COMPUTED TOMOGRPAHY HEAD (CT SCAN) Riga

Computed tomography (CT) of the head or Computed Axial Tomography (CAT) scanning uses a series of x-rays of the head taken from many different directions. Typically used for quickly viewing brain injuries, CT scanning uses a computer program that performs a numerical integral calculation (the inverse Radon transform) on the measured x-ray series to estimate how much of an x-ray beam is absorbed in a small volume of the brain. Typically the information is presented as a series of cross sections of the brain.

In approximation, the denser a material is, the whiter a volume of it will appear on the scan, just as in the more familiar "flat" X-rays, where dense bone appears white. CT scans are primarily used for evaluating swelling from tissue damage in the brain, bleeding, and in assessment of ventricle size. Modern CT scanning can provide reasonably good images in a matter of minutes. A spiral CT scan of the head may be performed in 10–30 seconds, making it a good option for children and adults with difficulty holding still for longer periods.  

Indication

Computed tomography (CT) has become the diagnostic modality of choice for head trauma due to its accuracy, reliability, safety, and wide availability. The changes in microcirculation, impaired auto-regulation, cerebral edema, and axonal injury start as soon as head injury occurs and manifest as clinical, biochemical, and radiological changes. Proper therapeutic management of brain injury is based on correct diagnosis and appreciation of the temporal course of the disease process. CT scan detects and precisely localizes the intracranial hematomas, brain contusions, edema and foreign bodies. Because of the widespread availability of CT, there is reduction in arteriography, surgical intervention and skull radiography.

Even in emergency situations, when a head injury is minor as determined by a physician's evaluation and based on established guidelines, CT of the head should be avoided for adults and delayed pending clinical observation in the emergency department for children. Many people visit emergency departments for minor head injuries. CT scans of the head can confirm a diagnosis of skull fracture or brain bleeding, but even in the emergency room such things are uncommon and not minor injuries so CT of the head is usually not necessary. Clinical trials have shown the efficacy and safety of using CT of the head in emergency settings only when indicated, which would be at the indication of evidence-based guidelines following the physical examination and a review of the patient's history.

What is CT Scanning of the Head?

Computed tomography, more commonly known as a CT or CAT scan, is a diagnostic medical test that, like traditional x-rays, produces multiple images or pictures of the inside of the body.

The cross-sectional images generated during a CT scan can be reformatted in multiple planes, and can even generate three-dimensional images. These images can be viewed on a computer monitor, printed on film or transferred to a CD or DVD.

CT images of internal organs, bones, soft tissue and blood vessels typically provide greater detail than traditional x-rays, particularly of soft tissues and blood vessels.

CT scanning provides more detailed information on head injuries, brain tumors and other brain diseases than regular radiographs (x-rays).

CT scanning of the head is typically used to detect:

• bleeding, brain injury and skull fractures in patients with head injuries.
• bleeding caused by a ruptured or leaking aneurysm in a patient with a sudden severe headache.
• a blood clot or bleeding within the brain shortly after a patient exhibits symptoms of a stroke.
• a stroke, especially with a new technique called Perfusion CT.
• brain tumors.
• enlarged brain cavities (ventricles) in patients with hydrocephalus.
• diseases or malformations of the skull.

CT scanning is also performed to:

• evaluate the extent of bone and soft tissue damage in patients with facial trauma, and planning surgical reconstruction.
• diagnose diseases of the temporal bone on the side of the skull, which may be causing hearing problems.
• determine whether inflammation or other changes are present in the paranasal sinuses.
• plan radiation therapy for cancer of the brain or other tissues.
• guide the passage of a needle used to obtain a tissue sample (biopsy) from the brain.