CT of the Head

Computed tomography, also known as a CT scan, is a noninvasive, painless process used to produce rapid, clear two-dimensional images of organs, bones, and tissues. Neurological CT scans are used to view the brain and spine. These scans can detect bone and vascular irregularities, certain brain tumors and cysts, herniated discs, epilepsy, encephalitis, spinal stenosis (narrowing of the spinal canal), a blood clot or intracranial bleeding in patients with stroke, brain damage from head injury, and other disorders.

Noncontrast CT is used to rule out intracranial hemorrhage, tumor or infection. MR diffusion-weighted imaging (DWI) demonstrates acute infarction, and a Gradient-Recalled Echo (GRE) sequence excludes intracerebral hemorrhage. CT angiography (CTA) and MR angiography (MRA) are used to evaluate intra- and extracranialintravenous thrombolytics, or intra-arterial or mechanical thrombolysis.

Perfusion imaging using CT requires either a diffusible inert gas indicator such as xenon (Xe) or a non-diffusible indicator such as an iodinated contrast agent. The CT scanner is then used to capture images as the agent passes through the cerebral circulation and accumulates in the cerebral tissues. Potential advantages of CT perfusion imaging are that it is less invasive than CT angiography and more widely available than MR imaging. However, CPT is still considered experimental at this time as there have not been sufficient studies to demonstrate that the benefit of the technique outweighs the risks assosicated with the potential for over exposure to x-rays. Some carriers are covering this procedure for acute stroke with consideration of thrombolytic agents.