Imaging Studies for Stroke


A stroke is an urgent medical condition that can have serious life-altering consequences for stroke survivors. While most of the time neurologists can diagnose a stroke by obtaining a clinical history and performing a thorough neurological physical examination, modern diagnostic imaging techniques can help confirm the diagnosis, can distinguish between the different types of stroke and can also determine whether there have been silent strokes in the past.

 These tests can also be used to identify medical conditions that produce symptoms similar to those of a stroke. There are several types of commonly used diagnostic imaging tests that are obtained to help medically evaluate a patient who may be experiencing a stroke.

Imaging Studies

Imaging studies include different types of pictures and photographic images that evaluate the inside of the body. The various types of imaging studies used for stroke employ diverse techniques to distinguish the shapes, density, shadows, fluid movements and metabolic activity within the brain. Imaging techniques that are used in stroke assessment are specifically calibrated to view the changes in the brain that occur during a stroke.

  • Magnetic Resonance Imaging/MRI - a large machine measures the magnetic activity of the different areas of the brain to create a picture. The picture shows differences in brain tissue that has undergone damage from ischemia. MRI imaging can detect strokes at a very early stage. Some patients who are prone to claustrophobia cannot tolerate MRI studies because the machine is enclosed and the study takes longer to complete than a CT scan.
  • MRI with Contrast - a dye can be injected into a vein prior to an MRI to better detect abnormal structures, such as tumors. MRI with contrast provides great detail, but some patients are unable to tolerate the contrast material due to sensitivity/allergies.
  • Magnetic Resonance Angiogram/MRA - an MRI with specific focus on the blood vessels in and around the brain. This type of study is used to detect blood clots, blood vessel defects such as aneurysms and arteriovenous malformations, and blood vessel disease.
  • Computerized Tomography/CT scan/CAT scan - a computerized product of many x-ray produced views results in a 3 dimensional picture of the brain.  CT scan is useful to evaluate for bleeding in the brain, yet often cannot detect very early ischemic strokes. CT scan can detect most strokes after 12 hours, but occasionally does not fully visualize strokes or other abnormalities in the brainstem.
  • CT with Contrast - a CT scan with the use of dye to help clarify the details of the pictures. As with MRI contrast, some patients cannot tolerate the dye.
  • CT Angiogram/CTA - a CT study used to visualize the blood vessels in the brain. Most hospitals have a standard procedure and preference for CTA or MRA depending on their equipment and skills. Either test can be used, and neither is uniformly considered to be superior to the other.
  • Positron Emission Tomography/PET - a radioactive particle is injected into the body and it's interaction with the body can be measured to detect abnormal levels of metabolic activity in the human body. PET scanning is relatively new and most medical facilities do not routinely use PET scan. It appears to show more promise in conditions characterized by metabolic tissue abnormalities, such as cancer, epilepsy and Alzheimer’s disease, than in stroke, which is characterized by damage and lack of activity of ischemic to brain tissue.
  • Single-Photon Emission Computer Tomography/ SPECT - an image using gamma radiation measures metabolic activity or blood flow in a given area of the body. SPECT scanning is more often used in stroke research than in stroke care.
  • Ultrasound - a technique that uses sound waves to detect the flow of fluid and density of masses in the body. This can be used to evaluate blood flow in the carotid arteries to determine whether there is a blood vessel abnormality or blood flow impairment that may increase the risk of a stroke.

A number of different types of imaging studies are used to confirm a stroke and often to help determine a treatment plan and to follow the progression. Sometimes, imaging studies are planned in advance, and sometimes they may be performed as an emergency. Imaging techniques for stroke are advanced and rapidly advancing to optimize the diagnostic information and help the stroke teams effectively care for stroke patients.

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