A stroke is an event where a blood vessel serving the brain is either blocked by a clot or ruptures. In either case, brain cells, deprived of oxygen and nutrients, can die, and this can result in brain damage, disability, or death. When brain cells die, the part of the body that the affected parts of the brain control is affected with, for example, paralysis, loss of language skills, loss of motor skills, or loss of vision. Stroke is a leading cause of death in the United States, and every 45 seconds someone in the US has a stroke. Every three minutes, someone in the US dies from a stroke.
There are two main types of strokes, hemorrhagic and ischemic. Hemorrhagic strokes are caused by the rupture of a blood vessel, which causes bleeding. Ischemic strokes are caused by blood clots blocking a vessel that feeds the brain. Most strokes are ischemic strokes.
When stroke is suspected, time is critical and every minute counts. In the time immediately following an ischemic stroke, if blocked blood vessels can be opened by removal or dissolving of the blood clot, chances for recovery are significantly improved. Neuroradiology, or medical imaging of the brain, is essential to prompt diagnosis of stroke.
Neuroradiology for Stroke Diagnosis and Classification
Neuroradiology images are critical in the evaluation of patients who are believed to be suffering from stroke, because they can confirm the diagnosis and assist with prompt initiation of treatment. Besides determining whether a patient’s symptoms are caused by stroke, another primary goal of neuroradiology in patients with stroke symptoms is distinguishing between hemorrhagic and ischemic stroke, because treatment options differ based on the type of stroke. Computed tomography (CT), magnetic resonance imaging (MRI), and angiography are three types of neuroradiology studies that are performed when stroke is suspected.
CT is often the first diagnostic test performed by emergency room doctors. CT imaging uses computers and x-ray images to generate detailed pictures of the brain. CT can confirm whether someone is having a stroke, and whether it is caused by hemorrhaging in the brain.
MRI uses magnetic fields rather than ionizing radiation to produce detailed images of the brain. It can identify and localize the site of a stroke and the source. In some cases, MRI can identify areas of the brain that are deprived of blood flow in order to guide stroke treatment.
Angiography uses x-rays along with a contrast dye that is injected into veins to highlight blood vessels. Neuroradiology specialists can use angiography to find the exact location of bleeding or blockage in the brain. It can also be used to guide catheters to affected areas of the brain in order to administer treatment.
Neuroradiology and Treatment of Stroke
Neuroradiology is not just critical to the diagnosis of stroke, it is also increasingly used in treatment of stroke. Drugs called tissue plasminogen activators (tPA), also known as “clot busters” were introduced in the 1990s, and for a long time were the only treatment for ischemic strokes. It is given either systemically, with an IV, or it can be delivered directly to the site of a clot, guided by neuroradiology images. Timing of tPA is critical, however. It must be given with a certain time period after a stroke, or risks of excess bleeding increase. Moreover, tPA doesn’t always work, particularly on large clots.
Today, however, neuroradiology procedures allow doctors, guided by neurological imaging, to physically enter blood vessels where clots are located and remove the clots. The first devices used for this procedure were tiny corkscrew devices that were originally designed to remove foreign objects left behind after vascular surgery. The corkscrew could also be threaded through an artery using a catheter, grab onto a clot, and then be threaded back out, removing the clot.
Newer clot removing devices have since been invented. The ones used today are expandable cage-like devices that are inserted into clots and expanded. Clots stick to the cage material, allowing doctors to thread the clot out with a catheter. There are also vacuum devices that can suction out clots. The main issue facing doctors with access to these techniques has to do with identifying patients who can benefit most from them, because clot removal isn’t without risk.
American Society of Neuroradiology Imaging Recommendations for Stroke Patients
Many neuroradiology techniques are available to physicians for evaluating patients who may be having a stroke, but knowing which ones to use, how to use them, and in what order to use them can be a challenge. Time, cost, and available expertise are all factors influencing the choice of neuroradiology technique in these situations. The American Society of Neuroradiology along with the American College of Radiology and the Society of NeuroInterventional Surgery published guidelines in the American Journal of Neuroradiology in 2013 to help physicians make the best choices within their particular limitations.
A three-step algorithm was created that involves determining whether an intracranial hemorrhage is present, whether the patient is a candidate for tPA, and whether endovascular therapy is available and appropriate for the patient. At each of the three steps, neuroradiology procedures are suggested, including non-contrast CT imaging, CT angiography, duplex ultrasound, and MRI, and explanations are provided about how these neuroradiology techniques assist with diagnosis and treatment planning.
Stroke is a leading cause of death and disability, and neuroradiology techniques can be used not only to diagnose stroke (as well as determining the type of stroke), but also in treatment of stroke, whether through delivery of tPA to the site of a clot, or the use of physical devices that remove a clot through a blood vessel. Knowing which neuroradiology technique is appropriate isn’t always clear, but the American Society of Neuroradiology has developed imaging recommendations that physicians can use based on their facility’s available equipment, time restraints, and expertise.
SteleRAD is a South Florida practice group owned and operated by board-certified radiologists with over 40 years of experience in a broad range of radiology specialties, including neuroradiology. Dr. Carl Raboi, Dr. Shawn Fibkins, Dr. Robert Baker, Dr. Richard Spira, and Dr. Michael Digiorgio are SteleRAD physicians with expertise and experience in the subspecialty of neuroradiology, who deliver timely and accurate interpretations for hospitals, imaging centers, and physician groups. To learn more about SteleRAD‘s neuroradiology services, contact SteleRAD online or call 954-358-5250.