Brain Imaging

A Guide for Clinicians

Paul C. Lebby

A novel color-coded system is used throughout this guide to assist the reader in identifying slice locations and orientations

The crosshairs formed by the color-coded reference lines optimize the reader's ability to identify primary anatomical structures or pathological markers and processes

Many images are presented in 2D and 3D formats

Description

Brain Imaging: A Guide for Clinicians is designed to provide a foundation of information necessary to those wishing to integrate brain imaging into their practice, or to those that currently review brain scans but have minimal formal training in neuroimaging. The guide covers a range of topics important to those using brain imaging, such as the strengths and weaknesses of the many different techniques currently available, the factors that may influence the use of imaging data, common pitfalls or artifacts that may be misleading to the clinician, the most appropriate techniques to use given a specific clinical question or condition, how to interpret information presented on a brain image, and also how many pathological conditions appear on a variety of brain scanning techniques or sequences. This guide also provides detailed information regarding the identification of primary brain regions, anatomical structures, systems or pathways using both two-dimensional and three-dimensional imaging techniques. A brain atlas is included using both CT and MRI sequences to facilitate the reader's ability to identify most primary brain structures. A novel color-coded system is used throughout this guide to assist the reader in identifying slice locations and orientations. Images with green borders are displayed in the axial plane, with the slice location being shown on other orthogonal image planes by a green line. Similarly, images with a red border are displayed in the coronal plane and those with a blue border are displayed using a sagittal plane; red and blue reference lines are displayed on orthogonal slices to identify the slice location. The crosshairs formed by the color-coded reference lines optimize the reader's ability to identify primary anatomical structures or pathological markers and processes.

This book is written in a manner to progress from a general description of the clinical use of brain images and the interpretation of brain scans, to more complex chapters involving neuroanatomy and imaging technology. Real life examples of clinical cases are integrated into all chapters of this guide. Brain Imaging: A Guide for Clinicians provides hundreds of images derived from traumatic and non-traumatic pathologies to provide the reader with examples of conditions most often seen in the clinic. PEARL-PERIL sections outline critical information for the clinician, along with many tables and charts designed to provide general information required when interpreting brain images.

Brain Imaging

A Guide for Clinicians

Paul C. Lebby

Preface
Acknowledgments
Chapter 1: The Clinical Application of Brain Imaging
- Access to brain imaging
- Advantages of using brain imaging in the clinic
- Clues Regarding the Extent of an Injury
- Clues Regarding the Type of Injury
- Clues to the Location of Injury or Pathology
- Clues regarding prognosis and expected functional outcome
- Clues regarding the 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
Chapter 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
- The 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
- Look at the eyes
- Look at the bones of the skull
- Look at the bilateral structures that are commonly symmetrical
- Caution is warranted when using symmetry as a guide.
- Multiple pathologies can produce asymmetry of the brain
- Artifacts can produce asymmetry on an image
- Ventricular dilation and compression
- How much ventricular dilation can a person sustain without symptoms?
- Obstructive (non-communicating) Hydrocephalus
- Communicating Hydrocephalus
- Normal Pressure Hydrocephalus (hydrocephalus ex vacuo).
- Transependymal Edema
- Ventricular Asymmetry
- Steroid Use
- Guide to the General Appearance of Different Tissues on Brain Images
- Developmental changes evident on neuroimaging
- Myelination
- Temporal effects on the appearance of brain scans
- Caution when assessing atrophy
- Temporal Effects Due to Progression of an illness
- Know what the imaging should look like prior to viewing
- 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
Chapter 3: Imaging Based Neuroanatomy
- Reference Lines
- Primary anatomical landmarks
- Ventricles
- Meningeal Layers
- Dura and dural reflections (folds)
- Falx cerebri
- Tentorium cerebelli
- Dural Venous Sinuses
- Arachnoid Layer
- Arachnoid Cisterns
- Superior Cistern
- Interpeduncular or Basal Cistern
- Pia Mater
- White Matter Pathways
- Centrum Semiovale
- Corpus Callosum
- Coronal Orientation
- Sagittal Orientation
- Axial Orientation
- Pathology to the Corpus Callosum
- Cingulum
- Corona Radiata
- Internal Capsule
- The anterior limb of the internal capsule
- The genu of the internal capsule
- The posterior limb of the internal capsule
- Internal Capsule Injury
- Optic Tract and Radiations
- Optic Chiasm
- Optic Radiations (geniculostriate tract)
- Examples of visual field impairments
- Homonymous Right Hemianopia
- Homonymous Left Hemianopia
- Quadranopia: loss of approximately a quarter visual field
- Scotoma: visual field loss other than a half or quarter
- Forebrain
- Telencephalon
- Cerebral Cortex
- Lobes of the Brain
- Identifying areas of cortex on brain images
- Frontal and Parietal lobes
- Central Sulcus - Inferior Margin
- Central Sulcus - Middle Section
- Central Sulcus - Superior Margin
- Temporal Lobes
- Occipital Lobes
- Limbic system or lobe (Allocortex)
- Hippocampi (L: seahorse)
- Axial
- Coronal
- Sagittal
- Amygdala (L: almond)
- Axial
- Coronal
- Sagittal
- Mammillary Bodies
- Basal Ganglia
- Basal Ganglia on Brain Imaging
- LEVEL: Body of the lateral ventricles
- LEVEL: Foramen of Monro
- LEVEL: Third Ventricle
- Diencephalon
- Thalamus
- Thalami on brain imaging:
- Hypothalamus
- Hypothalamus on brain imaging:
- Epithalamus
- Pineal Body - "epiphysis "
- Pineal on brain imaging.
- Pituitary Gland - Hypophysis
- Pituitary on brain imaging.
- Adenomas-Suprasellar craniopharyngioma
- Mesencephalon
- Midbrain
- Red nuclei
- Substantia nigra (Latin: black substance)
- Substantia Nigra on brain imaging
- Reticular formation
- Central gray/periaqueductal gray
- Corpora quadrigemini (Latin: quadruplet bodies)
- Corpora quadrigemini on brain imaging
- General Location of the Midbrain Structures
- Hindbrain
- Metencephalon
- Pons
- Pons on brain imaging
- Cerebellum
- Myelencephalon
- Medulla oblongata
- Vascular System
- The internal carotid and vertebral artery distributions to the brain.
- Right and Left Internal Carotid Distribution
- Right and left vertebral artery and basilar distribution
- Circle of Willis
- Watershed area
- Appendix 3-1
Chapter 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)
- Absorption of x-rays
- Safety Concerns with CT
- Contrast CT Imaging
- Computed Tomography Angiography/Venography (CTA/CTV)
- Computed Tomography Ventriculography/Cisternography
- CT - Perfusion Studies
- CT Noise and Artifacts
- Quantum Noise
- Electronic Noise
- Computational Noise
- CT Artifacts
- Metallic Artifacts
- Streak Artifacts
- Angiography/Digital Subtraction Angiography (DSA)
- Phases of Angiography
- Three Dimensional Angiography
- MRI - Magnetic Resonance Imaging
- Safety Concerns of MRI
- Problems with higher strength magnet systems
- Three-Dimensional Imaging
- Reformatting of MRI images
- Re-slicing images using a thinner thickness and different slice angle
- Cutting windows into an image
- Signal Strength and Contrast on MRI
- MRI Noise
- MRI artifacts
- Motion Artifacts - MRI
- Metallic Objects
- MR Sequences
- T1 spin-lattice sequences
- 3D Ultrafast Gradient Echo T1 Images (FSPGR, BRAVO, MPRAGE)
- T2 spin-echo (spin-spin) sequences
- T2* "T2-star " spin-echo (spin-spin) sequences
- T2 Cube Sequences
- Proton Density (PD) or Spin-density sequences
- Fluid Attenuated Inversion Recovery (FLAIR) sequences
- Gradient Echo (GRE) sequences
- Gradient Echo - Echo-Planar Sequences
- Susceptibility Weighted MR Imaging (SWI)
- Propeller Sequences
- Fast imaging employing steady state acquisition (FIESTA) sequences
- MRI - Contrast Enhanced Imaging
- Magnetic Resonance Angiography (MRA)
- Two and Three-Dimensional Time of Flight Sequences (3D-TOF)
- Contrast Enhanced Magnetic Resonance Angiograpy/Venography (CE-MRA/MRV)
- Hybrid Brain Imaging
- Diffusion Weighted MRI (DWI)
- Apparent Diffusion Coefficient Maps (ADC)
- Temporal Changes to Diffusion Images
- How to use DWI and ADC maps to assess diffusion.
- Diffusion Tensor Imaging - Fractional Anisotropy and Tractography
- Structural FA maps
- Color-coded structural fractional anisotropy maps
- Color Structural FA Maps.
- DTI-Tractography
- Clinical application of diffusion tensor imaging
- DTI as a marker of axonal injury
- Cerebral Perfusion 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)
- Ictal MEG-MSI
- Limitations of MEG-MSE
- MEG-fMRI combination
- General Concerns regarding the clinical use of functional brain imaging
- A person is not a normalized population
- Is the "active " area a region of processing or a transmission hub?
- Local activation versus global or distributed activation
- Simple task paradigms are not the same as complex real-life activities
- Neuropathology can change metabolic functioning
- Functional imaging techniques are indirect measures of neural activity
- Neural activation functions at the sub-millisecond level
- The problem of Type I (false positive) Error
- The problem of nonindependence
- Time required to complete a study
- Interpretation of functional imaging data
- The benefit of using multiple functional imaging techniques for each patient
Chapter 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
- Diffuse Axonal Injury
- Hemorrhagic Contusions
- Contra Coup Injuries
- Common locations for hemorrhagic and non-hemorrhagic 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 asymmetric compression of the ventricles
- Loss of gray-white differentiation
- Blast injuries
- Imaging Changes Over Time Following Severe Traumatic Brain Injury
- Penetrating Injuries
- Penetration by Bone or Debris
- Gunshot Wounds
- Low Velocity Penetrating Injuries
- Low Velocity, Small Caliber Gunshot Wounds
- Low Velocity, Large Caliber Gunshot Wounds
- High velocity penetrating injuries
- High Velocity, Small Caliber Gunshot Wounds
- High Velocity, Large Caliber Gunshot Wounds
- Shotgun Injuries
- Non-Accidental Trauma (NAT)
- Suspected non-accidental trauma, but not non-accidental trauma
Chapter 6: Non-Traumatic Brain Injuries
- Infections Of The Brain
- Meningitis
- Encephalitis and Cerebritis
- Meningoencephalitis
- Abscess
- Empyema
- Stroke and Vascular Pathologies
- Imaging non-traumatic hemorrhagic strokes - cerebral vascular accident (CVA)
- Hemorrhagic Cavernomas
- Bleeding Disorders Resulting in Spontaneous Hemorrhage
- Non-hemorrhagic 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 non-enhancing tumor
- Diffuse, infiltrating and contrast-enhancing tumor
- Encapsulated non-enhancing 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
Chapter 7: Brain Atlas
Index
Bibliography

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