Stroke, whether ischemic (due to blockage in brain’s blood supply) or hemorrhagic (due to bleeding in the brain), can result in long-lasting complications if not attended immediately. Early diagnosis of a stroke — including what type it is — can significantly reduce the patient’s chances of living with a disability.
Stroke is suspected clinically and can be confirmed with clinical examination and brain imaging techniques. They also help to find out the cause, part of the brain affected and bleeding in the brain. Finally these tests play in planning the treatment and possible outcomes.
The article talks about various imaging techniques used to confirm the presence of stroke.
Brain Imaging Techniques
The first-line tests to assess brain function and its blood supply include:
- Magnetic resonance imaging (MRI): This test provides cross-sectional images of the brain. It helps in diagnosing a stroke and regions of the brain affected by the stroke. MRI is very sensitive and specific in differentiating ischemic lesions and identifying other conditions that may resemble a stroke.. MRI can uncover any brain damage within 20 minutes of beginning of stroke symptoms.
- Computerized tomography (CT): it is more widely available in our country. It can very easily diagnose the hemorrhagic type of stroke. In ischemic stroke it may be normal for few hours however it can show us early signs of stroke or impending brain damage. It is more popular to diagnose stroke as it is easy to do, takes less time and is easily available.
Advanced Stroke and Neurovascular Imaging
In addition to the above first-line imaging techniques, the mentioned tests are advanced tools that provide additional and critical information about the complexity and location of the stroke.
- CT angiography: This involves a CT scan along with a dye injected to obtain pictures of blood vessels in the brain. CT angiogram also helps locate blocked or narrow blood vessels, aneurysms, or other abnormal blood vessel formations.
- CT perfusion: It is a type of CT test used as an adjunct with CT angiography to diagnose stroke. It aids in differentiating ischemic brain areas (penumbra) from the irrevocably damaged brain area (infarct core). Broadly speaking when patients of stroke come late to the hospital, this test can tell us whether giving treatment is going to be beneficial to the patient or not.
- Magnetic resonance angiography (MRA): This type of test involves MRI to create two- or three-dimensional images of the structure of your blood vessels supplying the head and neck. This test does not involve any injection of the dye so is more useful in patients who have poor kidney function or history of drug allergy.
- Digital Subtraction Angiography (DSA) / Catheter angiography: this is the gold standard test to detect problems of blood vessels of the brain. This test offers high-resolution images of the blood vessels of the brain, spine or head and neck. Catheter angiography is a minimally invasive technique where a small catheter is introduced in the artery supplying the brain. A dye is injected, and images are taken that show your blood vessels’ structure and the blood flow.
- Transcranial Doppler (TCD): It is an ultrasound technique that allows your doctor to check the blood circulation within your brain. It is especially useful to detect delayed complications like vasospasm which can occur in hemorrhagic stroke patients