Imaging modalities

• Radiography plays a minor role in evaluating neurologically ill or injured patients.
• Computed tomography (CT) uses ionizing radiation to create anatomic images.

Computed tomography

• CT is widely available and allows for rapid imaging with high resolution.
• CT contrast imaging can be used to assess blood-brain barrier disruption and cerebral vasculature.

Magnetic resonance imaging

• MRI is more sensitive than CT for detecting brain and spine pathology.
• MRI uses a strong magnetic field and radiofrequency pulses to create images.

Nuclear medicine

• Nuclear medicine studies are used for brain perfusion, leak localization, and infection monitoring.
• Positron emission tomography (PET) and single-photon emission tomography (SPECT) are used in epilepsy evaluation.

Brain patterns of disease

• Cerebral edema is classified as cytotoxic, vasogenic, or interstitial edema.
• Cytotoxic edema is caused by ischemia, while vasogenic edema is caused by blood-brain barrier disruption.

Cytotoxic edema

• Cytotoxic edema appears as areas of hypodensity on CT and increased intensity on T2-weighted and FLAIR MRI sequences.
• Gyri become swollen, and sulci are effaced in cytotoxic edema.

Vasogenic edema

• Vasogenic edema involves white matter with relative sparing of gray matter.