When it comes to stroke screening, one of the most common questions we hear is about the difference between CT scans and MRI scans. Both are vital tools for diagnosing strokes. A CT scan is often the first imaging test performed as it quickly detects bleeding in the brain or signs of an ischemic stroke. An MRI scan provides detailed images, making it ideal for identifying smaller or earlier strokes. Both play a crucial role in ensuring accurate diagnosis and timely treatment, helping healthcare professioanls tailor the best care for each patient.
Introduction to Stroke FAQ
A stroke is a serious condition that can have long-term consequences if left untreated. Strokes are caused by an interruption of blood supply to the brain due to a blocked or bleeding vessel.
Regardless of the cause, Dr. Manish Taneja, our stroke specialist in Singapore recommends addressing stroke symptoms immediately and getting prompt treatment. Keep reading to find out more about stroke causes, diagnosis, common tests, and where to seek stroke treatment in Singapore.
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Common Questions About CT Scans vs MRI Scans for Stroke
What is the difference between a CT scan and an MRI scan for stroke?
Both CT scans and MRI scans are important imaging tools used to diagnose stroke, but they provide different information and may be used at different stages of care.
- CT scan (Computed Tomography): Usually the first imaging test performed in an emergency. It quickly detects bleeding in the brain and helps doctors determine whether a stroke is ischaemic or haemorrhagic.
- MRI scan (Magnetic Resonance Imaging): Provides highly detailed images of brain tissue and can detect smaller or very early strokes that may not be visible on an initial CT scan.
The most appropriate scan depends on your symptoms, how long they have been present and the clinical situation.
Why is a CT scan usually performed first during a suspected stroke?
When every minute matters, speed is critical.
A CT scan can usually be performed rapidly and helps doctors:
- Detect bleeding within the brain
- Rule out conditions that mimic stroke
- Decide whether emergency treatments may be appropriate
- Determine whether further imaging is needed
Rapid diagnosis helps ensure patients receive the most appropriate treatment as quickly as possible.
When is an MRI recommended after a stroke?
An MRI may be recommended when doctors need more detailed information about the brain or blood vessels.
It may be useful for:
- Confirming small or early ischaemic strokes
- Evaluating transient ischaemic attacks (TIAs)
- Assessing the extent of brain injury
- Investigating unexplained neurological symptoms
- Planning long-term treatment and follow-up
MRI may also be combined with magnetic resonance angiography (MRA) to evaluate the brain's blood vessels.
Can CT and MRI both detect brain aneurysms?
Standard CT and MRI scans mainly assess brain tissue.
To evaluate blood vessels and detect aneurysms, specialists may recommend:
- CT Angiography (CTA)
- Magnetic Resonance Angiography (MRA)
- Cerebral angiography (Digital Subtraction Angiography) when detailed assessment is required
The choice of imaging depends on the suspected condition and the information needed for diagnosis or treatment planning.
What happens after my stroke scan?
Your specialist will interpret the scan together with your symptoms, examination findings and medical history.
Depending on the results, the next steps may include:
- Emergency stroke treatment
- Additional vascular imaging
- Medication to reduce future stroke risk
- Investigation of the underlying cause
- Referral for rehabilitation
- Long-term follow-up with a stroke or neurovascular specialist
The imaging findings help guide an individualised treatment plan rather than determining treatment on their own.
1. How to Diagnose a Stroke
Timely and correct diagnosis is crucial. If your doctor suspects that you might be having or have had a stroke, they need to rule out other conditions that might explain your symptoms. Tests are usually ordered to determine if someone is having a stroke and establish the type.
Time is of the essence. If your doctor strongly suspects that you might be having a stroke, they might prioritize treatment to take advantage of the golden hour of stroke.
2. What are Tests for a Stroke and Why?
Diagnosis of a stroke can be done through a combination of tests. A physical exam is often used to evaluate symptoms and gauge the severity of the stroke. Your doctor will be checking certain parameters such as the ability to move your arms and legs, facial movements, sensation to touch, and ability to speak clearly, among others.
Imaging tests are also used to take images in and around your brain to help find the site of the stroke and determine the type. Other tests for a stroke include lumbar puncture and heart and blood tests
3. Can an MRI Show a Stroke?
Yes. An MRI is an imaging test that uses powerful scanner magnets and radiofrequency waves to determine if there are changes in brain tissue. Because of how powerful and sensitive the test is, an MRI can reveal brain damage within an hour, paving the way for fast stroke treatment in Singapore.
4. What are Ministrokes and Can They be Diagnosed with a CT Scan?
Ministrokes are often used to refer to Transient Ischemic Attacks (TIA). TIA is a temporary lack of blood flow to the brain due to blockage. Although ministrokes are temporary and do not often cause permanent brain damage or disability, they can put someone at a higher risk of developing a stroke.
It is important to seek medical attention immediately if you notice signs of a stroke even if they last a few minutes. As part of the stroke screening routine, your doctor will likely use a CT scan to check for brain bleeds or major blockages that may have caused acute stroke. However, it is not accurate as an MRI.
5. If I am Checking my Brain for Stroke, Should I get a CT or an MRI Scan?
CT scans are widely available in most hospitals and are often used as the first choice if your stroke doctor needs urgent imaging. They provide information about the type of stroke and can help your doctor rule out other causes of your symptoms. They are faster for initial diagnosis.
On the other hand, an MRI provides detailed imaging and is very effective in providing information about the type and location of the stroke. Your doctor will evaluate your specific situation to determine which test to order. Usually, an MRI is more sensitive than CT scan.
6. How is it Determined if a Stroke is Ischemic or Hemorrhagic?
A stroke can either be hemorrhagic or ischemic. Hemorrhagic strokes are less common and develop when a blood vessel leaks or ruptures and bleeds into the brain. Ischemic strokes are more common and occur when blood flow to the brain is restricted.
A good neurointervention specialist may order a combination of tests including physical and neurological examination, blood tests, and imaging tests such as CT scan and MRI to determine the kind of stroke you might be having, its location, and its cause.
7. What Can a CT scan do that an MRI Cannot, and is it Better?
CT and MRI scans are two of the most effective medical imaging tests for determining the presence, type, and location of stroke. Unlike an MRI, a CT scan can show significant changes in brain tissue and is more effective at identifying brain bleeds.
When comparing the two, an MRI is more accurate while a CT scan is faster and easily accessible. Doctors often get a CT scan first, then if needed, they may later order an MRI scan.
8. Why Would a Doctor Ask for a CT Instead of an MRI?
For better stroke management, your doctor may order a CT scan if they need faster results. In addition, some patients may be unable to go inside an MRI machine due to several reasons such as metal implants (e.g. pacemakers and metal screws) that cannot be removed. Be sure to ask your doctor why they ordered one test over the other.
9. Why Haven't MRIs Completely Replaced CT Scans?
Although MRIs are more detailed and have higher clarity, they have a few drawbacks. MRI tests take much longer than CT scans and may not be appropriate in emergency situations.
Patients with claustrophobia and those who may not be able to hold still for the duration of the MRI scan are better diagnosed using a CT scan. There is also the issue of limited availability, but you can still get expert stroke care and MRI scans at a specialised stroke clinic in Singapore.
10. What is the Best Time of Day to get an MRI or CT Scan Done?
Although there is no specific best time of day to get either test done, there is a growing recognition of factors that may impact MRI measures. One such factor is the time-of-day (TOD) effect, a factor that could impact brain volume.
More research still needs to be done on whether time of day can impact MRI or CT scan results. For this reason, simply talk to your doctor about the best time to arrive for your test if it has been scheduled for the future, and be sure to arrive early.
11. How Often Should We Do Stroke Scans?
Stroke is a life-threatening condition. A stroke scan should ideally be done as soon as symptoms start to determine the cause and start stroke treatment as soon as possible. Repeat scans may also be performed 48-72 hours after the stroke diagnosis to monitor the condition.
When to See a Stroke or Neurovascular Specialist
Stroke imaging provides valuable information, but understanding what the results mean and what should happen next often requires specialist assessment.
Consider seeing a specialist if you:
- Have experienced a stroke or transient ischaemic attack (TIA)
- Have abnormal findings on a CT, CTA, MRI or MRA scan
- Continue to have neurological symptoms despite normal initial imaging
- Have been diagnosed with carotid artery disease, a brain aneurysm or another cerebrovascular condition
- Have questions about whether additional imaging is needed
- Would like a second opinion regarding stroke diagnosis or treatment
- Need advice on long-term stroke prevention and recovery
A specialist consultation includes reviewing your brain imaging, identifying the underlying cause of your symptoms, discussing treatment options and developing a personalised plan for prevention, recovery and ongoing follow-up.
Seek emergency medical attention immediately if you experience sudden facial drooping, arm weakness, difficulty speaking, sudden vision loss, severe dizziness, loss of balance, confusion or a sudden severe headache. These symptoms may indicate a stroke or another serious neurological emergency requiring immediate treatment.
Find Out More about Stroke Tests, Screening, and Treatment in Singapore
A stroke can alter your life forever. If you suspect that you might be having one, Dr. Manish Taneja, our stroke specialist in Singapore is here to offer guidance. Contact us to arrange an appointment at our specialised stroke clinic in Singapore to find out more about stroke meaning, diagnostic imaging, treatment, and more.
Read More About Neurointerventional Treatments on Our Blog
To dive deeper into the types of neurointerventional treatments, head over to our clinic’s blog.
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Stroke Resources
We've Got You Covered for Specialized Stroke Screening, Prevention, and Management
Imagine heart attacks where the blood flow to your heart is blocked. Similarly, a stroke occurs when the blood flow to your brain is interrupted becoming a "brain attack". When blood supply does not reach a certain part, brain cells begin to die. Different types of stroke include ischemic strokes (blockage of blood vessel due to blood clot) or a mini stroke, a TIA (transient ischemic attack), with no permanent damage yet serious. Stroke also occurs when a blood vessel in the brain pops causing bleeding in the brain.
Certain areas of the brain can be affected by stroke and some symptoms of a stroke including cardiovascular disease, diabetes, and high blood sugar levels increase the risk of stroke whereas an active lifestyle or controlling high cholesterol reduces the risk. How well do you know stroke? Find tips to prevent and manage stroke, the differences in stroke screening tests, and the newer technology and treatments available. Come in for an easy consultation and further evaluation with our stroke specialist in Singapore at the Supreme Vascular and Interventional Clinic.
Stroke Prevention Tips: How to Avoid High Cholesterol
Controllable risk factors are lifestyle choices that can be changed to reduce the risk of having a stroke including managing your cholesterol.
We've Got You Covered for Specialized Stroke Screening, Prevention, and Management
Imagine heart attacks where the blood flow to your heart is blocked. Similarly, a stroke occurs when the blood flow to your brain is interrupted becoming a "brain attack". When blood supply does not reach a certain part, brain cells begin to die. Different types of stroke include ischemic strokes (blockage of blood vessel due to blood clot) or a mini stroke, a TIA (transient ischemic attack), with no permanent damage yet serious. Stroke also occurs when a blood vessel in the brain pops causing bleeding in the brain.
When a stroke occurs, the symptoms of stroke depend on how blood flow to the brain is affected. Individuals at high risk and even higher risk (family history) often have high blood pressure, atrial fibrillation, or another risk factor for stroke, all of which increase the risk of stroke. Disrupted blood flow can even damage the blood vessel in the brain and affect one side of the body. Having a stroke doesn’t mean it has to lead to permanent disabilities. Recognizing early warning signs is essential to reduce the risk, and in some cases, procedures such as carotid endarterectomy may help increase the blood vessel in the brain and restore healthy circulation.
Certain areas of the brain can be affected by stroke and some symptoms of a stroke including cardiovascular disease, diabetes, and high blood sugar levels increase the risk of stroke whereas an active lifestyle or controlling high cholesterol reduces the risk. How well do you know stroke? Find tips to prevent and manage stroke, the differences in stroke screening tests, and the newer technology and treatments available. Come in for an easy consultation and further evaluation with our stroke specialist in Singapore at the Supreme Vascular and Interventional Clinic.
Supreme Vascular and Interventional Stroke Programs
Neurointerventional / Stroke Treatments
The Supreme Vascular and Interventional Clinic is your "go-to" facility for various neurointerventional / stroke conditions and treatments. To arrange an appointment with Dr. Manish Taneja, our stroke specialist, contact us. You can also call us at (+65) 6904 8084 for a consultation.