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What is a Head Scan?

Cathy Crenshaw Doheny
Cathy Crenshaw Doheny

The term head scan can either refer to a cranial computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan of the head. Both the CT scan and the MRI scan are non-invasive methods to make pictures of a patient's head, including the brain, skull, and other tissues. Each type of head scan is painless and provides the physician with important information to diagnose a variety of conditions.

A cranial CT scan uses x-rays to make special cross-sectional images from the upper portion of the neck to the top of the head. To perform this head scan, the patient must lie on a table that slides into the CT scanner. While the patient lies inside the scanner, the x-ray beam circulates around the body to help make individual images, called slices. Contrast dye may be injected into a vein to highlight blood vessels or look for a tumor. Cranial CT is used to help diagnose and monitor various conditions, including a brain tumor, brain infection, hydrocephalus, and bleeding in the brain.

An MRI head scan is non-invasive.
An MRI head scan is non-invasive.

A head MRI uses magnets and radio waves, instead of radiation, to create pictures of the inside of the head. A magnetic field created by the MRI scanner forces hydrogen atoms in the patient's body to assemble in a particular manner. When the scanner sends out radio waves, they bounce off of the hydrogen atoms and a computer records their response, which create images, also known as slices.

A CT scan is a common method of getting images of a head.
A CT scan is a common method of getting images of a head.

To perform this type of head scan, the patient will also need to lie on a table that slides into a scanner. Small receivers, called coils, are arranged around the head to help the transmission of the radio waves. An IV contrast dye can also be used during a MRI to make the images clearer. A head MRI may be used to help diagnose and monitor a variety of conditions, including brain tumors, brain infections, multiple sclerosis, and abnormal brain development.

CT scanners are available in most hospital emergency rooms.
CT scanners are available in most hospital emergency rooms.

A head scan is typically performed using computed tomography when time is a factor, as CT scans only take a few minutes to complete, whereas MRI scans can take up to an hour. CT scanners are also usually available in most hospitals' emergency rooms. Examples of cases when a head CT scan may be preferable include when the patient has beginning symptoms of a stroke, acute trauma of the face and head, or bleeding in the brain. A MRI head scan, however, may be preferred to help give information about areas of the brain that are difficult to see on a CT scan. A head scan using magnetic resonance imaging can also show blood vessels, blood flow, and fluid that surrounds the spinal cord and brain.

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    • An MRI head scan is non-invasive.
      By: Pavel Losevsky
      An MRI head scan is non-invasive.
    • A CT scan is a common method of getting images of a head.
      By: svedoliver
      A CT scan is a common method of getting images of a head.
    • CT scanners are available in most hospital emergency rooms.
      By: SeanPavonePhoto
      CT scanners are available in most hospital emergency rooms.
    • CT scans are preferable when a patient has symptoms of face and head trauma.
      By: Scott Griessel
      CT scans are preferable when a patient has symptoms of face and head trauma.
    • A radiologist can locate abnormalities such as cancer in brain tissue using an MRI.
      By: EPSTOCK
      A radiologist can locate abnormalities such as cancer in brain tissue using an MRI.
    • A cranial CT scan use x-rays to make cross-sectional images of the neck and head areas.
      By: Tyler Olson
      A cranial CT scan use x-rays to make cross-sectional images of the neck and head areas.