A computed tomography (CT) scan of the brain is a rapid, noninvasive imaging technique that uses x-rays passed through the brain from multiple directions to create cross-sectional images based on tissue density differences.
A noninvasive imaging test that uses X-rays to create detailed cross-sectional (axial) images of the brain, skull, and surrounding structures.
The degree of x-ray attenuation as radiation passes through tissue is measured , and computers integrate this information to construct high-resolution (~1 mm) images of brain structures.
CT of the brain scanning provides excellent visualization of acute hemorrhage, calcifications, skull fractures, hydrocephalus, space-occupying lesions such as tumors, hematomas and stroke.
It can differentiate structures that differ only slightly in density and provides direct visualization of the ventricular system.
Intravenous iodinated contrast material can be administered to enhance imaging of bleeding, neoplasms, infection, and inflammation by exploiting disruption of the blood-brain barrier.
It has widespread availability, rapid acquisition time making it the preferred modality for acute trauma, rapidly evolving neurologic disorders, and patients requiring constant monitoring or those who cannot undergo MRI due to pacemakers, metallic implants, or severe claustrophobia).
CT of brain main disadvantages are ionizing radiation exposure of approximately 1.3-2 mSv per scan and lower sensitivity compared to MRI for many neurologic conditions, particularly posterior fossa lesions, acute infarction, and certain tumors.
Doctors commonly perform brain CT scans to evaluate: • Head injuries (trauma) • Strokes • Bleeding (hemorrhage) • Tumors • Infections • Hydrocephalus
Generally preferred over MRI imaging for the evaluation of acute subarachnoid hemorrhage, acute head trauma, and bone abnormalities.
With shielding the uterus is exposed to less than 1 mrad during pregnancy.
Un-enhanced study is indicated in patients with suspected stroke and can distinguish acute intracerebral hemorrhage from ischemia.
Unenhanced CT of the brain nearly 100% sensitive for intracranial hemorrhage and approximtely 90% for subarachnoid hemorrhage.