MRI Scan is an imaging technique to visualize detailed internal structure and limited function of the body. MRI stands for Magnetic Resonance Imaging and it is most commonly used in radiology to create pictures of tissues, organs and other structures inside the human body using a strong magnetic field and radio waves.
MRI Scan is more useful in neurological (brain), musculo-skeletal, cardiovascular, and oncological (cancer) imaging as it provides much greater contrast between the different soft tissues of the body than CT Scan. MRI provides an unparalleled view inside the human body. The level of detail we can see is extraordinary compared with any other imaging modality. MRI is the method of choice for the diagnosis of many types of injuries and conditions because of the incredible ability to tailor the exam to the particular medical question being asked.
How does the MRI Scan work?
MRI Scan uses a powerful magnetic field to align the nuclear magnetization of (usually) hydrogen atoms in water in the body. Radio frequency (RF) fields are used to systematically alter the alignment of this magnetization, causing the hydrogen nuclei to produce a rotating magnetic field detectable by the scanner. This signal can be manipulated by additional magnetic fields to build up enough information to construct an image of the body. Sometimes contrast agents are injected to enhance the appearance of blood vessels, tumors or inflammation.
The MRI scanner is like a tunnel about 1.5 meters long surrounded by a large circular magnet. You will be asked to lie on a couch which then slides into the scanner. A ‘receiving device’ is then placed behind the part of the body being examined. This detects the tiny radio signals emitted from your body. When each ‘picture’ is being taken you need to keep still for a few minutes otherwise the scan picture may be blurred. The whole procedure can take 15-40 minutes. However, since the scanner is noisy, you will be given some headphones or earplugs to protect your ears from the noise.
Is MRI Scan safe?
Unlike X-rays or CT Scan, MRI Scan does not use radiation. Thus MRI Scans are painless and safe without any major side effects. However, some people do have reactions to the contrast dye used sometimes. Moreover, Patients with some metal implants, cochlear implants, and cardiac pacemakers are prevented from having an MRI scan due to effects of the strong magnetic field and powerful radio frequency pulses.
Further, Pregnant women are usually not advised to have an MRI scan unless it is urgent. Although the scan is thought to be safe, the long-term effects of strong magnetic fields on a developing baby are not yet known.
Overall MRI Scan is a safe procedure.