N-Trivia

Posted: 03 Sep 2010 03:06 PM PDT

Arthrography allows radiographic examination of a joint after injection of a radioopaque dye, air, or both (double-contrast arthrogram) to outline soft tissue structures and the contour of the joint. The joint is put through its range of motion while a series of radiographs are taken.

Indications for arthography include persistent unexplained joint discomfort or pain. Magnetic resonance imaging of the joint may be used in place of this test.

Arthrography Purpose

To outline joint contour and soft tissue structures
To evaluate persistent unexplained joint discomfort or pain
To identify acute or chronic tears or other abnormalities of the joint capsule or supporting ligaments of the knee, shoulder, ankle, hips, or wrist.
To detect internal joint derangements.
To locate synovial cysts.
To evaluate damage from recurrent dislocations.

Arthrography Patient Preparation

Describe arthrography to the patient and answer any questions he may have. Explain that this test permits examination of a joint.
Inform the patient that he need not restrict food and fluids.
Tell the patient who will perform the procedure and where it will take place.
Explain that the fluoroscope allows the physician to track the contrast medium as it fills the joint space.
Inform the patient that standard X-ray films will also be taken after diffusion of the contrast medium.
Tell the patient that, although the joint area will be anesthetized, he may experience a tingling sensation or pressure in the joint when the contrast medium is injected.
Instruct the patient to remain as still as possible during the procedure, except when following instructions to change position.
Stress to the patient the importance of his cooperation in assuming various positions because films must be taken as quickly as possible to ensure optimum quality.
Check the patient's history to determine if he's hypersensitive to local anesthetics, iodine, seafood, or dyes used for diagnostics tests.

Arthrography Procedure

Knee Arthrography

The knee is cleaned with an antiseptic solution and the area around the puncture site is anesthetized.
A 2" needle is then inserted into the joint space between the patella and femoral condyle and fluid is separated. The aspirated fluid is usually sent to the laboratory for analysis.
While the needle is still in place, the aspirating syringe is removed and replaced with a syringe containing dye.
If fluoroscopic examination demonstrates correct placement of the needle, the dye is injected into the joint space.
After the needle is removed, the site is rubbed with sterile sponge and the wound may be sealed with collodion.
The patient is asked to walk a few steps or to move the knee through a range of motion to distribute the dye in the joint space. A film series is quickly take with the knee held in various positions.
If the films are clean and demonstrate proper dye placement, the knee is bandaged, typically with an elastic bandage.
Tell the patient to keep the bandage in place for several days and teach him how to rewrap it.

Shoulder Arthrography

The skin is prepared and local anesthetics are injected subcutaneously just in front of the acromioclavicular joint.
Additional anesthetic is injected directly onto the head of the humerus.
The short lumbar puncture needle is inserted until the point is embedded into the joint cartilage.
The stylet is removed, a syringe of contrast medium is attached and, using fluoroscopic guidance, about 1 ml of dye is injected into the joint space, as the needle is withdrawn slightly.
If fluoroscopic examination demonstrates correct needle placement, the rest of the dye is injected while the needle is slowly withdrawn and the site is wiped with a sterile sponge.
A film series is taken quickly to achieve maximum contrats.

Nursing Interventions for Arthrography

Tell the patient to rest the joint for 6 to 12 hours.
Wrap the knee in an elastic bandage for several days if a knee arthrography was performed.
Apply ice to the joint for swelling.
Give the patient an analgesic.
Ask the patient to report signs and symptoms of infection.

Arthrography Precautions

Know that arthrography is contraindicated during pregnancy and in the patient with active arthritis, joint infection, or previous sensitivity to radiopaque media.

Arthrography Interpretation

Normal Results

A knee arthrogram shows a characteristic wedge shaped shadow pointed toward the interior of the joint, indicating a normal medial meniscus.
A shoulder arthrogram shows the bicipital tendon sheath, redundant inferior joint capsule, and intact subscapular bursa.

Abnormal Results

Structural abnormalities of the knee commonly suggest tears and lacerations of the meniscus.
Extrameniscal lesion may suggest osteochondral fractures, cartilaginous abnormalities, synovial abnormalities, cruciate ligament tears, and joint capsule and collateral ligament disruptions.
Shoulder abnormalities may suggest adhesive capsulitis, bicipital tenosynovitis or rupture, and rotator cuff tears.

Interfering Factors

Incomplete aspiration of joint effusion dilutes the contrast medium and diminishes film quality.

Arthrography Complications

Hypersensitivity reactions to contrast medium.
Persistent joint swelling, or crepitus.
Infection

Magnetic Resonance Imaging of Bone and Soft Tissue (MRI)

Posted: 03 Sep 2010 02:50 PM PDT

A noninvasive technique, skeletal magnetic resonance imaging (MRI) produces clear and sensitive images of bone and soft tissue. The scan provides superior contrast of body tissues and allows imaging of multiple planes, including direct sagittal and coronal views in regions that can't be easily visualized with X-rays or computed tomography scans. MRI eliminates any risks associated with exposure to X-ray beams and causes no known harm to cells.

There are two types of MRI. Closed MRI uses scanning equipment that resembles a tunnel like chamber. While open MRI uses more sophisticated equipment. During open MRI, the patient can comfortably see the surroundings from all views while the scan is in progress. This is ideal for patients who are claustrophobic or anxious, children, elderly, and the very obese.

Purpose

To evaluate bony and soft-tissue tumors.
To identify changes in bone marrow composition.
To identify spinal disorders.

Patient Preparation

Make sure the scanner can accommodate the patient's weight and abdominal girth.
Explain to the patient that skeletal MRI assesses bone and soft tissue. Tell him who will perform the test and where it will take place.
Explain that the test takes 30 to 90 minutes.
Explain to the patient that although MRI is painless and involves no exposure to radiation from the scanner, a contrast medium may be used, depending on the type of tissue being studied.
If the patient is claustrophobic or if extensive time is required for scanning, explain to him that a mild sedative may be administered to reduce anxiety. Open scanners have been developed for use on the patient with extreme claustrophobia or morbid obesity, but tests using such machine take longer.
An anesthesiologist may need to be present to monitor a heavily sedated patient.
Tell the patient that he must lie flat, and describe the test procedure.
Explain to the patient that he'll hear the scanner clicking, whirring, and thumping as it moves inside its housing.
Reassure the patient that he'll be able to communicate with the technician at all times.
Instruct the patient to remove all metallic objects, including jewelry, hairpins, or watches.
Stop I.V. infusion pumps, feeding tubes with metal tips, pulmonary artery catheters, and similar devices before the test.
Ask whether the patient has any surgically implanted joints, pins, clips, valves, pumps, or pacemakers containing metal that could be attracted to strong MRI magnet. If he does, he won't be able to have the test.
Note and report all allergies.
Make sure that the patient or a responsible family member has signed an informed consent form, if required.

MRI Procedure

At the scanner room door, check the patient one last time for metal objects.
The patient is placed on a narrow, padded, nonmetallic table that moves into the scanner tunnel. Fans continuously circulate air in the tunnel, and a call bell or intercom is used to maintain verbal contact.
Remind the patient to remain still throughout the procedure.
While the patient lies within the strong magnetic field, the area to be studied in stimulated with radio-frequency waves.
If the test is prolonged with the patient lying flat, monitor him for orthostatic hypotension.
Provide comfort measures and pain medication as needed and ordered because of prolonged positioning in the scanner.
After the test, tell the patient that he may resume his usual activity.
Provide emotional support to the patient with claustrophobia or anxiety over his diagnosis.

Nursing Interventions for MRI

Provide patient with comfort measures as needed.
Tell the patient to resume his normal diet and activities unless otherwise indicated.
Monitor vital signs.
Monitor the patient for orthostatic hypotension.

MRI Precautions

Be aware that MRI can't be performed on a patient with a pacemaker, intracranial aneurysm clip, or other ferrous metal implants. Ventilators, I.V. infusion pumps, oxygen tanks, and other metallic or computer based equipment must be kept out of the MRI area.
If the patient is unstable, make sure an I.V. line without metal components is in place and that all equipment is compatible with MRI imaging. If necessary, monitor the patient's oxygen saturation, cardiac, rhythm, and respiratory status during the test. An anesthesiologist may be needed to monitor a heavily sedated patient.
Make sure that the technician maintains verbal contact with the conscious patient.

MRI Interpretation

Normal Results

MRI should reveal no evidence of pathology in bone, muscles, and joints.

Abnormal Findings

MRI is excellent for visualizing disease of the spinal canal and cord and for identifying primary and metastatic bone tumors. It's beneficial in anatomic delineation of muscles, ligaments, and bones. The image show superior contrast of body tissues and sharply defines healthy, benign, and malignant tissues.

Interfering Objects