Medical imaging
is vital in the detection and treatment of stroke
Medical imaging is a
vital part of the diagnosis and assessment of acute stroke and for determining the best
course of stroke treatment and rehabilitation. When a patient with suspected stroke enters
the hospital, the first step is to immediately determine which type of stroke has occurred
and to rule out bleeding (hemorrhage) of the brain. Computed
Tomography (CT) is the primary imaging examination used to differentiate between
bleeding (hemorrhage) and ischemia in patients with suspected stroke. It is critical to
determine if bleeding is present prior to administering TPA, since the blood thinning
effects of the TPA can make the bleeding worse. Even if the stroke is ischemic (caused by
a clot), if the stroke is more than three hours old, administration of TPA might worsen
the condition by causing bleeding in the brain.
 |
Colored CT image of the brain,
purple area on right of image indicates stroke |
CT imaging is also
useful to determine if a person's stroke symptoms are being caused by disease other than
stroke, such as a brain tumor or subdural hematoma (bleeding usually caused by head
trauma). CT imaging also helps doctors determine a stroke's size, location and cause, and
shows the extent of damage to the brain. New methods of CT imaging are being developed to
help doctors more quickly determine the "age" of the stroke and type of stroke
which is present and to decide which course of treatment is necessary. Sometimes there are
multiple strokes present in the brain, or a combination of new strokes that have just
occurred and older strokes which may have happened earlier (from a few days to a few years
earlier).
 |
The technologist prepares a
patient for a CT scan |
Magnetic
resonance (MR) imaging is also used increasingly in the diagnosis and treatment of
stroke. New types of so called "diffusion MR imaging" can show a stroke much
earlier than conventional MR imaging, allowing doctors to begin treatment sooner. Medical
research shows that when a stroke happens, brain cells in the area of the stroke set off a
sort of chain reaction that can lead to secondary brain cell injury. This secondary injury
can damage or even kill brain cells in a much larger surrounding area. Diffusion MR
imaging is being used to assist doctors in the development of "brain saving"
neuroprotective agents which disrupt the process that kills previously healthy brain cells
in the area surrounding the stroke.
 |
EPI-MR image of the brain, acquired
in less than a second. Bright "dot" (circled in yello) shows a stroke which
occured 4 hours earlier. |
Image
Guided Therapy of Stroke
Another innovation in
stroke treatment under development is the drug pro-urokinase. When using pro-urokinase to
treat acute ischemic (clot) stroke, an interventional neuro-radiologist delivers the drug
directly to the clot using a catheter whereas treatment with TPA is done via injection
into the bloodstream (for example via an arm vessel). Using x-ray
angiography for guidance, the doctor maneuvers the catheter (thin flexible tube) into
the vicinity of the stroke and administers the pro-urokinase directly to the clot. This
new method of "therapeutic imaging" with pro-urokinase allows a longer window
for delivery of the clot-buster drug, about twice the time window as for TPA, which is
only three hours.
Stroke
Victims Should Seek Immediate Attention at an Acute Care Hospital
While medical imaging
of stroke and vascular disease that can cause stroke may be performed at both inpatient
and outpatient imaging centers, treatment of stroke requires acute inpatient care. If a
person believes he or she is having a stroke, he or she should be taken immediately to an
emergency room or should call 911 for an ambulance.
Updated: January 14, 2008
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