CONTRAST ARTHROGRAPHY

Overview

The introduction and development of magnetic resonance imaging (MRI) have significantly reduced the number of arthrograms performed in radiology departments. Because MRI is a noninvasive imaging technique, the knee, wrist, hip, shoulder, temporomandibular joint (TMJ), and other joints previously evaluated by contrast arthrography are now studied using MRI (Fig. 12-1). As a result, radiographic contrast arthrography has increasingly specialized functions.

Fig. 12-1 A, Non–contrast-enhanced MRI of shoulder. B, Non–contrast-enhanced MRI of knee, showing torn medial meniscus (arrow).

Arthrography (Greek arthron, meaning “joint”) is radiography of a joint or joints. Pneumoarthrography, opaque arthrography, and double-contrast arthrography are terms used to denote radiologic examinations of the soft tissue structures of joints (menisci, ligaments, articular cartilage, bursae) after the injection of one or two contrast agents into the capsular space.

A gaseous medium is used in pneumoarthrography, a water-soluble iodinated medium is used in opaque arthrography (Fig. 12-2), and a combination of gaseous and water-soluble iodinated media is used in double-contrast arthrography. Although contrast studies may be made on any encapsulated joint, the shoulder is the most frequent site of investigation. Other joints examined by contrast arthrography include the knee, hip, wrist, and TMJs.

Fig. 12-2 Bilateral opaque arthrogram of bilateral congenital hip dislocations.

Arthrogram examinations are usually performed with a local anesthetic. The injection is made under careful aseptic conditions, usually in a combination fluoroscopic-radiographic examining room that has been carefully prepared in advance. The sterile items required, particularly the length and gauge of the needles, vary according to the part being examined. The sterile tray and the nonsterile items should be set up on a conveniently placed instrument cart or a small two-shelf table.

After aspirating any effusion, the radiologist injects the contrast agent or agents and manipulates the joint to ensure proper distribution of the contrast material. The examination is usually performed by fluoroscopy and spot images. Conventional radiographs may be obtained when special images, such as an axial projection of the shoulder or an intercondyloid fossa position of the knee, are desired.

SUMMARY OF PATHOLOGY

Condition	Definition
Dislocation	Displacement of a bone from a joint
Joint capsule tear	Rupture of the joint capsule
Ligament tear	Rupture of the ligament
Meniscus tear	Rupture of the meniscus
Rotator cuff tear	Rupture of any muscle of the rotator cuff

ABBREVIATIONS USED IN CHAPTER 12

MRI	Magnetic resonance imaging
PA	Posteroanterior
TMJ	Temporomandibular joint

See Addendum B for a summary of all abbreviations used in Volume 2.

Contrast Arthrography of the Knee

VERTICAL RAY METHOD

Contrast arthrography of the knee by the vertical ray method requires the use of a stress device. The following steps are taken:

• Place the limb in the frame to widen or “open up” the side of the joint space under investigation. This widening, or spreading, of the intrastructural spaces permits better distribution of the contrast material around the meniscus.

• After the contrast material is injected, place the limb in the stress device (Fig. 12-3). To delineate the medial side of the joint, place the stress device just above the knee and then laterally stress the lower leg.

Fig. 12-3 Patient lying on lead rubber for gonad shielding and positioned in stress device on fluoroscopic table.

• When contrast arthrograms are to be made by conventional radiography, turn the patient to the prone position and fluoroscopically localize the centering point for each side of the joint. The mark ensures accurate centering for closely collimated studies of each side of the joint and permits multiple exposures to be made on one IR. The images obtained of each side of the joint usually consist of an AP projection and a 20-degree right and left AP oblique projection.

• Obtain the oblique position by leg rotation or central ray angulation (Fig. 12-4).

Fig. 12-4 Vertical ray double-contrast knee arthrogram.

• On completion of these studies, remove the frame and perform lateral and intercondyloid fossa projections.

NOTE: Anderson and Maslin ¹ recommended that tomography be used in knee arthrography. In addition, the technique frequently can be used for other contrast-filled joint capsules.

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