CT scans

Computerised tomography (CTA scan that generates a series of cross-sectional X-ray images.) scanning is an X-rayA type of electromagnetic radiation used to produce images of the body. technique that produces a three-dimensional view of the body. CTA scan that generates a series of cross-sectional X-ray images. scanning is valuable in ruling out other conditions that can mimic a stroke, and in detecting a haemorrhageThe internal or external loss of blood from a blood vessel. - although even if the CTA scan that generates a series of cross-sectional X-ray images. scan is normal, an ischaemic stroke may still be present.[1] Despite this, CTA scan that generates a series of cross-sectional X-ray images. is often the first recommended imaging study of the brain when a stroke is suspected.[3]

CTA scan that generates a series of cross-sectional X-ray images. scans are very accurate in showing up a haemorrhageThe internal or external loss of blood from a blood vessel. within the first 12 hours, although their ability to pick up this condition lessens over time, as the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. is cleared by the body

CTA scan that generates a series of cross-sectional X-ray images. angiographyX-ray imaging of the blood vessels following the injection of a dye to improve visibility. is a type of CTA scan that generates a series of cross-sectional X-ray images. scanning used to produce detailed images of the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels; it is reliable in picking up any narrowing, or stenosisNarrowing of a tubular structure or valve., of the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels, the presence of any clots, and aneurysms. CTA scan that generates a series of cross-sectional X-ray images. angiographyX-ray imaging of the blood vessels following the injection of a dye to improve visibility. can also be used to show which parts of the brain have a better bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. supply than others.[2]

Another technique, perfusion CTA type of CT (computed tomography) scan, during which contrast medium is injected to enhance the visibility of structures., uses a contrast agentA substance taken (either by mouth or into a vein) by a person who is about to undergo an imaging investigation, to improve the visibility of the structures being imaged. Also known as contrast medium. to assess bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. supply. It can be employed to estimate the volume of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. supplying the brain (cerebral bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. volume), and the cerebral bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. flow. In this way, perfusion CTA type of CT (computed tomography) scan, during which contrast medium is injected to enhance the visibility of structures. can highlight the areas of the brain with reduced bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. flow.[2]

CTA scan that generates a series of cross-sectional X-ray images. scans are considered by some doctors to be the best imaging test for detecting subarachnoid haemorrhageBleeding into the subarachnoid space surrounding the brain, the area between two of the three layers (meninges) surrounding the brain and spinal cord (the arachnoid mater and the pia mater). , although recent studies suggest magnetic resonance imagingA technique for imaging the body that uses electromagnetic waves and a strong magnetic field. (MRIAn abbreviation for magnetic resonance imaging, a technique for imaging the body that uses electromagnetic waves and a strong magnetic field.; see below) may be just as effective.[1,4] CTA scan that generates a series of cross-sectional X-ray images. scans are very accurate in showing up a haemorrhageThe internal or external loss of blood from a blood vessel. within the first 12 hours, although their ability to pick up this condition lessens over time, as the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. is cleared by the body. (This is not the case for ischaemic stroke, where scanning actually becomes more sensitive over time.)[1]

References: 
  1. Yew KS and Cheng E. Acute stroke diagnosisThe process of determining which condition a patient may have.. Am Fam Physician. 2009; 80: 33-40.
  2. Schellinger PD, Fiebach JB, Hacke W et al. Imaging-based decision making in thrombolytic therapy for ischemic stroke: present status. Stroke 2003;34:575-83.
  3. Khaja AM and Grotta JC. Established treatments for acuteHas a sudden onset. ischaemic stroke. Lancet 2007; 369: 319-30.
  4. Sahni R and Weinberger J. Management of intracerebralWithin the brain. hemorrhage. Vasc Health Risk Manag 2007; 3: 701-9.