If you suspect acute cerebral infarction, should you check MRI or CT? Do you know?

In the medical field, when a patient is suspected of having acute cerebral infarction, choosing the right examination method is crucial for accurate diagnosis and timely treatment. Magnetic resonance imaging (MRI) and computed tomography (CT) are two common imaging examination methods. So, do you know whether to check MRI or CT when acute cerebral infarction is suspected? Let's take a deeper look.

1. What are the symptoms of acute cerebral infarction?

Acute cerebral infarction is a serious cerebrovascular disease, which is generally caused by local brain tissue hypoxia and ischemia due to blockage of cerebral blood vessels. The symptoms of acute cerebral infarction vary depending on the site of infarction and the manifestations are diverse. They usually manifest as paresthesia, where one side of the patient's body suddenly becomes dull in its ability to perceive temperature and pain, and some patients may also experience numbness of the tongue or face; movement disorders, where one side of the patient's limbs may suddenly become numb and weak, making it impossible to pick up objects, walk, run, etc. normally, and in severe cases may even lead to complete paralysis; speech disorders, due to the impact of cerebral infarction on the normal function of the language center, the patient may have problems such as slurred speech and inability to understand what others say; vision problems, the function of the patient's optic nerve may be affected by insufficient blood supply to the brain, and symptoms such as blurred vision and visual field defects may occur, and even blindness may occur; dizziness and imbalance, due to the impact of cerebral infarction on the area of ​​the patient's brain responsible for coordination and balance, the patient may feel dizzy and have unsteady standing and walking; cognitive and consciousness disorders, if the patient's acute cerebral infarction is more severe, symptoms such as loss of consciousness, memory loss, decreased cognitive function, and coma may occur.

2. What is the difference between MRI and CT examinations?

2.1 Imaging Principle

CT can quickly present a cross-sectional image of the patient's brain, showing the structure and lesions of the brain. It uses X-rays to perform a tomographic scan of the patient's body. Images are generated based on the differences in the absorption of X-rays by different tissues of the human body. Nuclear magnetic resonance has a higher resolution for soft tissues and can provide multi-parameter, multi-directional images. It generates images of the human body's interior with the help of its powerful magnetic field and radio waves.

2.2 Inspection time

MRI examinations usually take more than ten minutes or even longer, which is relatively time-consuming, while CT examinations can usually be completed within a few minutes, which is relatively fast. This is because CT can quickly obtain images and is suitable for preliminary examinations in emergency situations, while the MRI imaging process is more complicated and requires multiple scans and data processing.

2.3 Image Resolution and Detail Display

CT examination has a relatively low resolution for soft tissue, but it can better display the bony structure of the patient's brain. In the diagnosis of acute cerebral infarction, CT may not be able to clearly show early ischemic changes or small infarction foci. MRI can better distinguish soft tissue and clearly display brain tissues such as nerve fibers, white matter, and gray matter. Therefore, when diagnosing acute cerebral infarction, it can more accurately show the edema of surrounding brain tissues, as well as the degree, location, and range of infarction foci.

2.4 Effects on the human body

Since CT uses X-rays for examination, it has certain radiation risks. Normally, there is no need to worry about safety issues when performing a single CT examination because the radiation dose is within a safe range. However, special groups such as children and pregnant women need to consider CT examinations with caution. MRI uses radio waves and magnetic fields for examinations, and is generally safer. However, due to its strong magnetic field, metal objects may heat up or shift, so MRI examinations may be risky for patients with metal implants such as vascular clamps, metal dentures, and pacemakers.

3. Why do doctors prefer CT scans?

3.1 Rapidly rule out cerebral hemorrhage

The treatments for cerebral infarction and cerebral hemorrhage are completely different. Therefore, when doctors examine patients with acute neurological symptoms, they must first quickly determine whether the patient has cerebral infarction or cerebral hemorrhage. Cerebral hemorrhage appears as a high-density shadow on CT images, and normal brain tissue can be easily distinguished from it. Therefore, CT examinations can rule out the possibility of cerebral hemorrhage in a short period of time. Although cerebral infarction in the early stages may appear normal on CT images, or only show slight low-density changes, it is not easy to be found. However, after the doctor has ruled out cerebral hemorrhage through a CT examination, he can preliminarily suspect that the patient has suffered a cerebral infarction and conduct further examinations.

3.2 Assessment of disease severity

CT scans can, to a certain extent, assess the severity of acute cerebral infarction by showing the extent of the lesions and the gross structure of the brain. For example, if the CT image of a patient shows obvious cerebral edema or a large area of ​​cerebral infarction, it means that the patient has a more serious condition and timely measures should be taken for treatment. In addition, CT scans can also detect possible complications such as brain herniation, which can endanger the patient's life and require emergency treatment once discovered. CT scans can detect signs of brain herniation, which can buy precious treatment time for patients.

3.3 Check speed and device accessibility

For patients with acute illness, time is life. Choosing CT examination first can provide diagnostic information more quickly, so doctors can quickly make a diagnosis and develop a treatment plan. In addition, CT equipment is widely used in most hospitals, and its faster examination speed can help a large number of patients to be examined in a short time. However, MRI equipment is relatively less popular, and the examination time is longer, and you may need to make an appointment and wait.

3.4 Preliminary guidance for treatment decisions

Although CT examination may not be able to accurately show the infarct lesion in the early stage of acute cerebral infarction, it can provide doctors with some key clues to help guide initial treatment decisions. For example, to prevent further formation of blood clots, doctors can consider using anticoagulants, antiplatelet aggregation drugs, and other drugs to treat patients who have ruled out cerebral hemorrhage. In addition, doctors can also analyze the results of CT examinations, evaluate the patient's overall physical condition, and determine whether they are suitable for further MRI examinations or other treatment measures.

4. In what situations is an MRI examination necessary?

4.1 Suspected small vessel disease or early cerebral infarction

If the patient's CT scan results are normal, but the patient has mild neurological symptoms such as mild limb numbness, weakness, or transient ischemic attack, the doctor may recommend an MRI to rule out the possibility of small vessel disease or early cerebral infarction.

4.2 Assessment of the scope and extent of infarction

In some cases, doctors need to understand the impact of the infarct on the surrounding brain tissue, such as whether there is an ischemic penumbra, edema, etc. MRI can better evaluate these conditions through various imaging sequences such as FLAIR imaging and T2-weighted imaging.

4.3 Differential diagnosis

In some cases, patients may not show typical clinical manifestations and need to be differentiated from other diseases such as demyelinating diseases and brain tumors. MRI can provide more image information to help doctors distinguish cerebral infarction from other diseases.

In short, when acute cerebral infarction is suspected, doctors usually perform a CT scan first to quickly rule out cerebral hemorrhage, assess the severity of the condition, and initially guide treatment decisions. However, for some patients with complex conditions or who need a more detailed diagnosis, MRI examinations are also essential. Doctors will comprehensively consider and choose the appropriate examination method based on the patient's specific situation to ensure accurate diagnosis and timely and effective treatment.

【Image source: Baidu】