A cranial CT scan is computed tomography of the head, including the skull, brain, orbits (eye sockets), and sinuses.

A head CT will produce an image from the upper neck to the top of the head. It is important that once your head is in place, you do not move it during the test; if you are unable to keep your head still, immobilization may be needed. All jewelry, glasses, dentures, and other metal should be removed from the head and neck to prevent obstruction of the images.

A contrast dye may be injected into a vein to further check a mass. The mass becomes brighter with contrast dye if it has a lot of blood vessels. Contrast dye is also used to produce an image of the blood vessels of the head and brain.

The total amount of time in the CT scanner is usually a few minutes.

Generally, there is no preparation necessary.

The contrast dye injection may cause a slight temporary burning sensation in the arm, metallic taste in the mouth, or whole body warmth. This is a normal occurrence and will disappear in a few seconds.

Otherwise, the CT scan is painless.

A CT scan is recommended to help:

• Evaluate acute cranial-facial trauma
• Diagnose an acute stroke
• Check for suspected subarachnoid or intracranial hemorrhage
• Check for causes of headaches
• Check for causes of loss of sensory or motor function
• Determine if there is an abnormal development of the head and neck

There may be signs of:

• Trauma
• Bleeding (for example, chronic subdural hematoma or intracranial hemorrhage)
• Stroke
• Masses or tumors
• Abnormal sinus drainage
• Sensorineural hearing loss
• Malformed bone or other tissues
• Brain abscess
• Cerebral atrophy (loss of brain tissue)
• Brain tissue swelling
• Hydrocephalus (fluid collecting in the skull)

• Acoustic neuroma
• Acoustic trauma
• Acromegaly
• Acute (subacute) subdural hematoma
• Amyotrophic lateral sclerosis
• Arteriovenous malformation (cerebral)
• Benign positional vertigo
• Throat cancer
• Central pontine myelinolysis
• Cerebral aneurysm
• Cushing's syndrome
• Deep intracerebral hemorrhage
• Delirium
• Dementia
• Dementia due to metabolic causes
• Drug-induced tremor
• Encephalitis
• Epilepsy
• Essential tremor
• Extradural hemorrhage
• Familial tremor
• General paresis
• Generalized tonic-clonic seizure
• Hemorrhagic stroke
• Hepatic encephalopathy
• Huntington's disease
• Hypertensive intracerebral hemorrhage
• Hypopituitarism
• Intracerebral hemorrhage
• Juvenile angiofibroma
• Labyrinthitis
• Lobar intracerebral hemorrhage
• Ludwig's angina
• Mastoiditis
• Melanoma of the eye
• Meniere's disease
• Meningitis
• Metastatic brain tumor
• Multi-infarct dementia
• Multiple endocrine neoplasia (MEN) I
• Neurosyphilis
• Normal pressure hydrocephalus (NPH)
• Occupational hearing loss
• Optic glioma
• Orbital cellulitis
• Otitis media; chronic
• Otosclerosis
• Partial (focal) seizure
• Partial complex seizure
• Petit mal seizure
• Pituitary tumor
• Primary brain tumor
• Primary lymphoma of the brain
• Prolactinoma
• Retinoblastoma
• Reye's syndrome
• Schizophrenia
• Senile dementia/Alzheimer's type
• Acute sinusitis
• Stroke secondary to atherosclerosis
• Stroke secondary to cardiogenic embolism
• Stroke secondary to FMD
• Stroke secondary to syphilis
• Subarachnoid hemorrhage
• Syphilitic aseptic meningitis
• Temporal lobe seizure
• Toxoplasmosis
• Transient ischemic attack (TIA)
• Wilson's disease

Iodine is the usual contrast dye. Some patients are allergic to iodine and may experience a reaction that may include hives, itching, nausea, breathing difficulty, or other symptoms.

As with any x-ray examination, radiation is potentially harmful. Consult your health care provider about the risks if multiple CT scans are needed over a period of time.

A CT scan can decrease or eliminate the need for invasive procedures to diagnose problems in the skull. This is one of the safest means of studying the head and neck.