All About Magnetic Resonance Imaging

MRI is a cutting-edge form of radiological diagnosis that uses magnetic fields to produce detailed and clear images of the body’s internal anatomy.

Article Contents:

• How an MRI Scanner Works
• The Benefits of MRI
• Types of MRI Scanners
• Should You Be Afraid of the Procedure?
• How MRI Differs from CT and Ultrasound
• What Does an MRI Show?
• When Is an MRI Prescribed?
• When Is Contrast Used?
• Contraindications for MRI
• Preparing for an MRI
• How long does an MRI take
• How an MRI is performed
• Receiving the results

How an MRI Scanner Works

The physical phenomenon underlying the use of magnetic resonance imaging is called magnetic resonance. The essence of this physical law lies in the ability of the nuclei of certain chemical elements found in the human body to alter their energy potential when exposed to a strong magnetic field. The energy released during this process is captured by the imaging equipment and converted into an image on a computer screen.

The Benefits of MRI

Magnetic resonance imaging can be used to obtain a three-dimensional image of the examined area in three projections. During the procedure, the machine produces several slices. Their thickness can be set individually; it is usually between 2 and 4 mm.

Images obtained using a CT scanner.

By acquiring a large number of cross-sectional images, it is possible to examine the entire organ and detect even the slightest abnormalities or diseases.

Types of MRI Scanners

Modern MRI scanners are available in various models with different specifications.

All MRI machines can be classified as follows

Closed machines are more powerful and provide greater detail, although examinations on open MRI machines are generally considered more comfortable for the patient. If the patient does not have a severe fear of enclosed spaces and has no weight restrictions, it is recommended to perform the examination on a closed machine.

MRI is also classified based on the strength of the magnetic field, which is measured in teslas. MRI methods include:

• Low-field MRI — magnetic field strength up to 1.0 T;
• High-field MRI — magnetic field strength exceeding 1.0 T.

Low-field MRI does not provide clear and detailed images. Examinations using high-field MRI scanners allow for the most accurate assessment of the area being diagnosed.

Modern high-field MRI scanners

The DiMagnet Clinic is equipped with a Philips 1.5 Tesla closed MRI scanner. This machine produces images of the highest quality and detail.

Should You Be Afraid of the Procedure?

Some patients feel anxious before the examination. However, their fears are unfounded—magnetic resonance imaging is completely painless, and the effects of magnetic radiation on the body are safe.

Unlike other types of radiological diagnostics, MRI does not use ionizing radiation. Magnetic fields do not have a carcinogenic or mutagenic effect on the body’s cells. Magnetic resonance imaging can be performed as often as necessary.

How MRI Differs from CT and Ultrasound

Magnetic resonance imaging has many advantages over ultrasound and computed tomography.

Ultrasound provides a two-dimensional image of the area being examined, but does not provide a comprehensive view of soft tissues.

Computed tomography (CT) can match MRI in terms of image clarity, but has a number of serious contraindications; CT is often used to visualize hollow organs and bone structures, while MRI is much more effective at visualizing soft tissues.

What Does an MRI Show?

Magnetic resonance imaging is successfully used to diagnose conditions such as.

• Thyroid gland;
• Liver;
• Gallbladder and bile ducts;
• Pancreas;
• Kidneys;
• Spleen;
• Joints;
• Spinal cord;
• Blood vessels of the head, neck, and abdominal cavity;
• Pelvic organs;
• Soft tissues;
• Etc.

All of the above anatomical structures are clearly visualized on an MRI. The diagnostic results allow for the identification of abnormalities in the examined organs.

When Is an MRI Prescribed?

The wide range of applications for magnetic resonance imaging makes its use necessary in the following cases:

• The need to establish an initial diagnosis;
• Conducting a comprehensive examination;
• Preparation for surgical intervention;
• Monitoring the effectiveness of applied therapeutic and treatment methods.

In some cases, the choice of diagnostic method is made by the attending physician. Magnetic resonance imaging detects soft tissue diseases and injuries more frequently than other methods.

MRI is necessary for diagnosing the following conditions

• Neoplasms.

Magnetic resonance imaging allows for the precise determination of the boundaries and size of tumors, as well as the extent of their invasion into soft tissues. Other radiological diagnostic methods cannot show the condition with such clarity and detail.

MRI also allows for the nature of a tumor to be determined with a high degree of certainty. Malignant tumors have indistinct borders and invade surrounding tissue. Benign tumors are generally clearly demarcated from healthy tissue.

• Brain disorders.

The increased accuracy of magnetic resonance imaging allows for the visualization of anatomical structures such as the pituitary gland and the sella turcica. Contrast-enhanced brain MRI has also proven highly effective in diagnosing demyelinating diseases (e.g., multiple sclerosis, Parkinson’s disease).

Brain images obtained using contrast-enhanced MRI are exceptionally clear, as magnetic waves are weakly reflected by solid anatomical structures, and there are no artifacts from the skull bones in the brain image.

• Intervertebral disc disease.

The spine.

Magnetic resonance imaging is the only diagnostic method that allows for the visualization of intervertebral discs. Even modern diagnostic methods such as computed tomography can only show the space between the vertebrae, whereas MRI provides a complete picture of the disc’s condition and the possible presence of herniations and protrusions.

The use of MRI is not limited to the conditions listed above; it is used to detect and monitor a wide range of pathologies, congenital developmental abnormalities, injuries, and the effects of surgical procedures.

When Is Contrast Used?

Magnetic resonance imaging can provide a very high degree of image clarity. In most cases, the use of contrast is not required.

However, contrast agents may be used in the diagnosis of tumors and small anatomical structures.

Contrast agents are based on the rare earth metal gadolinium and are administered intravenously during an MRI scan.

Contrast agents for MRI are much better tolerated than similar agents used in CT. This means that the contrast material can be safely used in patients with renal disease and does not require a preliminary creatinine test, which is necessary for CT diagnostics.

Contrast-enhanced MRI is used in the following cases:

• Suspected neoplasia;
• The need for differential diagnosis of a malignant tumor;
• Pituitary gland examinations;
• The need to diagnose differentiated diseases.

Contrast-enhanced imaging provides a complete picture of the disease, its progression, and the effectiveness of the treatment being administered.

Contraindications for MRI

Although magnetic resonance imaging is a safe procedure, there are a number of absolute contraindications to this examination that preclude its use in such cases.

• The presence of pacemakers, neurostimulators, or insulin pumps;
• Vascular clips in the cerebral arteries;
• The patient’s inability to maintain a fixed position for various reasons;
• Early childhood (under 5 years of age);
• The patient weighs more than 130 kg and has a waist circumference of more than 150 cm;
• Early pregnancy.

There are also a number of conditions in which MRI is performed with caution:

• Severe pain, making it difficult for the patient to remain still for a long period of time;
• Fear of enclosed spaces;
• Mental disorders;
• The second and third trimesters of pregnancy.

The presence of various prostheses and implants in the patient’s body may be a contraindication for MRI if they are made of metals sensitive to magnetic fields. Most modern medical devices are made of titanium or other materials that are inert to magnetic fields. Their presence in the body does not interfere with an MRI.

Preparing for an MRI

In most cases, no special preparation is required for an MRI scan. For an MRI scan of the abdomen, retroperitoneal space, and pelvic area, the procedure should be performed on an empty stomach, and patients should avoid high-fiber foods, alcohol, and smoking the day before.

The use of a contrast agent during the procedure does not require any prior preparation or testing.

How long does an MRI take

The time required for an MRI scan may vary depending on the area being scanned.

• Knee joint — 20 minutes;
• Brain — 15 minutes;
• Chest — 30 minutes;
• Abdominal organs — 40–45 minutes;
• Pelvic organs — 40 minutes.

If a contrast agent is required, the procedure takes 15 minutes longer.

How an MRI is performed

Before the procedure, the radiologist asks the patient about any contraindications to the examination. The patient is asked to remove any metal accessories (such as clothing with metal fasteners), lie down on the examination table, and is placed inside the MRI scanner.

During the scan, it is strictly forbidden to move, as this may affect the clarity of the images obtained.

The scanning procedure.

High-field MRI scanners emit a fairly high level of noise, which can cause some discomfort for patients. Medical centers provide “Dimagnité” headphones. These play soothing music alongside the sound of the equipment in operation.

The CT scanner scans the patient’s body from various angles and immediately transmits the images to a computer screen. The radiologist begins interpreting the results even before the procedure is complete.

Receiving the results

Upon completion of the examination, the scan results are available immediately. Many of the images obtained are carefully reviewed by a radiologist. Detailed conclusions are drawn regarding both the normal anatomy of the examined area and possible explanations for abnormalities and pathology.

15–30 minutes after the procedure, the patient is given a CD containing the written findings and the images obtained.

Magnetic resonance imaging (MRI) is the most modern and safest form of radiological diagnostics, providing accurate and rapid results and allowing for a thorough examination of the area being studied; MRI helps detect many diseases and abnormalities even in the early stages of development.