|
|
| What is an MRI?* |
All of us experience some degree of anxiety before undergoing
medical tests. It is natural. Knowing more about the testing process
helps reduce anxiety while making you a better informed patient.
In July 1977 the first Magnetic Rsonance Image (MRI) was performed
on a human. The procedure took five hours.
To the relief of patients and technicians alike, progress and technology
have changed dramatically since this first exam. In the past 20
years thousands of machines have made the MRI a widespread diagnostic
tool of choice for many physicians.
An MRI is a noninvasive and highly accurate method of diagnosing
a broad spectrum of musculoskeletal disorders. An MRI is able to
view the body's internal structure through the use of magnetic and
radio fields. This view inside the body is with a level of detail
extraordinary to other imaging methods. |
| |
| What to Expect |
Athletes going in for an MRI can expect to have the test performed
at a hospital, clinic or diagnostic center. The procedure may take
anywhere from 20-90 plus minutes. You may be asked to changed into
a hospital gown, and you will need to lie very still on your back
on a table for the duration of the MRI.
The technician will proceed with the test from an adjacent room.
You will be able to communicate with the technician via an intercom.
As the test begins, the table moves into the MRI machine, which
resembles a giant cube. Depending on the test being performed, you
might go into the machine head first or feet first. The body part
that is to be examined is lined up, and the scan begins.
When the body part is being scanned, it is placed into a strong
magnetic field. The is magnetic field is incredibly powerful - powerful
enough to pull paperclips of papers, stethoscopes of physician's
neck, erase credit cards and even create a hazard if any metal equipment
is left in the room. Yet the forces for medical purposes with a
MRI have no known biological hazards. However, people with a pacemaker,
inner ear implant, red blood cell diseases, and respiratory disorders
and those who are pregnant or breast feeding are normally not tested. |
| |
| Magnets & Radios |
The magnetic field is created from radio waves equivalent to the
FM frequency. The magnetic field causes various protons to spin
about their axes and emit energy. After the radio pulse is turned
off, the protons emit energy as they gradually return to their equilibrium
state. This process must be repeated many times before a significant
number of signals are produced. These signals are detected by a
receiver, which assigns each signal a color. The colors are a spectrum
of white, gray and black. Each variation of the colors represents
a type of tissue in the body.
By using different combinations of radio frequency pulses and receiving
the returning signals, numerous images can be created. From the
images, a two dimensional or three dimensional map of the tissue
is made. The maps create picture "slices" of the body.
This is especially beneficial when a physician would like a clear
view on the inner workings of a joint, like the knee or shoulder.
From the images created, a technician is able to determine the contrast
between normal and abnormal tissue. |
| |
| Summing it up |
|
Listed are a few of the benefits of having and MRI performed:
— Visualize a torn ligament
— Visualize a soft tissue injury, i.e. meniscus
— Diagnose tendinitis
— Evaluate masses in soft tissue of the body
— Evaluate bone tumors and cysts
— Evaluate bulging or herniated discs in the spine
Some drawbacks to the MRI include:
— Tight space can induce claustrophobia
— Machine is very noisy
— Must lie still for 20 minutes or more
— Very expensive
MRI's cost far more than other diagnostic tools,but often they
are warranted when the history and clinical findings suggest that
further testing is necessary. This decision is at the discretion
of the physician whose care you are under. Yet it is often the
test of choice by physicians for detecting soft tissue injuries
when more conservative approaches have been exhausted.
|
| *By Beth Raitz, MS, ATC in NATA
News, November 2001; p 35-36. |
|