BOLD fMRI (eBook)

A Guide to Functional Imaging for Neuroscientists

Scott H. Faro, Feroze B. Mohamed (Herausgeber)

eBook Download: PDF

2010 | 2010
X, 294 Seiten
Springer New York (Verlag)
978-1-4419-1329-6 (ISBN)

Infos

Functional magnetic resonance imaging (fMRI) measures quick, tiny metabolic changes that take place in the brain, providing the most sensitive method currently available for identifying, investigating, and monitoring brain tumors, stroke, and chronic disorders of the nervous system like multiple sclerosis, and brain abnormalities related to dementia or seizures. This overview explains the principles of fMRI, scanning methodlogies, experimental design and data analysis, and outlines challenges and limitations of fMRI. It also provides a detailed neuroanatomic atlas, and describes clinical applications of fMRI in cognitive, sensory, and motor cases, translating research into clinical application.

Inhalt

Preface 6
Contents 8
Contributors 10
Part I: BOLD Functional MRI 12
1: Principles of Functional MRI 13
Introduction 13
Physiological Changes 14
Functional Imaging Contrasts 16
T1 Weighted fMRI 16
and T2 Based fMRI 19
Intravascular Component 19
Extravascular Component 22
Spin Echo versus Gradient Echo BOLD 24
Contrast-to-Noise Ratio 25
Spatial and Temporal Resolution of fMRI 27
Spatial Resolution 27
Temporal Resolution 27
Conclusions 28
References 29
2: fMRI Scanning Methodologies 33
General Overview 33
Spin-Echo and Gradient-Echo Imaging Methods 35
Spin-Echo Formation Mechanism 35
Spin-Echo Imaging Pulse Sequence 37
Contrast Characteristics of Spin-Echo Sequences 43
Vascular Effects 43
Flow Effects 45
Gradient-Echo Formation Mechanism 46
Gradient-Echo Imaging Pulse Sequence 48
Contrast Characteristics of Gradient-Echo Sequences 51
Vascular Effects 51
Inflow Effects 52
Echo Planar Imaging Methods 54
Echo Planar Imaging Pulse Sequences 55
Gradient Echo-Recalled EPI Sequence 58
Spin-Echo Recalled EPI Sequence 59
Spiral-Echo Planar Imaging Methods 60
References 63
3: Experimental Design and Data Analysis for fMRI 65
Introduction 65
Basic Types of Neuroimaging Inference 66
Manipulation of the Cognitive Process 68
Properties of the BOLD fMRI System That Impact Experimental Design 69
Different Temporal Structures of BOLD fMRI Experiments 71
Data Preprocessing 73
Distortion Correction 73
Slice Acquisition Correction 73
Motion Correction 74
Spatial Normalization 74
Spatial Smoothing 75
Statistical Analysis 75
References 79
4: Challenges in fMRI and Its Limitations 80
Introduction 80
MR Physics-Based Limitations in fMRI 81
Physics-Based Limitations on Spatial Resolution 81
SNR and Field Strength 83
Static Field Inhomogeneities 83
Effect of Acquisition TR 85
Physiological Factors Influencing Spatial Resolution 85
Physiological-Based Limitations/Constraints in fMRI 85
Blood Oxygenation Changes and Localization 86
Functional Spatial Limitations 86
Brain System Dependent Limitations 87
Draining Vein Problem 87
Initial Dip 88
Subject Movement 89
Other Physiological Changes Associated with Brain Activation 90
Threshold Effects and Localization 90
Temporal Resolution of the BOLD Response 90
Pulse Sequences for fMRI: Spatial/Temporal Resolution 92
Imaging Approaches to Other Physiological Measurements 95
Arterial Spin Labeling 95
Sensitivity 97
Summary 97
References 97
5: Clinical Challenges of fMRI 102
Introduction 102
A Brief History of Clinical Brain Mapping 103
Hemodynamic Basis of fMRI Maps 103
Technical Considerations 105
Field Strength 105
Scan Sequence and Susceptibility 106
Mapping the Oxy/Deoxyhemoglobin Signal 109
Study and Task Design 109
Task Selection 109
Practice Effects 111
Task Difficulty 112
Analysis 113
Within Subject Versus Group Analysis 114
Dependent Measures 115
Conjunction Analysis 116
Reproducibility 118
Applying fMRI to Clinical Planning 119
Significance of Signal Localization 119
Reliability of Signal Adjacent to Pathology 120
Relationship to Outcomes 121
Conclusions 121
References 121
Part II: fMRI Clinical Applications 126
6: Brain Mapping for Neurosurgery and Cognitive Neuroscience 127
Historical Milestones That Enable Imaging of Cortical Processes That Underlie Mental Events Using MRI 127
Development of Magnetic Resonance Imaging (MRI) to Visualize Living Brain Structure 130
The Development of fMRI 130
The BOLD Response 130
Hypothesis of Functional Specialization 132
Identification and Preservation of Cortical Areas Specialized for Essential Tasks 134
A Multifunction Task Battery 135
Healthy Volunteers and Patients 137
Sensitivity of Task Battery: Healthy Volunteers 137
Sensitivity of Task Battery: Surgical Population 137
Comparison of Task Sensitivity for Patients and Healthy Volunteers 139
Accuracy of Task Battery: Comparison with Intraoperative Electrophysiology 139
Comparison of fMRI, Wada, and Intraoperative Language Mapping 140
Comparison of fMRI and Visual Fields 140
Case Example 1: Motor and Language Mapping 140
Integrative Mapping of Sensory and Motor Functions 141
Interoperative Mapping of Language Functions 141
Postsurgical Status 142
Case Example 2: Language Mapping—Late Bilingual Patient 143
Case Example 3: Language Mapping—Early Bilingual Patient 144
Case Example 4: Motor Mapping 145
Determination of the Anatomy and Topography of Cortical Areas Specialized for Cognitive Tasks 148
Conservation of Effects versus Individual Differences: Generalizing the Results 148
Method of Cognitive Subtraction 149
Method of Cognitive Conjunction 149
Integration of Functionally Specialized Areas Associated with Cognitive Tasks: The Network Approach 151
Functional Neuroanatomy of Language Processes: A Large-Scale Network 151
Functional Neuroanatomy of Attention Processes: A Large-Scale Network 152
Tests of Cognitive Theory Based on Mapping of Neural Correlates 154
Functional Neuroanatomy of Working Memory: A Fixed- or Variable-Area Network 154
The N Back Task and a Test of a Cognitive Theory 154
Functional Neuroanatomy of Selective Attention: A Neurological Model of Cognitive Interference 155
The Stroop Task 155
Functional Neuroanatomy of Executive Processes: Separate or Combined Systems 157
The Go-No Go Task 159
Integration of Temporal and Spatial Information to Map Executive Processes 159
Integration of ERP and fMRI 160
Event-Related fMRI 160
The Oddball Task 161
The Functional Neuroanatomy of Very High Level Cognitive Processes 162
References 164
7: fMRI of Memory in Aging and Dementia 168
Episodic Memory 168
Age Related Changes in Episodic Memory 169
Episodic Memory in Alzheimer’s Disease and Related Conditions 175
Semantic Memory 178
Semantic Memory in Aging and Dementia 178
Working Memory 180
Working Memory in Aging and Dementia 181
Methodological Issues in the Use of fMRI in Aging and Dementia Research 182
Conclusion 183
References 184
8: fMRI of Language Systems: Methods and Applications 190
Some Proposed Clinical Applications of fMRI Language Mapping 190
Presurgical Applications 191
Prediction of Outcome in Aphasia 191
Diagnosis 192
Monitoring Treatment Effects 192
Some Theoretical Principles 192
Survey of Language Activation Protocols 194
Myth 1 194
Myth 2 194
Myth 3 195
Myth 4 195
Language Task: Passively Listening to Words or Sentences 198
Control Task: Rest 198
Language Task: Passively Listening to Words 198
Control Task: Passively Listening to Nonspeech 198
Language Task: Word Generation 199
Control Task: Rest 199
Language Task: Word Generation 199
Control Task: Reading or Repeating 199
Language Task: Visual Object Naming 199
Control Task: Rest 199
Language Task: Semantic Decision 200
Control Task: Sensory Discrimination 200
Language Task: Semantic Decision 200
Control Task: Phonological Decision 200
Language Task: Sentence or Word Reading 200
Control Task: Passively Viewing Letterstrings 200
Reliability, Validation, and Outcome Prediction Studies 202
Normative Studies 202
Test–Retest Reliability 204
Wada Comparisons 206
Comparisons with Cortical Stimulation Mapping 207
Prediction of Language Outcome 208
Future Applications: Use of fMRI Language Maps in Surgical Planning 209
References 212
9: fMRI Wada Test: Prospects for Presurgical Mapping of Language and Memory 221
Introduction 221
The IAT: History and Background 222
Description of a Standardized IAT Protocol 224
Replacement of the IAT with Functional Neuroimaging 225
fMRI Language Paradigms and the IAT 226
Case Examples of fMRI Language Activation 235
fMRI Memory Paradigms and the IAT 237
Case Examples of fMRI Memory Activation 241
Methodological Issues in Creating fMRI Paradigms to Replace the IAT 241
Technical Concerns 241
Clinical Concerns 244
Conclusions and Future Directions: Can We Replace the IAT with fMRI? 246
References 247
10: Cognitive Neuroscience Applications 254
Introduction 254
Inference in Functional Neuroimaging Studies of Cognitive Processes 255
Functional MRI as a Cognitive Neuroscience Tool 257
Temporal Resolution 259
Spatial Resolution 261
Issues in Functional MRI Experimental Design 263
Issues in Interpretation of fMRI Data 265
Statistics 265
Altered Hemodynamic Response 267
Types of Hypotheses Tested Using fMRI 269
Functional Specialization 269
Cognitive Theory 269
Functional Integration 270
Integration of Multiple Methods 271
Combined fMRI/Lesion Studies 271
Combined fMRI/Event-Related Potential Studies 273
Summary 274
References 274
Part III: Neuroanatomical Atlas 280
11: Neuroanatomical Atlas 281
Index 290

Produkt-Details

• Erscheint lt. Verlag: 3.7.2010
• Zusatzinfo: X, 294 p. 79 illus., 60 illus. in color.
• Verlagsort: New York
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Neurologie
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Psychiatrie / Psychotherapie
• Themenwelt: Medizinische Fachgebiete ► Radiologie / Bildgebende Verfahren ► Radiologie
• Themenwelt: Studium ► 2. Studienabschnitt (Klinik) ► Anamnese / Körperliche Untersuchung
• Schlagworte: clinical application • dementia • nervous system • Neuroscience • neurosurgery • Tumor
• ISBN-10: 1-4419-1329-7 / 1441913297
• ISBN-13: 978-1-4419-1329-6 / 9781441913296