Oleh: Thalia Kaylyn Averil
Magnetic Resonance Imaging (MRI) is a non-invasive imaging method that produces very detailed 3D images of anatomy, such as blood vessels, muscles, bones and other organs. MRI uses radio waves and magnets to generate images, unlike X-ray examinations that use X-rays and can produce ionizing radiation. Patients can also be given a contrast agent which is usually inserted into the body through a vein to see a clearer picture of certain organs. This procedure is usually performed for disease detection, disease diagnosis, and treatment monitoring. The MRI machine will create a very strong magnetic field and also transmit radio waves. This machine is a large tube, but with narrow gaps so it may be a consideration for people with claustrophobia. MRI will make the atoms in your body align in the same direction because of a very strong magnetic field. After that, radio waves will be delivered to the patient so that the atoms move again and energy will be produced from the movement of the atoms. The MRI sensor will detect the energy produced and convert it into an image and will then be examined by
a radiology specialist.
MRI is used to visualize soft tissues inside the body. MRI can provide a clearer picture of body parts such as the brain, spinal cord, and nerves compared to X-ray and CT scan. MRI is also often used to depict injuries in the knee and shoulder. Aneurysms and tumors can be diagnosed using MRI because different parts of the brain containing white and gray matter can be distinguished with MRI. If a person requires repeat imaging for diagnosis or treatment, especially of the brain, MRI is more commonly performed because it does not involve radiation or X-rays. Functional Magnetic Resonance Imaging (fMRI) is a special type of MRI performed to study the architecture of the brain and see areas of the brain that are active or that use more oxygen when performing various types of cognitive tasks. This contributes to the understanding of how the brain is organized and may become a new benchmark for determining neurosurgical risk and neurological status. Functional MRI can also examine damage from head injuries or conditions such as Alzheimer’s disease. MRI can assist healthcare professionals in detecting tumors in the body and searching for signs of their spread. Doctors can sometimes determine the malignancy of a tumor using MRI because MRI can show the extent to which the tumor has invaded body tissue. Healthcare professionals can also use MRI to plan further cancer treatment, such as radiation or surgery. Certain tumors are very easy to find and identify with MRI, so MRI is most often used to:
- Brain and spinal cord tumors, both tumors can be seen more clearly if using MRI with
contrast - Primary bone tumor
- Soft tissue sarcoma
- Tumors that occur in the area around the pelvis, such as tumors of the ovaries, cervix,
uterus, bladder and prostate
Currently, Rumah Sakit Abdi Waluyo has the best facilities, such as MRI machines with 1.5 Tesla and 3 Tesla. However, what is the difference between the two? The unit of measurement for magnetic strength is “Tesla” and 1 Tesla is equivalent to 10,000 gauss so a 3T MRI has twice
the power of a 1.5T MRI. During an MRI scan, the amount of signal sent back by the body that is used to create the image is directly correlated to the strength of the magnetic field. Therefore, the image produced will become more detailed the stronger the magnetic field.
3T MRI is often used for imaging more complex body organs, such as the brain, blood vessels, muscles, and bones. 3T MRI can show a clearer picture of these organs because it has a stronger magnetic field. The movement of blood and fluids in the body can be depicted very clearly by 3T MRI. 3T MRI can also collect more accurate images in a shorter time due to its greater magnetic strength. However, the disadvantage of 3T MRI is that it often depicts features that are not actually present in parts of the body or what are usually called artifacts. Additionally, 3T MRIs produce more heat and noise than 1.5T scanners. In certain situations, the magnetic strength of a 3T MRI may be too strong for patients using iron or metal-based implants so patients with implants are recommended to use a 1.5T MRI. Before undergoing an MRI examination, there are several things to consider:
- MRI uses a very strong magnetic field, so patients who have iron-based implants must
notify their healthcare professional provider beforehand - Special ear protection may be required because the MRI machine can produce loud
sounds up to 120 decibels - Patients who have kidney failure and are receiving dialysis therapy are advised not to
undergo MRI with contrast if it is not absolutely necessary because it can cause other
complications. - Pregnant women are advised not to have an MRI with contrast, especially in the first
trimester because the fetus’s organs are still in the developing stage and the contrast can
enter the fetus’ bloodstream. - People with claustrophobia may find it difficult to endure long periods of time in an MRI
machine because of the narrow openings. However, the patient can be given distractions
to overcome the discomfort, such as anesthesia, covering the patient’s eyes, or playing
music for the patient.
Resources
- National Institute of Biomedical Imaging and Bioengineering. Magnetic resonance
imaging (MRI) [Internet]. Bethesda: National Institute of Biomedical Imaging and
Bioengineering; date of publication unknown [cited 2023 Nov 19]. Available from:
https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging
-mri - Mayo Clinic. MRI [Internet]. Rochester: Mayo Clinic; date of publication unknown
[cited 2023 Nov 19]. Available from:
https://www.mayoclinic.org/tests-procedures/mri/about/pac-20384768 - Johns Hopkins Medicine. Magnetic resonance imaging (MRI) [Internet]. Baltimore:
Johns Hopkins Medicine; date of publication unknown [cited 2023 Nov 19]. Available
from:
https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/magnetic-resonanc
e-imaging-mri - American Cancer Society. MRI for cancer [Internet]. Atlanta: American Cancer Society;
date of publication unknown [reviewed 2023 Aug 25] [cited 2023 Nov 19]. Available
from:
https://www.cancer.org/cancer/diagnosis-staging/tests/imaging-tests/mri-for-cancer.html - Cancer Research UK. MRI scan [Internet]. London: Cancer Research UK; date of
publication unknown [reviewed 2022 Oct 31]. Available from:
https://www.cancerresearchuk.org/about-cancer/tests-and-scans/mri-scan - Wood R, Bassett K, Foerster V, Spry C, Tong L. 1.5 Tesla magnetic resonance imaging
scanners compared with 3.0 Tesla magnetic resonance imaging scanners: systematic
review of clinical effectiveness [Internet]. Ottawa: Canadian Agency for Drugs and
Technologies in Health; 2011 [cited 2023 Nov 19]. Available from:
https://www.ncbi.nlm.nih.gov/books/NBK174467/
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