Brain Imaging

Preface Acknowledgments Introduction

1: THE CLINICAL APPLICATION OF BRAIN IMAGING Access to Brain Imaging Advantages of Using Brain Imaging in the Clinic Clues Regarding Extent of Injury Clues Regarding Type of Injury Clues to Location of Injury or Pathology Clues Regarding Prognosis and Expected Functional Outcome Clues Regarding Time Course for Recovery Concrete Information for Families Limitations: What Neuroimaging Often Does Not Provide the Clinician Brain imaging does not measure a patient's functioning Brain imaging may not provide information about electrochemical processes Brain imaging does not provide direct visualization of microscopic injury Brain scans often do not provide information regarding the etiology of damage Brain scans do not treat the patient Showing Damage on Brain Images May Not be Recommended What to Do When the Patient or Family Members Ask to See the Brain Scans What to Request When Writing Orders for Brain Imaging Radiologist Reports Anatomy versus Functioning

2: VIEWING AND INTERPRETING BRAIN SCANS Orientation and Image Plane Axial or Horizontal Orientation Axial Reformatting with Varying Slice Angles Coronal Orientation Sagittal Orientation When Right Is Left and Left Is Right Basic Clinical Interpretation Appearance of Brain Tissue on Different Types of Brain Scans Interpreting Findings on a Variety of Scans Use several image types or sequences when assessing for pathology Know what to look for, but also be conservative in your interpretation Symmetry as a Guide to Interpreting Brain Scans Evaluating Head Position in the Scanner Exercise caution when using symmetry as a guide Ventricular Dilation and Compression How much ventricular dilation can a person sustain without symptoms? Obstructive (Noncommunicating) Hydrocephalus Communicating Hydrocephalus Normal-Pressure Hydrocephalus (Hydrocephalus ex vacuo) Transependymal Edema Ventricular Asymmetry Steroid Use Guide to General Appearance of Different Tissues on Brain Images Developmental Changes Evident on Neuroimaging Myelination Temporal Eff ects on Appearance of Brain Scans Use caution when assessing atrophy Temporal Eff ects due to Progression of an Illness Know what the imaging should look like before viewing it Diagnostic Pitfalls of Neuroimaging Being too Focused or Not Focused Enough Missing What Is Missing Missing Pathology in the Neutral Gray Stop Searching After Finding an Obvious Abnormality Consider All Possible Causes for a Particular "Pathological" Appearance Pitfalls of Knowing the Neuropathology and Anatomy of the Injury Quality of Brain Imaging DICOM Viewers Comparing Scans Acquired on Different Occasions Presentation of Simultaneous Images

3: IMAGING-BASED NEUROANATOMY Primary Anatomical Landmarks Ventricles Meningeal Layers Dura and Dural Reflections (Folds) Dural Venous Sinuses Arachnoid Layer Pia Mater White-Matter Pathways Centrum Semiovale Corpus Callosum Cingulum Corona Radiata Internal Capsule Optic Tract and Radiations Basic Anatomical Areas of the Brain Forebrain Telencephalon Mesencephalon Midbrain Hindbrain Vascular System Internal Carotid and Vertebral Artery Distributions to the Cortex Circle of Willis Watershed Area Appendix 3-1

4: BRAIN IMAGING TECHNIQUES Image Quality Spatial Resolution Contrast Resolution Noise What Type of Scan to Use? Types of Imaging Static Brain Imaging Ultrasound Computer Axial Tomography (CAT/CT) Angiography/Digital Subtraction Angiography (DSA) Magnetic Resonance Imaging (MRI) Hybrid Brain Imaging Diffusion-Weighted MRI (DWI) Diffusion Tensor Imaging-Fractional Anisotropy and Tractography Cerebral Perfusion-Weighted MRI (PWI) Magnetic Resonance Spectroscopy (MRS) Functional Brain Imaging Positron Emission Tomography (PET) Combined Positron Emission Tomography and CT (PET-CT) or MRI (PET-MRI) Single-Photon Emission Computed Tomography (SPECT) Functional Magnetic Resonance Imaging (fMRI) Magnetic Encephalopathy (MEG-MSI) General Concerns about Clinical Use of Functional Brain Imaging Benefits of Using Multiple Functional Imaging Techniques for Each Patient

5: NEUROIMAGING OF TRAUMATIC BRAIN INJURIES Focal Injury, Diffuse Injury, or a Combination? Post-Traumatic Hemorrhages Epidural Hemotoma/Hemorrhage (EDH) Subdural Hematoma/Hemorrhage (SDH) Examples of Subdural Hematomas/Hemorrhages Subarachnoid Hematoma/Hemorrhage Examples of Subarachnoid Hematomas/Hemorrhages Intraparenchymal Hemorrhages Petechial Hemorrhages Diff use Axonal Injury Hemorrhagic Contusions Contrecoup Injuries Common Locations for Hemorrhagic and Nonhemorrhagic Contusions Subcortical Hemorrhages Post-Traumatic Pneumocephalus Post-Traumatic Hypoxic Ischemic Encephalopathy Laminar Necrosis due to Hypoxic Ischemic Infarction Second-Impact Syndrome Intraventricular Hemorrhages Post-Traumatic Vasospasm Intracerebral Edema Midline Shift and Asymmetrical Compression the of Ventricles Loss of Gray-White Differentiation Blast Injuries Imaging Changes over Time Following SevereTraumatic Brain Injury Penetrating Injuries Penetration by Bone or Debris Gunshot Wounds Low-Velocity Penetrating Injuries High-Velocity Penetrating Injuries Shotgun Injuries Nonaccidental Trauma (NAT) Suspected Nonaccidental Trauma but Not Nonaccidental Trauma

6: NONTRAUMATIC BRAIN INJURIES Infections of the Brain Meningitis Encephalitis and Cerebritis Meningoencephalitis Abscess Empyema Stroke and Vascular Pathologies Imaging Nontraumatic Hemorrhagic Strokes-Cerebral Vascular Accident (CVA) Hemorrhagic Cavernomas Bleeding Disorders Resulting in Spontaneous Hemorrhage Nonhemorrhagic and Embolic Ischemic Strokes Blockage of Venous Flow Loss of Internal Carotid Flow Without Stroke-Related Symptoms Diffuse Hypoxic Encephalopathy Watershed Infarctions White-Matter Disorders Multiple Sclerosis (MS) Acute Disseminated Encephalomyalitis (ADEM) Toxic Damage to White Matter Neoplasm Diffuse, Infiltrating, and Nonenhancing Tumor Diffuse, Infiltrating, and Contrast-Enhancing Tumor Encapsulated Nonenhancing Cystic Tumor Encapsulated Contrast-Enhancing Tumor Hydrocephalus due to Tumor Growth Neurodevelopmental Disorders Cortical Dysplasia Agenesis of the Corpus Callosum (ACC) Polymicrogyria Anencephaly Holoprosencephaly Schizencephaly Multiple Neurodevelopmental Conditions Parasitic Disorders

7: BRAIN ATLAS Index Index of Clinical Examples