preoperative fMRI in Patients with Rolandic Brain Tumors 64
7.7.1 Somatotopic Mapping of the Primary Motor Cortex (Standard Protocol) 64
7.7.2 Somatotopic Mapping of the Primary Somatosensory Cortex 67
7.7.3 Localization of the Precentral Gyrus in Patients with Paresis 67
7.8 Limitations and Pitfalls 69
References 70
Chapter 8 74
The Functional Anatomy of Speech Processing: From Auditory Cortex to Speech Recognition and Speech Production 74
8.1 Introduction 74
8.2 Hierarchical Organization of Auditory Cortex 74
8.3 STS Supports Phonological Aspects of Speech Recognition 74
8.4 Access to Conceptual-Semantic Information May Involve Middle Temporal Regions 76
8.5 Sensory Systems Participatein Speech Production 77
8.6 The Posterior Planum Temporale Supports Sensory-Motor Integration 77
8.7 Summary 78
References 79
Chapter 9 81
Use of fMRI Language Lateralization for Quantitative Prediction of Naming and Verbal Memory Outcome in Left Temporal Lobe Epilepsy Surgery 81
9.1 Use of fMRI for Predicting Naming Outcome 81
9.1.1 Measuring Language Lateralization 81
9.1.2 Predicting Naming Outcome 83
9.1.3 “Tailoring” Resections 84
9.2 Prediction of Verbal Memory Outcome 85
9.2.1 FMRI of the Medial Temporal Lobe 86
9.2.2 Medial Temporal Lobe FMRI as a Predictor of Memory Outcome 87
9.2.3 Language Lateralization as a Predictor of Verbal Memory Outcome 88
9.3 Conclusions 91
References 92
Chapter 10 98
Mapping of Recovery from Poststroke Aphasia: Comparison of PET and fMRI 98
10.1 The Principle of Activation Studies 98
10.2 Language Activation in Healthy Subjects 99
10.3 Poststroke Aphasia 101
10.4 Disturbance of Regional Metabolism and Flow vs. Severity and Persistence of Language Deficit 101
10.5 Changes in Activation Patterns vs. Recovery of Language Function 101
10.6 Effect of Treatment in Poststroke Aphasia 103
10.7 Combination of Repetitive Transcranial Magnetic Stimulation (rTMS) with Activated Imaging 104
10.8 Language Functionin Bra in Tumors 105
10.9 Hierarchical Organization for Recovery? 106
10.10 Conclusion 107
References 107
Chapter 11 110
Functional Magnetic Resonance-Guided Brain Tumor Resection 110
11.1 Introduction 110
11.2 Functional MRI Neuronavigation 111
11.3 Intraoperative Functional MRI 112
11.4 High Field Functional MRI 113
11.5 Materials and Methods 113
11.5.1 The Intraoperative MRI Suite 113
11.6 Functional MRI-Guided Tumor Resection 113
11.6.1 1.5 T Functional MRI-Guided Resection 113
11.6.2 3 T Functional MRI-Guided Resection 114
11.7 Results 114
11.7.1 Functional MRI at 1.5 T for the Treatment of Low Grade Glial Tumors 114
11.8 Functional MRI at 3 T 115
11.9 Discussion 116
11.10 Low Grade Gliomas 118
11.11 High Grade Gliomas 118
11.12 Other Tumors 119
11.13 Conclusions 119
References 121
Chapter 12 124
Direct Cortical Stimulation and fMRI 124
12.1 Introduction 124
12.2 Indications for Direct Cortical Stimulation and/or Functional Magnetic Resonance Imaging (fMRI): Patient Selection 125
12.3 Methods 125
12.3.1 Surgery Under Local Anesthesia: Awake Craniotomy 125
12.3.2 Stimulation 126
12.3.3 Intraoperative MRI 128
12.4 Practical Considerations 128
12.5 Results 128
12.6 Perspectives 128
References 129
Chapter 13 130
Imaging Epileptic Seizures Using fMRI 130
13.1 Introduction 130
13.2 Background 130
13.3 fMRI in Epilepsy 130
13.4 Classifi cation of Epileptic Seizures 131
13.5 Focal Epilepsies and the Concept of An “Epileptogenic Focus” 132
13.6 Neurovascular Coupling in Focal Epilepsy 132
13.7 fMRI Imaging of Focal Seizures 132
13.8 Benign Childhood Focal Epilepsies 133
13.9 Generalized Epilepsies 134
13.10 The Concept of Hypersynchrony in Primary Generalized Seizures 134
13.11 Neurovascular Coupling in Generalized Seizures 135
13.12 FMRI Imaging of Generalized Seizures 135
13.13 Continuous Seizures 136
13.13.1 Absence Status Epilepticus 136
13.13.2 Epilepsy Partialis Continua 136
13.14 Refl ex Seizures 137
13.14.1 Photosensitive Epilepsy 137
13.14.2 Reading Epilepsy 137
13.14.3 Writing Epilepsy 138
13.14.4 Musicogenic Epilepsy 138
13.15 The Future 138
13.15.1 The Concept of a Preictal State 138
13.15.2 Low Frequency Noise in BOLD 139
13.15.3 Is Perfusion Matched to CMRO2? 139
References 140
Chapter 14 143
Special Issues in fMRI-Studies Involving Children 143
14.1 Introduction 143
14.2 Planning a Paediatric Neuroimaging Study 143
14.3 Conducting a Paediatric Neuroimaging Study 144
14.4 Analyzing a Paediatric Neuroimaging Study 146
14.5 Conclusions 148
References 148
Chapter 16 156
Combining Transcranial Magnetic Stimulation with (f)MRI 156
16.1 Introduction 156
16.1.1 How Does TMS Excite Cortical Neurons? 156
16.1.2 Some Physical Aspects of Transcranial Magnetic Stimulation 157
16.1.3 Clinical and Neuroscientific Applications of TMS 157
16.1.4 Adverse Effects and Safety Precautions 158
16.2 Placement of the Coil Over the Cortical Target Area 158
16.3 Combinations of fMRI with TMS 159
16.3.1 Why Combine TMS with fMRI? 159
16.3.2 TMS in the MR Scanner During fMRI (Online TMS–fMRI Approach) 160
16.3.2.1 Methodological Issues 161
16.3.2.2 Applications of Interleaved TMS–fMRI 162
16.3.3 Offline combination of TMS and fMRI 164
16.3.3.1 TMS Following fMRI 164
16.3.3.2 fMRI Following TMS 164
16.4 Conclusion 166
References 166
Chapter 17 169
Clinical Magnetoencephalography and fMRI 169
17.1 Introduction 169
17.2 Clinical MEG Instrumentation 169
17.3 Magnetoencephalography and Electroencephalography Basic Biophysics 170
17.4 Analysis of MEG 170
17.4.1 Source Modeling 170
17.4.1.1 Equivalent Current Dipole 170
17.4.1.2 Distributed Solutions 171
Minimum Norm Estimate (MNE) 171
17.4.2 Combination with Other Imaging Technologies 171
17.5 Presurgical Mapping 171
17.5.1 Somatosensory Mapping 171
17.5.2 Motor Mapping 174
17.5.3 Auditory Cortex 174
17.5.4 Visual Cortex 174
17.5.5 Language Mapping 174
17.5.5.1 Functional Language Paradigms 175
17.5.5.2 Hemispheric Dominance for Language 175
17.5.5.3 Spatiotemporal Regional Language Mapping 175
17.6 Spontaneous Activity: Epileptic Spike Localization 176
17.7 MEG and fMRI: What’s the difference? 176
17.8 Conclusion 177
References 177
Index 179