From Wikipedia, the free encyclopedia - View original article
|This April 2009 needs additional citations for verification. (May 2009)|
An arthrogram is a series of images, often X-rays, of a joint after injection of a contrast medium. The injection is normally done under a local anesthetic.The radiologist performs the study utilizing fluoroscopy or ultrasound to guide the placement of the needle into the joint and then injects an appropriate quantity of contrast.
The physician or technologist then obtains a series of X-rays, or alternatively computerized tomography (CT) scans or Magnetic resonance imaging (MRI) scans. The joint can be imaged from many angles in fluoroscopy, or on a slice by slice basis in CT and MRI scans.
The physician assesses the images produced.
For pneumoarthrography, a gaseous medium has been used, for opaque arthrography a water-soluble iodinated medium is used, and a combination of both has been used in double-contrast arthrography. Current practice is single contrast arthrography usually coupled with CT or MR imaging.
The exam is usually done under the fluoroscope, or less commonly ultrasound, to guide the needle into the correct place in the joint.
Increasingly utilized in the last ten years, Magnetic Resonance Arthrography and Computed tomography arthrography (CT) combines a standard arthrogram with Magnetic Resonance Imaging or CT scanning. While preparing the iodine contrast for injection into the joint, the physician adds a small quantity (usually less than 1 ml) of gadolinium contrast. Once the joint has been injected, the traditional radiographic images may or may not be obtained, and the patient then undergoes an MR or CT of the joint. The gadolinium in the contrast fluid yields a bright hyperintense signal on T1 weighted images and allows evaluation of quite small defects of the joint capsule, the articular surface of the bones and of the labral cartilage. MR arthrography is most often used in evaluation of the hip and acetabular labrum, of the shoulder rotator cuff and glenoid labrum, and less often in the wrist.
Arthrograms, in practice, can be diagnostic or therapeutic. Therapeutic arthrograms are often joint distention and cortisone injection procedures. A frequent site for such a procedure is the shoulder. Diagnostic arthrograms can be direct, as described above with penetration of the joint, or indirect, by a venous injection of contrast material and later imaging with CT or MRI.
Patients who are allergic to or sensitive to medications, contrast dyes, local anesthesia, iodine, or latex should not have this procedure. Potential risks are infections at the puncture site where the radiopaque substance and/or air are injected. Bleeding is also a small risk.
Reports have arisen of gadolinium contrast agents causing nephrogenic systemic fibrosis (NSF), a debilitating and potentially fatal disease affecting skin, muscle, and internal organs. These cases have only occurred in people with moderate-to-end-stage kidney disease; there have been zero reports of gadolinium leading to health problems in individuals with healthy kidneys. The mechanism linking gadolinium, kidney dysfunction, and NSF is currently unknown. The U.S. Food and Drug Administration (FDA) has recommended that physicians refrain from using gadolinium contrast agents on patients with kidney disease "unless the diagnostic information is essential and can not be obtained with non-contrast-enhanced MRI or other diagnostic procedures." 
Aside from the risk of NSF in people with kidney disease, arthrograms carry the same risks as ordinary X-rays or MRI scans.