Chiropractic Center
of Manassas, Inc.
Diagnostic Testing
Manassas Virginia Chiropractor
Dr. James Binning
Serving
Prince William County
Manassas
Manassas Park
Centreville
Gainesville
Chantilly
Fairfax
Northern Virginia
What is an EMG/NCV (Nerve) test?
What is a Bone Scan? (back to top)
Your doctor may order a bone scan to help diagnose subtle or hidden bone fractures that may not show up on a routine X-ray, such as a stress fracture. Bone scans can also help detect:
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Bone cancer
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Bone infections
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Arthritis
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Causes of unexplained bone pain
No special preparation is required on your part before a bone scan, though you may be asked to remove jewelry or other metal objects. You can eat or drink anything you like before the test.
As with most tests, tell your doctor if you're pregnant or think you might be pregnant. Bone scans aren't performed on pregnant women because of concerns about radiation exposure to the fetus.
A bone scan can be divided into two basic parts:
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The injection. You will receive an injection of tracers into a vein in your arm. You'll then wait about two to four hours to allow the tracers to circulate and be absorbed by your bones. You may be allowed to leave the health care facility while you're waiting. Your doctor will ask you to drink several glasses of water so you'll urinate frequently — this removes unabsorbed radioactive material from your system.
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The scan. During the scan, you'll be asked to lie very still on a table while a machine with an arm-like device supporting the gamma camera passes over your body and records the pattern of tracer absorption in your bones. This is painless. A scan of your entire skeleton takes about 30 minutes. Scanning a limited area of your body
These images especially are
helpful for examination of the brain, neck, spinal cord and soft tissues.
MRI often is used in the diagnosis of central nervous system disorders, such
as multiple sclerosis,
because of its high-resolution images of the brain and spinal cord's white
and gray matter. In addition, MRI can be helpful for evaluating joint,
ligament, muscle and bone problems.
You can eat normally and continue to take your usual medications before this procedure, unless otherwise instructed. You may be asked to remove your street clothes and given a gown and robe to wear or told to wear clothing without metal fasteners, such as sweats. Before the test, you will need to remove all accessories — watch, jewelry, hairpins. Also remove wigs, dentures and hearing aids. This is necessary so that metallic objects in these items won't affect the quality of the MRI picture and to prevent electronic items — watch, hearing aid — from being damaged by the magnets.
Tell the technologist if you have any metal or electronic devices in your body, such as metallic joint prostheses, artificial heart valves, implanted electronic devices, cochlear implants or magnets in your dentures. The presence of metal in your body may be a safety hazard or affect a portion of the MRI image.
You shouldn't receive an MRI scan if you have an implantable cardiac defibrillator or pacemaker. The strong magnetic field produced by the MRI unit may interfere with the pacemaker's function.
If you think you're pregnant, tell the technologist before undergoing MRI imaging because the effects of magnetic fields on fetuses aren't well established.
If you have any questions, ask your physician or MRI technologist.
Procedure
The MRI machine is a large magnet with a central opening. You'll lie down on a moveable table that slides into the opening of the magnet. Depending on the part of your body to be examined, a small coil may be placed around that portion being examined to receive the MRI signal.
A technologist will monitor you from another room, and you will be able to talk with the technologist by microphone. In addition, you may be allowed to have a friend or family member stay in the room with you.
The MRI machine creates a strong magnetic field around you, and radio waves are directed at your body. You will not feel the magnetic field or radio waves, and there are no moving parts around you.
You will hear repetitive tapping, thumping sounds or other noises during the MRI scan. These sounds come from the internal part of the magnet. Ear-plugs or music may be provided to help block the noise.
An MRI examination can take between 30 and 90 minutes. While the scan is taking place, breathe quietly but comfortably, without moving your head or body. Most people find that after several minutes of imaging they become quite relaxed and have few problems lying still for the duration of the examination. If you have a hard time lying still for the required period of time or are anxious about the enclosed space, you may be given a sedative. Some MRI units may be wider, shorter or open on all sides, which may be more comfortable for you. However, the quality of images taken from these systems may vary.
In some cases contrast agents are injected into your veins to enhance certain tissues or blood vessels in the images. These will be inserted into an arm or hand vein with the use of a needle connected to an intravenous line. These contrast agents are different than those used in kidney tests or computerized tomography (CT) scanning. They don't contain iodine and are less likely to cause an allergic reaction.
What is an EMG/NCV (Nerve) test? (back to top)
Electromyography is a test that measures muscle response to nervous stimulation (electrical activity within muscle fibers).
How the test is performed
For an EMG, a needle electrode is inserted through the skin into the muscle. The electrical activity detected by this electrode is displayed on an oscilloscope (and may be displayed audibly through a speaker).
Because skeletal muscles are isolated and often large units, each electrode gives only an average picture of the activity of the selected muscle. Several electrodes may need to be placed at various locations to obtain an accurate study.
After placement of the electrode(s), you may be asked to contract the muscle (for example, by bending your arm). The presence, size, and shape of the wave form -- the action potential -- produced on the oscilloscope provide information about the ability of the muscle to respond when the nerves are stimulated.
Each muscle fiber that contracts will produce an action potential, and the size of the muscle fiber affects the rate (frequency) and size (amplitude) of the action potentials. A nerve conduction velocity test is often done at the same time as an EMG.
Nerve conduction velocity (NCV) is a test of the speed of conduction of impulses through a nerve.
How the test is performed
The nerve is stimulated, usually with surface electrodes, which are patch-like electrodes (similar to those used for ECG) placed on the skin over the nerve at various locations. One electrode stimulates the nerve with a very mild electrical impulse.
The resulting electrical activity is recorded by the
other electrodes. The distance between electrodes and the time it takes for
electrical impulses to travel between electrodes are used to calculate the
nerve conduction velocity.
What is a CT Scan? (back to top)
CAT scan; Computed axial tomography (CAT) scan
Definition
Computed tomography (CT) a method of body imaging in which a thin x-ray beam rotates around the patient. Small detectors measure the amount of x-rays that make it through the patient or particular area of interest.
A computer analyzes the data to construct a cross-sectional image. These images can be stored, viewed on a monitor, or printed on film. In addition, three-dimensional models of organs can be created by stacking the individual images, or "slices."
How the test is performed
The
patient will be asked to lie on a narrow table (gantry) that slides into the
center of the scanner. Depending on the study being performed, the patient
may need to lie on his/her stomach, back, or side. If contrast media (dye)
is to be administered, an IV will be placed in a small vein of a hand or
arm.
Much like standard photographic cameras, subject motion causes blurred images in CT. Therefore, the technologist operating the scanner and supervising the patient will give instructions through an intercom when to hold one's breath and not move.
As the exam takes place, the gantry will advance small intervals through the scanner. Modern "spiral" scanners can perform the examination in one continuous motion of the gantry. Generally, complete scans will only take a few minutes, however, additional contrast-enhanced or higher-resolution scans will add to the scan time. The newest multidetector scanners can image the entire body, head to toe, in less than 30 seconds.
How to prepare for the test
The CT scanner has a weight limit to prevent damage to the mechanized gantry. Have the health care provider contact the scanner operator if you weigh more than 300 pounds.
Since metal is very, very dense, the x-ray beam has difficulty passing through it and results in errors in the involved constructed slices (artifact). Therefore, the patient will be asked to remove jewelry and wear a hospital gown during the study.
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Chiropractic Center of Manassas, Inc.
Ambassador Square
7505 Presidential Lane
Manassas, VA 20109
(703) 257-0100
Copyright 2005 Chiropractic Center of Manassas, Inc. All rights reserved.
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