Imaging of the Brain and Spinal Cord

Imaging of the Brain and Spinal Cord

• Different radiologic imaging modalities are used for brain and spinal cord
• Imaging helps identify anatomical structures
• Imaging aids in identifying common pathologic conditions

Diagnostic Imaging Modalities

• Cranial Ultrasound (CUS)
  • Uses sound waves to create images of the brain and cerebrospinal fluid
  • Valuable for evaluating the brain during the first year of life
  • Initial screening tool for infants
  • Complementary to CT and MRI
  • Safe, inexpensive, and portable
  • Can be repeated as necessary
  • Used to diagnose abnormal head circumference, hemorrhage, ventriculomegaly, vascular abnormalities, suspected hypoxic ischemic injury, congenital malformations, signs of central nervous system disorders, congenital or acquired brain infection, suspected or known head trauma, craniosynostosis, follow-up or surveillance of documented abnormalities, and screening before surgery.
• X-rays
  • Type of medical imaging using electromagnetic radiation
  • Penetrates the body, with different tissue densities absorbing varying amounts of X-rays
  • Creates an image on film or digital detector
  • Used to diagnose skull fractures, decalcification, birth defects, infections, pituitary tumors, and certain metabolic/endocrine disorders that cause skull bone defects.
  • Often used as a last resort in trauma imaging when CT is unavailable or contraindicated
  • Safe, inexpensive, and readily available
  • Limited soft tissue detail, with limited views often from just one or two angles. Exposure to ionizing radiation also a concern.
• CT (Computed Tomography)
  • Uses X-rays to create cross-sectional images
  • X-ray tube rotates 360 degrees around the patient
  • Measures transmitted radiation, generating a final image from multiple X-ray projections
  • Spiral CT images are acquired continuously in a helical pattern
  • High signal for bone, low signal for soft tissue
  • Better for visualizing bony structures than soft tissue
  • Faster than MRI, more readily available
  • Higher radiation dose than MRI
• MRI (Magnetic Resonance Imaging)
  • Uses a magnetic field and radio waves to create detailed images of organs and tissues
  • Atoms align with the magnetic field
  • Radio waves are sent to change atom positions
  • As atoms return to their original position they release signals
  • Signals are processed by a computer to produce an image
  • Can display high soft tissue details, multiple planes, and is radiation free.
  • Can be expensive and time consuming

Comparative Table

• Duration, cost, dimensions, soft tissue, bone, and radiation characteristics of CT, MRI, X-ray, and Ultrasound modalities.

Normal Ultrasound Anatomy

• Images of various anatomical structures and locations of the brain

Normal CT Anatomy

• Images showing different structures (e.g. bones) and their position
• Images illustrating specific brain structures and regions
• Also displays various structures, like sinuses.

Cranial Fossae

• Anterior, middle and posterior fossae. Each accommodates different brain structures and regions.

CSF Spaces

• CSF (cerebrospinal fluid) spaces, also known as extra-axial spaces contain fluid.

Brain Lobes

• The brain is divided into lobes.

Grey Matter Structures

• Structures visible on CT images (e.g., cortex, insula, basal ganglia, and thalamus)

Insula

• Location and significance

Basal Ganglia and Thalamus

• Importance of these brain structures in imaging

White Matter Structures

• Structures of white matter (internal capsules and corpus callosum) in CT images.

Internal Capsules

• Clinical significance of the internal capsule

Corpus Callosum

• Description in imaging

Anterior Commissure

• Description via imaging

Posterior Fossa

• Location and structures of the posterior fossa

Cerebellar Arterial Territories

• Cerebral arteries (anterior, middle, posterior)

Calcified Structures

• Important structures found in the brain, that will usually appear calcified in older adults

CT Angiographic Anatomy

• Different vascular structures (arteries, veins) appear different on CT

Head Trauma

• Appearance of blood on imaging (e.g., epidural, subdural, subarachnoid)

Effective Radiation Doses

• Radiation dose data for specific CT procedures and examinations

MRI

• Basic Physics of MRI
• Various types of MRI scans; T1, T2, etc. 
• Safety facts and advantages/disadvantages of MRI

Normal MRI Anatomy

• Illustrations of normal anatomy, with labeled structures.