These particles produce signals due to Radio waves that are collected by a receiver within the scanner. These signals are characterized with the use of varying magnetic field and are further processed by a computer in order to create ultra sharp images of tissues in the form of "slices" that can be viewed in any plane and from any direction.
The key advantage of MRI is that it causes no pain and the responsible magnetic fields cause no damage of any kind to human tissues. The MR scanner used may generate considerably loud tapping or knocking noises during the process but it can be prevented using earplugs. A patient can easily communicate with the technologist or radiologist at any instant with the use of an intercom.
The magnetic field generated in the MR system is quite powerful and will attract Ferro-magnetic objects and can cause them to move suddenly and with a considerable force. Thus, there can be a risk to the person in the flight path of the object. Due to this reason, great care is taken and ferromagnetic objects like screwdrivers and oxygen tanks are not allowed into the MR system area. A patient is asked to remove all kind of metallic belongings like watches and jewelry before going for an MRI.
The magnetic field of the MR system is of considerable magnitude and can pull on any iron-containing object in the body like medication pumps or aneurysm clips. Every MRI facility has a strict protocol that ensures that the MRI technologist and radiologist know about the presence of all metallic implants and materials so that special precautions can be taken. Sometimes, even the exam may have to be canceled. In case a bullet or other metallic fragments are present in the body, there is a risk that it could change position leading to an injury. A metallic implant can not only distort the MR images but also make it difficult for the MRI system to tune to your body. It is not possible to avoid it but allowance can be made while interpreting the images only if the radiologist is aware of their presence.
Some MRI examines a gadolinium that may be injected into a vein in order to help the interpretation. a gadolinium is a contrast agent that does not contain iodine like those materials which are commonly used in x-ray process and hence rarely causes any problem or allergic reaction.
Preparation for MRI
The patient is asked to wear a special gown during the MRI study. The person (generally a friend or relative) accompanying you will be asked questions regarding the presence of implants and will be instructed to remove all metal objects from pockets and hair even before entering the room. A screening form is filled to ensure that the patient may safely enter