Carpal Tunnel Ultrasound and Injection
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An arthrogram is an X-ray image or picture of the inside of a joint (e.g. shoulder, knee, wrist, ankle) after a contrast medium (sometimes referred to as a contrast agent or “dye”) is injected into the joint. An arthrogram provides a clear image of the soft tissue in the joint (e.g. ligaments and cartilage) so that a more accurate diagnosis about an injury or cause of a symptom, such as joint pain or swelling, can be made.
A radiologist (specialist doctor) injects the contrast medium into the joint using fluoroscopy (a special type of X-ray), computed tomography (CT) or ultrasound to help guide the injection needle into the correct position.
Once the injection is finished, images of the joint are taken using magnetic resonance imaging (MRI) or CT. While a plain MRI or CT can provide some information of the soft tissue structures, an arthrogram can sometimes provide much more detailed information about what is wrong within the joint. Improvements in technology and X-ray imaging equipment mean that the use of arthrograms is becoming less common.
Occasionally, an arthrogram is only used to confirm that an injection needle is correctly positioned in the joint. This is usually as part of a treatment of painful joints where medications or anaesthetic need to be injected.
Your doctor will usually send you for an arthrogram as part of an MRI or CT to look at the soft tissue structures inside the joint. If the radiologist carrying out the test feels that using MRI or CT without contrast injection will provide sufficient information, then an arthrogram might not be done.
No specific preparation is usually required.
If you have already had a plain X-ray, ultrasound, CT or MRI of the joint to assess any pain or other symptom you may be experiencing, you will need to bring these scans to your arthrogram appointment.
It may be best to wear comfortable clothing with easy access to the joint being examined.
You will be asked to lie down and the skin over the joint being examined will be cleaned with an antiseptic solution. A local anaesthetic may be injected into the skin to numb the area where the contrast medium will be injected. You may feel a slight stinging sensation.
Using X-ray, ultrasound or CT for guidance, a needle will be placed into the joint, and after ensuring the needle is in the right place, the contrast medium will be injected.
The injection may give you a feeling of fullness in the joint but should not be painful.
The type of contrast medium used depends on the exact nature of the arthrogram and the specialist doctor carrying out the arthrogram. If the arthrogram test uses X-rays (fluoroscopy or CT), this is generally iodinated contrast medium. Occasionally, a CT arthrogram will involve an injection of air either on its own or with a small amount of X-ray contrast medium.
If you are having an MRI arthrogram, the injection will be a very diluted mixture of MRI contrast medium (gadolinium chelates) together with sterile saline (mildly salty water).
After having the injection you will be taken to either an MRI suite (for an MRI arthrogram) or a CT suite (for a CT arthrogram), where detailed imaging of the joint will be carried out.
Many people referred for an arthrogram have symptoms of a sore joint. There can be some mild-to-moderate increase in soreness in the joint for 24–48 hours after the injection. The joint will then return to feeling the way it was before the test.
The injection of contrast medium usually takes about 15 minutes. You may then have to wait a short time before having the additional imaging of your joint. An MRI scan may take 30–45 minutes and a CT scan may take 15 minutes, depending on the joint and the number of scans that have to be done. You should allow approximately 2 hours from arrival at the radiology department.
The procedure to produce an arthrogram is called arthrography. It is a very safe procedure and complications are unusual.
The most serious complication is an infection of the joint. This is usually caused by organisms from the patient’s skin being transferred into the joint during the injection of contrast medium, and for this reason the procedure should not be carried out if there is broken or infected skin over the joint.
The risk of infection is not precisely known, but the best available information suggests that it is in the order of 1 in 40,000 people having the test. If you develop increasing pain in your joint and feel unwell, particularly with a fever, you should see your doctor urgently or contact the radiology facility where you had the procedure done.
Occasionally, people may be allergic to the contrast medium that is injected, and this most commonly results in a rash, but may be more serious. The risk of a minor reaction (e.g. hives) has been reported in 1 in 2000 having the test. More serious reactions appear to be very rare.
Complications of gadolinium contrast medium used in an MRI have not been reported in the very small amounts used in arthrography.
The injection of contrast medium into the joint improves the quality of the MRI or CT to more accurately show damage to the internal structure of the joint.
Some common reasons for an arthrogram are:
There are many other individual situations where your referring doctor may feel that the additional information obtained by an arthrogram could help to determine the best course of treatment.
A radiologist (specialist doctor) will inject the contrast medium into the joint. The radiologist is also responsible for ensuring that the appropriate scans are carried out after the injection, for assessing the images and preparing a formal report of the findings, which is then sent to the doctor who referred you for the test.
Either a nurse or a radiographer (medical imaging technologist) may assist the radiologist in the arthrogram. The radiographer is responsible for taking the images in the arthrogram and the subsequent CT or MRI under the radiologist’s direction.
An arthrogram is carried out in the diagnostic imaging department of most public and private hospitals, and at private radiology facilities.
The time that it takes your doctor to receive a written report on the test will vary, depending on:
The hospital or radiology facility where you are having your test will be able to tell you when your doctor is likely to receive the written report.
It is important that you discuss the results with the doctor who referred you, either in person or on the telephone, so that they can explain what the results mean for you.
Page last modified on 20/10/2017.
RANZCR® is not aware that any person intends to act or rely upon the opinions, advices or information contained in this publication or of the manner in which it might be possible to do so. It issues no invitation to any person to act or rely upon such opinions, advices or information or any of them and it accepts no responsibility for any of them.
RANZCR® intends by this statement to exclude liability for any such opinions, advices or information. The content of this publication is not intended as a substitute for medical advice. It is designed to support, not replace, the relationship that exists between a patient and his/her doctor. Some of the tests and procedures included in this publication may not be available at all radiology providers.
RANZCR® recommends that any specific questions regarding any procedure be discussed with a person's family doctor or medical specialist. Whilst every effort is made to ensure the accuracy of the information contained in this publication, RANZCR®, its Board, officers and employees assume no responsibility for its content, use, or interpretation. Each person should rely on their own inquires before making decisions that touch their own interests.