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Computed Tomography

Computed tomography (CT) is a computerized radiographic study that provides information about bones, soft tissues, and blood vessels. Neurological computed tomography scans of the head, face, orbits (eye sockets), sinuses, and spine can be used to diagnose fractures, deformities, disease, or degenerative conditions.

A computed tomography scan can also be used to obtain generalized information about the brain, because it can be performed quickly, is well tolerated by patients, and is widely applicable to many types of patients. Computed tomography studies of the brain are often used to evaluate trauma, hemorrhage (bleeding), vertigo (dizziness), headaches, and changes in a patient's level of consciousness.

Computed tomography is painless and does not require sedation. Occasionally, a contrast agent (dye) is given intravenously to obtain additional information.

Three dimensional computed tomography of
a patient with stab wounds to the neck, arrow
indicates the vertebral artery disruption.

Three-Dimensional Computed Tomography

Three dimensional computed tomography (CT) provides detailed information about bones in a three-dimensional format. A three-dimensional computed tomography study takes longer than a regular computed tomography study because many more radiographic images are obtained in smaller sections and at many different angles. After the images are obtained, a computed tomography technologist uses imaging software to digitally remove images of soft tissue so that only images of bone remain. The images of bone are then reassembled so that the bones appear as a three-dimensional image.

Physicians use three-dimensional computed tomography scans to evaluate deformities caused by disease, birth defects, or trauma and to plan reconstructive surgery.

Computed tomography angiogram of a large basilar
tip aneursym.

Computed Tomography Angiography

Computed tomography (CT) angiography allows blood vessels in the head and neck to be imaged in a three-dimensional format. Computed tomography angiography can be used to evaluate blockages or narrowing of blood vessels, aneurysms, and other blood vessel abnormalities. Contrast (dye) is administered intravenously before the procedure, which takes 20 to 30 minutes. Computed tomography angiography is painless, does not require sedation, and is noninvasive. That is, no incision is needed and no catheter is inserted into the body.

Computed Tomography Image Guidance

Computed tomography (CT) image guidance is used during surgery to help surgeons plan the best surgical approach and to locate tumors precisely. Before surgery, patients undergo computed tomography with special markers placed on their head. The markers are used to register landmarks so that the computed tomography scans can be entered into a computer in the operating room. The surgeon uses an instrument called a "wand" to touch the surgical area. The wand sends information to the computer to identify the location and size of the tumor. Computed tomography image guidance is primarily used for tumors involving bones in the skull, face, and spine.

Xenon Computed Tomography

A xenon computed tomography (CT) study of the brain is performed while the patient breathes a carefully regulated flow of xenon (a colorless, odorless gas). An intravenous line is inserted during the test, and patients are monitored closely. The procedure is painless and does not require sedation.

Xenon computed tomography studies are performed to evaluate the efficiency of blood flow to brain tissues. This test can help to determine whether surgery is needed to address a blockage or restriction of blood flow in the carotid artery, which provides the main blood supply to the brain. Occasionally, xenon computed tomography studies are also used to determine brain death.