MRI 13 of 14

Today there is information and images about:

1. The MRI Exam
2. Screening
3. The Imager

The MRI Exam

Your MRI exam may not proceed exactly as described here, but it will be similar enough so that this description will help you prepare for your exam.

Your MRI will be performed at a location which will be referred to as the MRI Center.  When you first arrive at an MRI Center, you will report to the reception/waiting room.  

 Here you will check in and fill out any necessary paperwork for your exam.

Jewellery, watches, coins, keys, and credit cards are incompatible with the magnetic resonance imaging procedure.

 You will need to leave these items at home or leave them in a locker provided in a dressing room at the MRI Center. These objects can be attracted by the magnet on the imager or distort the images. Here is a picture of a metal belt buckle being attracted by the magnetic field of the imager.   

   

There is clearly a large force pulling the belt buckle into the magnetic field. Alternatively these objects can inhibit radio frequency waves from getting into the body and thus produce distorted images.  Certain articles of clothing, such as metal zippers, rivets, wires, and belt buckles, are incompatible with the imaging procedure for the same reasons.  

 

 You will need to leave these items of clothing in the lockers and change into an imaging gown which contains no metal.

The MRI Center also has nursing, scan, control, computer, and reading rooms. You will only see the nursing area  

 

if you require special nursing assistance, for example if you have an intravenous line for medication.  The scan room is where the imager is located and is where you will be for your exam.

 The technologists operate the imager from the control room.

The computer room is where the imaging hardware and computer are located.  

The last room is called the reading room.   

This room consists of large light boxes on which a radiologist will read your images.

In addition to the receptionist who greeted you when you arrived, there are many individuals working as a team to make your MRI exam happen. A MRI nurse will take care of your nursing needs which might include administration of any medications or contrast agents that you may need. A MRI technologist will interact with you during your scan. The technologist will take you in and out of the scanner as well as operate the scanner. A radiologist will prescribe which imaging sequences are to be used to record the magnetic resonance images, and will read or interpret the images. Many other individuals work behind the scenes to make the center functions properly. You will most likely not meet these individuals, but they include the custodial staff, service engineers, and scientists, all of whom keep the imager clean and functioning properly.

Screening

Certain anthropogenic, or man-made objects are incompatible with the radio frequency waves and magnetic fields used in magnetic resonance imagers. You left some of these objects, such as keys, pens, and zippers, in your locker or at home.  

Other objects which may have been placed inside of your body, or certain medical conditions, may also be incompatible with your MRI exam. The process of identifying these contraindicators, as they are called, is called screening. The MRI personnel will ask you many questions to determine if you can safely be imaged.  You will also be asked you weight and height.  This information will allow the pulse sequence to adhere to the specific absorption rate (SAR) limitations, and the proper choice of imaging hardware.  

Do you have...

a cardiac pacemaker? yes, no

an intracranial aneurysm clip? yes, no

dentures/partials? yes, no

a hearing aid? yes, no

a hair piece? yes, no

Scan Related

Height ______

Weight ______

Are you able to lie flat? yes, no

Contrast Agent

Have you ever had IV MR contrast (Gadolinium)?
yes, no

Is there a possibility of pregnancy? yes, no

Surgery

Have you had brain or head surgery? yes, no

Have you had ear surgery? yes, no

Have you had eye surgery? yes, no

Have you had other surgery? yes, no

Have you had artificial implants? yes, no

History

Anemia: yes, no

Seizures: yes, no

Kidney Disease: yes, no

Asthma: yes, no

Bullets, Shrapnel, BB: yes, no

Pierced body parts: yes, no

Hx of metal fragments in eye: yes, no

Other

Drug allergies/reaction: ____________

If you have a pacemaker, you should not be imaged because the pacemaker will not function in the magnetic field of the imager.  If you have metal filings, shrapnel, or ferromagnetic clips or pins in your body, you probably will not be imaged.  These objects could be twisted by the magnetic field and cause serious injuries.  Most new surgical metal implants are made of a high quality stainless steel which is non magnetic. You can be imaged with these, provided they are not in the anatomy being imaged.  Dental fillings and bridgework are okay, but some bridgework may prevent the radio frequency waves from getting into the body if the head is imaged.

The Imager

You will be imaged inside a long tubular hole approximately 60 cm (24 inches) in diameter.

If your feet or knees are being imaged, your head will be outside of the magnet.  If your head, shoulder, or chest is being imaged, your feet will be outside of the imager.  Some claustrophobic individuals get anxious in situations like this, but be assured that you are in constant intercom contact with the technologists in the control room and can get out at any time. Some imaging sites will allow a friend or relative to accompany you through your scan. This individual may sit in the scan room while you are being imaged and talk with you.

When you first lie on the bed of the imager, the technologist will position an imaging coil around the anatomy being imaged, 

 in this example a head coil. The technologist will the move your body to position a specific piece of anatomy at a crossed light beam. This spot on your body will be advanced to the isocenter of the magnet before the scan begins. This process is called landmarking.