The Comprehensive Stroke Center at University Hospital
At the hospital, medical personnel will use one of more of the following diagnostic tests to determine the type of stroke and its location.
Tests That View the Brain
Computed Axial Tomography (CT scan, CAT scan): CT is a non-invasive, painless test that uses x-rays to produce a three-dimensional image of the interior of the patient’s head. An initial CT scan can quickly rule out hemorrhage or a brain tumor causing stroke-like symptoms. It may even show areas of the brain that are in danger of dying but still salvageable.
|CT scan of a patient who has had a left middle cerebral artery stroke. The arrow indicates the location of the stroke.|
Magnetic Resonance Imaging (MRI scan, MR scan): This is a non-invasive, painless test that uses magnetic fields to produce a three-dimensional image of the interior of the patient’s head. An MRI scan shows the brain and spinal cord in more detail than a CT scan does. MRI can be used to diagnose ischemic stroke, hemorrhagic stroke, and other problems involving the brain, brainstem, and spinal cord.
|MRI of a patient who has had a stroke of the left hemisphere of the brain. The arrow indicates the area that was affected.|
Tests that View the Blood Vessels Supplying the Brain
Carotid Ultrasound (Carotid duplex, Carotid doppler): This non-invasive test uses ultrasound waves – painless high-frequency radio waves – to take a picture of the carotid arteries in the patient’s neck and show the blood flow to the brain. It can show if the patient’s carotid artery is narrowed or blocked by atherosclerosis (hardened plaque buildup on the vessel wall).
|Left shows carotid doppler image of a normal carotid artery. Right shows a stenosis at the origin of the carotid artery.|
Cerebral Angiography: (Cerebral arteriogram, Digital subtraction angiography [DSA]): This is a minimally invasive test in which a thin, flexible catheter is inserted into an artery, usually in the patient’s groin, and steered through the blood vessels toward the brain. A special dye, which can be seen on x-rays, is injected through the catheter into the blood vessels leading to the brain. X-ray images show any abnormalities of the blood vessels, including narrowing, blockage or malformations (such as aneurysms or arteriovenous malformations). Cerebral arteriogram is a more difficult test than carotid ultrasound, MRA or TCD, but the results are the most accurate. Since it is an invasive procedure, there is a small associated risk of causing a stroke; at University Hospital, for academic years 2013-2014, 2014-2015 the stroke complication rate for diagnostic cerebral angiography is less than 1%.
|An angiogram showing one of the major blood vessels of the brain that is blocked causing a stroke (arrow indicates the location of the blockage).|
Angiography: (CT-angiography, CT-A,
CT-A is a recent development in diagnostic imaging for stroke that is poised to replace traditional cerebral angiography. It is much less invasive, as it does not require arterial catheterization, and results are available in about half the time. It can also catch aneurysms that cerebral angiography may miss. CT-A combines a regular CT scan with a contrast dye injected directly into a vein. The dye travels to the brain arteries, and images are created using a CT scan. These images show exactly how blood flows into the brain arteries.
|An example of a CT angiogram of the circulation of the brain.|
Magnetic Resonance Angiography (MRA): This is a special type of MRI scan used to see the blood vessels in the neck or brain. It can help determine the extent of damage.
|MRA of a patient showing the carotid artery circulation.|
Transcranial Doppler:(TCD) : TCD uses ultrasound waves to measure blood flow in some of the arteries in the brain.
Top shows a TCD of a normal artery. Bottom shows a severely stenosed internal carotid artery.
Though not routine, certain blood tests may used for specific stroke situations or when the cause of stroke is unclear (for example, in a young person without known stroke risk factors). Abnormal results may suggest a cause for the stroke. For example, a toxicology screen would show the presence of cocaine, which is a serious risk factor for stroke.