how mri work

MRI stands for Magnetic Resonance Imaging. It is a relatively new method to enable doctors to determine structures inside the human body without cutting it open. The technology was originally used to study the structure of chemicals and has lately been adapted to create images of the insides of living bodies. MRI is painless and safe for most people. It is an important advance in man’s search for better healthcare.

The human body is made of small units called atoms. Atoms are the basic building blocks of all materials and substances in the universe. Atoms are subject to magnetism. The atoms that make up the human body align themselves in a particular way when the body is placed in a magnetic field. Radio waves disturb such an alignment. Hence, the switching on and off of radio waves inside a magnetic field with a human body causes the atoms to release energy or to resonate.

Hydrogen atoms, which are most common in human bodies, are particularly sensitive to magnetic fields and to radio waves. The reaction of each part of the body to magnetic fields and to radio waves is distinct. Computers, linked to sensitive antennae, are programmed to interpret such energy release, to produce images of structures inside the body. Such images are of both hard tissues such as bones and of soft parts such as muscles and organs. MRI can also create images of blood flow and clots.

The images can be of the front of the body divided from the back, the left divided from the right and the upper half separated from the lower half. These three views can be combined to show strands of connective tissue that run at angles within the body. A doctor can see images of the body using MRI that are more informative and useful than images produced by older methods such as X Rays. Dyes may be injected into a patient to get sharper images.

The MRI process takes about an hour. The patient has to lie on a table. The latter is moved into a magnetic field that has arrangements to receive radio signals. The original MRI design required patients to lie inside a closed chamber and this made some of them uncomfortable. The latest MRI machines have an open magnetic field so that the patient is more comfortable.

However, both old and new systems require patients to lie still for the duration of the test. MRI equipment is relatively expensive. Patients without insurance can rarely afford the test. Images are distorted by artificial implants in the body. Patients have to remove all metal objects before they go near an MRI machine.

Heart patients with pacemakers cannot use MRI. Credit cards will not work once they have been taken near an MRI machine. We do not know enough about the effect of MRI on a fetus; therefore women who are expecting are not subject to MRI unless there is a pressing need. Though there are some people for whom MRI is not suitable, it does offer unique benefits and can help save lives.

Research into new applications of MRI is in progress. The functioning and diseases of the brain is a subject of particular importance. Many medical conditions and diseases that could not be understood or treated earlier have become easier to manage thanks to MRI.

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