Magnetic Resonance Imaging (MRI)
What is MRI?
Magnetic resonance imaging (MRI) is a noninvasive method of recording the internal structure and certain aspects of function within the body with the use of nonionizing electromagnetic radiation. Its application, which was initially limited to only certain specific systems, is now used to depict function as well as anatomy of all regions of the body and also has a high sensitivity to the presence of disease.
How does MRI work?
The MRI machine uses radiofrequency (rf) radiation in the presence of carefully controlled magnetic fields to produce high quality cross-sectional images of the body in any plane. It gives a more accurate picture of the structures in the body that are filled with fluids and is sometimes preferred over other techniques of imaging.1
When is MRI advised?
In the recent years, with the advent in the scanning techniques and the improvement in the associated materials, MRI is being advised for detecting a wide array of disorders. Some of the conditions for which MRI scanning may be advised include:
- Detection of tumors in the skull, chest, abdomen or pelvic region.
- Detection of various disorders of the heart such as coronary artery disease, evaluation of the damage caused by a heart attack or progressive heart disease.
- To detect tumors and other abnormalities in the human reproductive organs, such as uterus, ovaries, testicles or prostate.
- To detect abnormalities in the liver and other similar organs.
- Disorders of the blood vessels of the chest, abdomen and pelvic region.
Magnetic resonance angiography is the modified version of the MRI wherein the blood vessels can be studied in a detailed manner to detect any abnormalities that affect the normal functioning of the blood vessels.1,2
What is the preparation required for MRI?
There are certain precautions, which need to be taken before undergoing MRI, as the procedure involves exposure to high intensity magnetic field. One should not have any metal and electronic objects (such as jewellery, watches, pins, credit cards, etc.,) with him or her while undergoing the scan. Individuals with pacemakers, ear implants and clips placed within certain blood vessels should not undergo this procedure as it affects the functioning of these. An individual should always inform the doctor if he or she has undergone any such treatments or is suffering from any other disorder/condition.
The individual who is undergoing the scan may be asked to wear a gown and the procedure generally lasts for about 15–30 minutes depending on the type of scan required. If a dye is required then it may be: injected through a vein, given as a drink or instilled through the rectum based on the part or organ being scanned. The individual is required to lie on the table, which moves gradually into the scanning machine and the individual should lie still until the scanning is completed.2
What are the complications of MRI?
In most of the cases, MRI scanning is not associated with any adverse effects. In some cases, it may cause allergic reactions when a dye is used.
1.Wilkinson ID, Paley MNJ. Magnetic Resonance Imaging: Basic Principles. In: Adam A, Dixon AK (eds). Grainger & Allison’s Diagnostic Radiology. 5th edn. Philadelphia: Churchill Livingstone, 2008.
2.Radiologyinfo. MRI of the Body (Chest, Abdomen, Pelvis) [homepage on the internet]. Oak Brook, IL: Radiological Society of North America, Inc. Available at: http://www.radiologyinfo.org/en/info.cfm?pg=bodymr. Updated on: 3 July 2007, Accessed on: 6 Jun 2008.
Date last updated: April 18, 2015