MRI scan is a non-invasive computerized medical procedure that uses magnetism, along with radio waves, to scan the body and obtain two-dimensional and three-dimensional images of anatomical structures.
These high-resolution images allow physicians to see inside the human body and access areas that would otherwise be impossible to analyze. MRI scan principle is based on the phenomenon of nuclear magnetic resonance, much more secure than that based on the use of ionizing radiation, as is the case with radiographs or CT scans.
What is MRI Scan and how does it work?
The Magnetic Resonance Imaging machine produces a magnetic field that, together with the radio frequency, temporarily alters the normal alignment of hydrogen atoms in the body. [1]
This phenomenon does not have negative effects, it only 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. 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.
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. It enables the MRI scanner to obtain clearer and more crisp images, without presenting any additional risks. [2]
The only restriction is that breastfeeding women will not be able to breastfeed until fully eliminating the contrast substance from the body, ie within 24 to 48 hours.
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.
What kind of conditions can be diagnosed with an MRI?
MRI scan is one of the finest and most thorough medical 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.
MRI of heart and blood vessels (cardiac or vascular)
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, accesories – 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
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
