Testing, Testing!

You want me to get what kind of test?! Have you ever gone to the doctor’s office after getting injured and the doctor wanted to send you for some odd sounding test? What do those letters mean? Will it hurt? How long will it take? These may be some of the questions running through your mind. There are many kinds of diagnostic tests that doctors can use to help them make a proper diagnosis of an injury. These can range anywhere from an X-ray to a CT scan. The following gives a brief explanation of some of the more commonly used tests to diagnose musculo-skeletal injuries.

An Arthrogram is the visual study of a joint by injecting the joint with an opaque dye. Sometimes air is also injected along with the dye, depending upon the joint that is involved. The joint is then X-rayed. This test can show disruption of soft tissue and loose bodies in the joint and usually takes about an hour to perform.

A Bone Scan involves the introduction of a radioactive tracing dye(which is harmless) into the body intravenously. After the injection, you have to return in 3 hours for the dye to be read. This dye is detected when imaging of the body is done. The dye will show up in an area where bone formation is occurring faster than the surrounding bone(because of healing in that area). Bone abnormalities such as stress fractures can be detected through this test.

CT scan or CAT scan (Computerized Axial Tomography) was developed in 1972. It is a diagnostic test that can scan the body in many different angles. This is done with a X-ray that takes cross-sectional pictures of the body. The electrical signals are sent back to the computer for comparison and then processed into a visual image. In each of these pictures, the body is seen as a cross-sectional X-ray “slice” of the body. Occasionally, dye is also injected in to the body to further enhance the structural images. A CT scan is very similar to an MRI , but the images are not as clear as an MRI . However, a CT scan is much cheaper than an MRI .

EMG-Electromyography is a test performed to evaluate the peripheral nervous system and muscle activity. Normally, a muscle is “electrically silent” at rest, but when it is active as during a contraction or stimulation, an electrical current is generated. A very thin electrode needle is inserted into the involved muscle. The electrode measures the activity of the muscle at rest. A nerve conduction test may then be performed when a non-invasive stimulator, also attached to the skin, sends a brief impulses to a nerve, the nerve then transmits the impulse, and a response is recorded by electrodes some distance away. These are observed on an oscilloscope or on a graphic recording called an electromyogram. In nerve disorders, there is usually increased spontaneous activity during relaxation and decreased, altered, or absent reactions when stimulated or contracted.

Magnetic Resonance Imaging , otherwise known as MRI , was first used in the late 1980’s. It is another tool used by doctors to explore the body for an injury. An MRI scan can detect muscle and ligament tears as well as bone abnormalities. An MRI scan takes 45 minutes to an hour to complete. The test is performed by laying on a table that slides into a tube that covers the body either part way or completely. This can be a problem for people who are claustrophobic, and also some larger people. Open MRI machines are also used to better accommodate larger people and people with claustrophobia.

The test works by surrounding the body with powerful electromagnets, which creates a strong magnetic current that focuses on hydrogen atoms in water molecules and aligns them. When the current is shut off, the atoms continue to spin which emit an energy that is detected by the computer. The hydrogen atoms in different tissues spin at different rates, producing different images. These images are shown as a cross-sectional “slice” of the body just like a CT scan, but the clarity of the images is much greater.

A Myelogram is a test for disorders of the spinal cord and nerve roots. A contrast dye is injected into the spinal canal prior to the test. The dye will outline the spinal cord and its nerve roots on an X-ray. This test usually takes 1-2 hours. Different conditions such as disk disease, tumors, nerve root compression, and other diseases can be detected with this test.

X-rays are the most common test performed by a physician to detect injury. It usually takes approximately 20 minutes to perform. X-rays are generally done to detect a fracture, dislocation or other defect in a bone, but can in some cases show presence of arthritis. The different tissues of the body absorb X-rays in a certain way. Bone is more dense and absorb X-rays better than soft tissue, which is made mostly of water. The body part that is X-rayed is placed between a piece of film and a tube which makes the X-rays. The X-ray tube is turned on briefly to expose the film. The bones absorb most of the X-rays and will appear white on the X-ray film. X-rays penetrate through the soft tissue to expose the film underneath and turns the soft tissue dark grey on the X-ray film. A fracture is seen as a break in the normally smooth contour of the bone. If you have any questions about these or any other tests, please contact Guilford Orthopaedic and Sports Medicine Center.