Brain scans are non-invasive tools that visualize the brain’s internal structures and processes. These technologies help medical professionals understand brain structure, function, and activity. Each scan offers unique insights, providing information for diagnosing and monitoring neurological conditions.
Computed Tomography (CT) Scans
Computed Tomography (CT) scans use X-rays to generate cross-sectional images of the brain. They are effective at showing dense structures like bones, making them valuable for detecting skull fractures. CT scans can also quickly identify hemorrhage within the brain, and large structural abnormalities such as tumors or fluid collections.
The speed of CT scans makes them useful in emergency situations. For head injuries or suspected strokes, CT provides rapid assessment for bleeding or fractures. Sometimes, a contrast agent is administered to enhance the visibility of specific tissues or blood vessels.
Magnetic Resonance Imaging (MRI) Scans
Magnetic Resonance Imaging (MRI) uses strong magnetic fields and radio waves to create detailed images of the brain’s soft tissues. This method does not involve ionizing radiation, unlike CT scans. MRI provides superior soft tissue contrast, allowing clearer visualization of white and gray matter, which helps identify subtle abnormalities.
MRI scans can reveal a wide range of conditions, including tumors, inflammation (such as from multiple sclerosis), and the effects of strokes or infections. They also detect fluid leaks or issues within blood vessels. The detailed images produced by MRI are valuable for diagnosing and monitoring many neurological disorders.
Functional Magnetic Resonance Imaging (fMRI) Scans
Functional Magnetic Resonance Imaging (fMRI) is a specialized MRI that focuses on brain activity, not just structure. This technique measures changes in blood flow and oxygenation, known as the blood-oxygen-level dependent (BOLD) signal, which links to neuronal activity. When a brain area becomes more active, blood flow to that region increases to meet heightened oxygen demand.
fMRI scans show which brain areas become active when a person performs tasks like speaking, moving, or thinking. This capability is utilized in research to understand brain function and in pre-surgical planning to map critical brain regions. The technology helps identify functional areas to avoid during neurosurgery, preserving cognitive abilities.
Positron Emission Tomography (PET) Scans
Positron Emission Tomography (PET) scans involve injecting a small amount of a radioactive tracer, often a glucose analog, into the bloodstream. This tracer travels through the body, accumulating in organs and tissues based on their metabolic activity. The PET scanner then detects emissions from this substance, creating images that visualize metabolic processes and blood flow.
PET scans are useful for identifying areas of abnormally high or low metabolic activity. Such patterns can indicate tumors, as cancer cells often have increased glucose uptake. PET also helps diagnose neurodegenerative conditions like Alzheimer’s disease by showing reduced glucose metabolism or the presence of amyloid plaques. It assists in localizing seizure foci or detecting changes associated with Parkinson’s disease.
Electroencephalography (EEG)
Electroencephalography (EEG) measures the brain’s electrical activity through electrodes placed on the scalp. These electrodes detect electrical signals produced by brain cells, which are recorded as wave patterns. Unlike imaging scans, EEG directly assesses electrical signals rather than creating a visual image of brain structure or metabolism.
EEG is used to identify abnormal electrical discharges, characteristic of seizures and epilepsy. It also provides insights into sleep disorders by analyzing brainwave patterns. For brain injury cases, EEG helps reveal changes in normal brain activity. The procedure is safe and painless, offering a direct assessment of brain function.