What Is Imaging?
Imaging is the use of technologies to create and display pictures of a patient’s musculoskeletal system without having to operate. Imaging studies are useful for the diagnosis of many conditions both within orthopedics and in medicine as a whole. There are many types of diagnostic imaging that use different types of technology to visualize different aspects of the musculoskeletal system.
Types of Imaging
Different types of imaging are used for different purposes. Some are better at showing certain types of tissue. Some are less powerful but less expensive to perform. Some enable doctors to visualize nearly all types of musculoskeletal tissue but require prior authorization from patients’ insurance carriers.
Some of the most commonly used types of imaging studies used in orthopedics are:
X-rays: X-rays are some of the most widely used imaging studies in existence. They are a form of electromagnetic radiation in the same family as ultraviolet light (sunlight). The calcium in bone absorbs most of these rays, making X-rays an ideal method of diagnosing fractures and other bone abnormalities.
The same feature that makes X-rays so useful for visualizing bone also makes it unsuitable to display other types of tissue (e.g., muscle, tendons and ligaments). The calcium in bone absorbs too much of the X-rays for soft tissue to be clearly visible.
Another disadvantage to X-rays is that both patients and technicians are exposed to ionizing radiation. While the doses of radiation are miniscule, ionizing radiation is known to cause tissue damage. Most patients will never be exposed to dangerous levels of radiation from X-rays alone.
Computed tomography: Computed (or computerized) tomography (CT) scans are series of X-rays taken from different angles and put together. In a standard X-ray, the rays are beamed from a fixed position. During a CT scan, an X-ray slowly rotates around a patient’s body, making for a much more complete internal view. A computer then assembles these individual X-rays into a composite picture.
Because CT scans use multiple X-rays, a patient’s exposure to radiation is compounded. However, even with CT scans patients will not generally be exposed to enough ionizing radiation to cause damage.
Magnetic resonance imaging: Magnetic resonance imaging (MRI) scans are similar to CT scans in that they produce a 360-degree view. However, MRIs do not use radiation such as X-rays and CT scans. Instead, magnetic vibrations are used and interpreted by a computer.
The patient lies motionless in the MRI machine. The machine creates a magnetic field, then pulses radio waves through the area of the body to be imaged. These waves cause tissue in the body to vibrate. A computer then measures the rate of vibration and translates them into a two-dimensional picture.
Because the patient must lie as still as possible for half an hour or more, MRIs can sometimes be uncomfortable. MRIs are not recommended for patients with pacemakers or metal implants because of the powerful magnets used.
Ultrasound: Ultrasound, also known as sonography, uses sound waves to develop a picture of the internal human body. Ultrasound uses high-frequency sound waves beamed into the body. These sound waves are bounced back by internal body structures and picked up with a probe, then translated into pictures. Ultrasound is especially well-suited to displaying soft tissue such as ligaments and tendons.
Bone scan: A bone scan is a nuclear imaging test, useful for bone pain that could not be identified by an X-ray. Tiny amounts of radioactive materials called tracers are injected into a person. When using special scanning equipment, tracers highlight areas of the body that are actively repairing themselves, yielding clues as to the nature and location of pain. The amount of radiation used is exceedingly small so bone scans are safe and carry no adverse effects.
Dual-energy X-ray absorptiometry: These scans, known as DXA (or DEXA) scans, measure bone density. Bones continually lose mass and rebuild themselves throughout the lifespan. Osteopenia, which progresses to osteoporosis, is when bones lose more mass than they gain. DXA scans use two X-rays set to different levels of intensity to measure bone density and check for the presence of osteoporosis.
How Imaging Is Used
Doctors use imaging studies to assist in making diagnoses. For many conditions, a physical exam and medical history are sufficient to make a diagnosis. However, due to many conditions sharing symptoms, imaging is often necessary or at least helpful in confirming a doctor’s suspicions about what ails a patient.
An X-ray is usually the first imaging test ordered. X-rays are often required by patients’ insurance companies before more expensive studies such as MRIs or CT scans. Even when a soft tissue injury such as a muscle strain or ligament sprain is suspected, X-rays are useful to rule out other sources of pain or disability, such as fractures.
MRIs and CT scans enable better visualization of soft tissue such as tendons, ligaments and cartilage. After X-rays come back, one of these types of imaging studies are often the next step when an orthopedist believes the patient to have a soft tissue injury.
Ultrasounds can be an alternative to MRI or CT scans. They are less expensive to conduct, and results are usually obtained faster. However, MRI and CT scans are more powerful and better able to differentiate between types of tissue.
If you have an orthopedic condition and need imaging, request an appointment. For your convenience you can have all of your imaging studies done at Summit Medical Group Orthopedics, frequently in the same building as your orthopedist appointment.