Images for The Diagnosis of Acute Stroke
November 22nd, 2011 | 
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Health professionals also use various diagnostic imaging technique for evaluating patients with symptoms of stroke. The imaging procedure most widely used is the computed tomography (CT). Also known as CAT scan or CT scan, it creates a series of cross-sectional images of the head and brain. Because it is immediately available at all times in most major hospitals and produces images quickly, CT is the preferred technique for the diagnosis of acute stroke.
Computed tomography also has unique diagnostic benefits. Quickly dismisses bleeding may occasionally show a tumor that may present symptoms similar to a stroke or may even show evidence of early infarction. Heart attacks usually occur in a CT scan about 6 to 8 hours after onset of stroke symptoms.
If the stroke is caused by hemorrhage, a CT scan may show evidence of bleeding in the brain almost immediately after onset of symptoms of stroke.Bleeding is the main reason for avoiding certain treatments with drugs such as thrombolytic therapy, the only proven treatment for stroke. Thrombolytic therapy can not be used until the doctor can confidently diagnose the patient has an ischemic stroke because this treatment may increase bleeding and could worsen a hemorrhagic stroke.
Another diagnostic imaging technique used in patients with symptoms of stroke is the exploration of magnetic resonance imaging (MRI English). The study of magnetic resonance imaging uses magnetic fields to detect subtle changes in brain tissue content. One effect of stroke is an increase in water content in brain tissue cells, a condition called cytotoxic edema. The MRI can detect edema a few hours after stroke onset. The benefit of the study using magnetic resonance imaging compared to CT scans is that MRI can detect small infarcts better immediately after stroke onset.
Unfortunately, not all hospitals have access to diagnostic equipment and magnetic resonance imaging procedure is time consuming and expensive. Neither this study is accurate in determining if the patient is suffering a hemorrhage. Finally, because the study of magnetic resonance imaging takes longer to perform than CT should not be used if you delay treatment.
Other types of scans MRI, often used to diagnose stroke and predict the risk of stroke, are magnetic resonance angiography (MRA) and functional magnetic resonance imaging (fMRI). Neurosurgeons use MRA to detect stenosis or blockage of the arteries of the brain inside the skull by mapping flowing blood to the brain. The study of functional magnetic resonance imaging uses a magnet to pick up signals from oxygenated blood can show brain activity through increases in local blood flow. Duplex Doppler ultrasound and arteriography are two diagnostic imaging techniques used to decide whether a person would benefit from a surgical procedure called carotid endarterectomy. This surgery is used to remove fatty deposits from the carotid arteries and can help prevent stroke.
Doppler ultrasound is a noninvasive test, which causes pain in the neck sent sound waves above the range that the human ear can hear. The echoes bounce off the moving blood and tissue in the artery and can be converted into an image. Ultrasound is quick, painless, risk-free and relatively inexpensive compared with magnetic resonance angiography and arteriography. But ultrasound is not considered as accurate as arteriography. Arteriography is an X-ray of the carotid artery taken when injected into the artery a special dye. The procedure carries its own small risk of causing a stroke and is expensive to perform. The benefits of angiography in comparison to magnetic resonance imaging techniques and ultrasound are that it is very reliable and still is the best way of measuring carotid artery stenosis. Even so, significant advances are being made every day related to non-invasive imaging techniques such as functional magnetic resonance imaging.
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