MRI Scan – Magnetic Resonance Imaging

Magnetic Resonance Imaging (MRI) is a groundbreaking medical imaging technique that provides detailed views of the internal structures of the body.

Unlike imaging methods that rely on ionizing radiation, such as X-rays or CT scans, MRI uses powerful magnetic fields and radio waves to produce high-resolution images.

These high-resolution images allow physicians to see inside the human body and access areas that would otherwise be impossible to analyze. It help diagnose diseases, such as tumors, infections, and inflammatory conditions.

Here is what an MRI scan looks like in Medicai online viewer

Test it below, give it a try to see how easy it is to visualize your MRI scans!

With the embeddable Medicai DICOM viewer, you can visualize MRI scans online, anywhere on web or in mobile apps. Your DICOM files are stored in your Medicai workspace, in your cloud PACS.

‍

‍

How does an MRI scan work?

MRI operates on the principle of nuclear magnetic resonance, leveraging the magnetic properties of hydrogen atoms in the body.

The MRI scanner leverages the fact that the human body is made up of approximately 66% water. Each tissue has its own water component and its percentage varies, while the areas affected by various diseases or problems change their structure compared to the healthy tissue around. The camera notices these small differences and presents them in the form of images.

The MRI scanner generates a strong magnetic field that temporarily aligns hydrogen atoms.[1]

Pulses of radio waves then disrupt this alignment, causing the atoms to emit signals as they return to their original state. These signals are detected by the scanner and processed into detailed two- and three-dimensional images using advanced algorithms.

This phenomenon allows the machine to observe how these nuclei are reassembled in normal positions and to transform these movements into 2D (two-dimensional) or 3D (three-dimensional) images.

Role of Contrast Agents

This imaging procedure sometimes requires the injection or ingestion by the patient of a contrast substance, the most commonly used for MRI bearing the name gadolinium. [2] Gadolinium improves the visibility of specific tissues and is particularly useful in detecting tumors, visualizing blood vessels, and identifying inflammatory or infectious conditions.

The only restriction is that breastfeeding women will not be able to breastfeed until fully eliminating the contrast substance from the body, i.e. within 24 to 48 hours.

What to Expect During an MRI

Before undergoing an MRI, patients are advised to wear loose, metal-free clothing and inform the medical team about any implants, claustrophobia, or pregnancy.

The magnetic resonance machine is a large medical equipment, consisting of a resonance tunnel, a mobile table, as well as the computer, the central processing unit of the whole assembly [3].

The patient sits on the mobile table and is inserted inside the resonance tunnel where the scan takes place. Throughout the test, which can last between 15 and 60 minutes, depending on the area examined and the number of images required, the patient must remain stretched and still – this ultimately influences the quality and clarity of the resulting images.

As a safety measure, the patient receives headphones with an active microphone, so she can communicate permanently with the medical staff. In addition, headphones protect the patient from the sound produced when the device is operating.

Applications of MRI Scans

MRI scan is one of the finest and most thorough medical imaging investigations currently available, being of real use in diagnosing a very large number of conditions located in many organs and parts of the body [4].

There are several types of MRI scan:

Cerebral MRI scan

Cerebral MRI scan allows a detailed analysis of the brain that proves useful in: identifying the effects that a stroke, trauma or certain degenerative diseases have on the brain, identifying and delimiting the areas that correspond to an affected function (such as speech, thinking, motility, etc.), allows the identification and tracking of the evolution of brain tumors.

Spinal MRI

This investigation provides essential information for the spine area: spinal anomalies and alignment, allows the identification of congenital or spinal abnormalities of the spine, damage or disease in the area of ​​the vertebrae, discs, bones and ligaments, identifying the causes of back pain , such as diseases of the intervertebral discs (degeneration, hernias) or fractures, allows to observe compression of the spine and nerves, their inflammations, various infections or tumors in the respective area.

Abdominal MRI

It is recommended for the identification of tumors or diseases in the area of ​​the abdominal organs, to check the condition and to affect the organs such as kidney, liver, pancreas, spleen, to identify internal abdominal hemorrhages or inflammatory bowel diseases.

Cardiac MRI and Vascular MRI

Recommended in the evaluation of the health of the heart, by observing in detail its anatomy, compartments, valves, observing the blood flow inside the heart and in the adjacent tissues; evaluation and follow-up of the effects of diseases and heart conditions, including coronary or congenital ones.

Chest MRI

Provides an overview of the chest, including the heart and blood vessels in its area; allows detection and tracking of tumor evolution or of pericardial disease and of the mediastinal as well as pleural lesions.

Pelvic MRI

Provides important information about the pelvic area and muscles in its three compartments (anterior, middle and posterior), allowing the identification of disorders and afflictions.

Gynecological MRI

Provides an overview of the reproductive tract, but can also be done during pregnancy. Fetal Magnetic Resonance Imaging is a type of analysis that is done following an obstetrician doctor’s recommendation to evaluate risk of disease or to follow the evolution of a problematic fetus during pregnancy.

Breast MRI

Is a complementary procedure for mammography and mammary ultrasound. It is recommended by doctors especially when there are certain signs that the person in question suffers from a serious condition, such as breast cancer, but also to identify possible causes of problems such as unusual nipple leakage, dense breast tissue (when a mammography is not conclusive), metastatic axillary adenopathies with the breast as starting point, or even if there is suspicion of a breast implant rupture.

Urological MRI

The prostate is one of the frequently affected organs, which is why such a medical examination can provide a complete picture, allowing the creation of an appropriate treatment plan.

Magnetic resonance angiography

It’ s an advanced technique that enables the doctor to track the blood flow through blood vessels in order to detect any abnormalities. This type of MRI scan has a wide applicability: vascular aneurysm, vascular thrombus, partial rupture of the vascular wall, arterial occlusion, to identify atheroma plaques (in atherosclerotic diseases), preparation and evaluation of the patient’s evolution in case of stenting.

Oncological MRI

Used in detection of different tumors, as well as their evolution over time and during treatment, it is a major benefit for patients and physicians as it enables access to very sensitive parts of the body such as the brain. An MRI can provide the actual location of the tumor, as well as its size. This type of analysis is recommended instead of CTs because it is much safer for the patient and much more accurate. Although most cancers can be detected using an MRI, it is especially recommended for:

• Bone cancer
• Brain cancer
• Soft tissue sarcoma – skin cancer, uterine cancer, stomach cancer, etc.
• Blood cancers
• Cervical cancer – in its early stages
• Bladder cancer

Patient safety

Unlike other types of imaging analysis, Magnetic Resonance Imaging is one of the safest for the patient, as it is not subjected to harmful radiation. [5]

However, there are a number or safety procedures to be followed by patients: [6]

• The doctor should be informed about the general state of health, the existence of implants such as stents, cardiac stimulators or defibrillators or neurostimulation systems
• Also, the doctor should be informed about cochlear implants or any heart valve replacement surgery
• Pregnant women should notify the doctor even if there is no evidence that the analysis itself affects the fetus or pregnancy
• People with tattoos may feel a certain warmth over the tattooed area because some of the inks used in the tattoo industry may contain metallic pigments with no other side effects.
• Claustrophobic persons may require the administration of a very weak sedative, in order to maintain calm during the scan. In addition, the patient can always talk to the doctor if needed
• Dental implants are not affected by the MRI’s magnetic field because they are usually made of non-ferrous materials such as ceramics or titanium, which is are not magnetic. Patients should be aware, however, that stainless steel or chromium-cobalt implants can also cause discomfort
• The contrast substance generally used is not allergenic, as it sometimes happens with CT scans
• Also for the patient’s safety and the accuracy of the images obtained, the patient must remove any metal elements before the scan, such as: jewelry, watches, glasses, clothing with metallic elements – buttons, staples, zippers, accessories – or any electronical devices.

The Benefits of an MRI (Magnetic Resonance Imaging)

• MRI Scan procedure is non-invasive
• No harmful radiation is emitted
• Can be done at all ages
• It provides very precise images, which decisively contributes to establishing a correct and rapid diagnosis [7]
• It is effective in identifying a large number of disorders, from cancer to heart disease or abnormalities
• It has access to areas that would otherwise not be properly investigated

Advantages of MRI Over Other Imaging Methods

Unlike X-rays or CT scans, it does not use ionizing radiation, making it a safer option for many patients.

The high-resolution images produced by MRI provide unparalleled detail of soft tissues, making it especially valuable in neurological, musculoskeletal, and abdominal imaging.

MRI also allows for multi-planar imaging, offering comprehensive views of the area being examined.

Additionally, advanced techniques such as functional MRI (fMRI) and MR angiography (MRA) enable the assessment of brain activity and visualization of blood vessels, respectively.

Difference between MRI vs CT scan?

The main difference between MRI and CT scans lies in their imaging techniques and applications:

Imaging Technique

The enclosed design of the scanner may cause anxiety or claustrophobia in certain individuals, though open MRI options are available.

MRI (Magnetic Resonance Imaging): Uses a large magnet, radio waves, and a scanner table to create detailed images of the body. MRI relies on the magnetic properties of tissues and is particularly useful for imaging soft tissues, such as the brain, muscles, and ligaments. It is a painless procedure and often used in research for frequent imaging due to the absence of ionizing radiation.

CT (Computed Tomography) Scan: Uses X-rays to create detailed cross-sectional images of the body. It is particularly effective for imaging bone structures, detecting tumors, and guiding biopsies. CT scans provide quick results and are widely used in emergency situations.

Contrast Agents

MRI with Contrast: Sometimes requires an injection of a contrast agent to enhance the visibility of certain tissues or blood vessels. This is especially useful in body MRI and brain imaging.

CT with Contrast: Also uses contrast agents to highlight specific areas, but the contrast material used in CT scans is different from that used in MRIs.

Applications

MRI: Preferred for detailed imaging of soft tissues, brain, spinal cord, and joints. It is used for diagnosing conditions such as brain injuries and tumors.

CT Scan: Preferred for quick imaging of the chest, abdomen, pelvis, and detecting bone fractures. It is commonly used to diagnose injuries from trauma, cancer, and cardiovascular diseases.

Safety and Risks

MRI Safety: Generally safe but not suitable for patients with certain medical devices, like pacemakers, due to the strong magnetic field.

CT Scan Safety: Involves exposure to ionizing radiation, which can be a concern with frequent imaging, but is safe when used appropriately.

Both MRI and CT scans are essential tomography techniques in medical imaging, each with its specific advantages and best-use scenarios.

Their results consists of a series of standardized medical images, which can be saved locally or in a cloud PACS for later analysis or comparison with other studies using a DICOM viewer.

Considerations and Limitations

While MRI is a powerful diagnostic tool, it is not without limitations.

The cost of MRI scans is typically higher than that of other imaging methods, which can be a barrier for some patients.

The enclosed design of the scanner may cause anxiety or claustrophobia in certain individuals, though open MRI options are available.

Patients with metal implants, such as pacemakers or cochlear implants, may not be eligible for MRI due to safety concerns.

Additionally, the length of the procedure may not be ideal for emergency situations where quicker imaging methods are required.

References

[1] – https://www.nhs.uk/conditions/mri-scan/
[2] – https://www.osc-ortho.com/services/open-mri/mri-frequently-asked-questions/what-is-an-mri-with-contrast-why-do-i-need-contrast-is-it-safe/
[3] – https://www.webmd.com/a-to-z-guides/what-is-a-mri#2-5
[4] – https://www.ismrm.org/resources/information-for-patients/#What%20is%20MRI%20used%20for
[5] – https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging-mri#pid-961
[6] – https://stanfordhealthcare.org/medical-tests/m/mri/risk-factors.html
[7] – https://www.fda.gov/radiation-emitting-products/mri-magnetic-resonance-imaging/benefits-and-risks