Sialography

Sialography

CHAPTER OBJECTIVES

After completing this chapter, the reader will be able to perform the following:

Identify the anatomy of the salivary glands

List the indications and contraindications for the procedure

Identify the type of contrast media used for the procedure

Describe the patient preparation for the procedure

List the specialized equipment necessary for the procedure

Describe the patient positioning for the procedure

The radiographic visualization of the salivary glands and ducts is called sialography. The evaluation of the salivary glands is most often accomplished with computed tomography or magnetic resonance imaging; however, sialography becomes the method of choice when a definitive diagnosis is required for pathology such as sialadenitis (inflammation of the salivary glands) and the oral component of ’Sjögren’s syndrome (an autoimmune disease process that causes dry eyes and dry mouth). Sialography involves the introduction of a water-soluble contrast agent into the orifices of the salivary ducts. In most cases, this procedure requires a minimum of specialized equipment and can be performed in a regular radiographic or fluoroscopic room.

ANATOMIC CONSIDERATIONS

The salivary glands secrete saliva into the mouth. Saliva is a liquid that is approximately 99% water. The salivary glands secrete between 1000 and 2000 ml of saliva every day. Found in the saliva are basically two types of materials secreted by the salivary glands—mucus, a combination of mucin and water that is a very viscous substance used to lubricate food particles and maintain oral hygiene, and serous fluid, which contains the enzyme amylase, a substance that begins the digestive process of starches.

There are three pairs of salivary glands—the parotid glands, submandibular glands, and sublingual glands (Fig. 22-1).

FIGURE 22-1 A schematic showing the location of the three pairs of salivary glands and their associated ducts.

Parotid Glands

These are the largest of the salivary glands, with each consisting of a superficial and a deep portion. The parotid glands lie anterior and somewhat inferior to the ear. The deep portion of the parotid gland extends into the neck approximately 0.75 in below and behind the angle of the mandible. The parotid duct, also called Stensen’s duct, is between 5 and 7 cm long. It courses across and to the anterior margin of the masseter muscle, where it turns medially, opening into the mouth opposite the second upper molar tooth. Occasionally, a small accessory lobe may be found, the socia parotidis.

Submandibular Glands

The submandibular glands, also called the submaxillary glands, lie medial to the body of the mandible, with each gland also composed of a superficial and a deep portion. The superficial portion is inferior and anterior to the angle of the mandible, where its posterior portion can be found next to the apex of the parotid gland. It extends anteriorly along the mandibular body. A small, deep portion of the gland curves around the posterior border of the mylohyoid muscle and extends into it. The submandibular duct, also called Wharton’s duct, arises from this deep portion. It averages approximately 5 cm in length, passing anteriorly and medially to the mandible and opening at the sides of the base of the frenulum.

Sublingual Glands

These are the smallest of the three pairs of salivary glands. They are located under the mucosa of the mouth and form a longitudinal ridge at either side of the base of the tongue, the sublingual fold. The sublingual glands, unlike the parotid or submandibular glands, do not have a single duct. There are approximately 12 smaller sublingual ducts, the ducts of Rivinus, coming from the superior border of the gland to open at the sublingual fold. One or two of these ducts, Bartholin’s ducts, may open into the submaxillary duct.

INDICATIONS AND CONTRAINDICATIONS

Sialography is used to demonstrate the relation of the salivary glands to their adjacent structures. It provides both diagnostic and preoperative information in cases of salivary gland pathology. Other indications for sialography are calculi, strictures of the ducts, sialectasia (dilation of a duct), fistulas, and demonstration of pleomorphic salivary gland tumors, commonly called mixed parotid tumors.

Contraindications for this procedure include severe inflammation of the salivary ducts and history of sensitivity to iodinated contrast media.

CONTRAST AGENTS

Two types of contrast media—water-soluble and oily—are used to opacify the salivary glands. The final choice remains with the physician performing the procedure. Certain factors govern the use of a specific type of contrast medium for a particular procedure. Contrast media, such as Ethiodol, have a very slow excretion rate and can cause granulomatous tissue formation, which can be disadvantageous in cases in which complete removal of the contrast medium is impossible. It contains 37% iodine (475mg/ml) combined with ethyl esters of the fatty acids of poppyseed oil. This type of contrast medium provides a greater density in the ducts and parenchyma when tomography is used. For routine sialography, a water-soluble contrast medium is usually used.

PATIENT PREPARATION

Sialography does not require specific preprocedural preparation by the patient. A history should be taken before the study to determine if the patient has allergies or has had prior reactions to iodinated contrast media. It is important to have the patient remove any radiopaque materials such as false teeth or removable bridgework prior to the examination. The patient should be monitored for signs of reaction during the examination. At the conclusion of the study, the patient is usually given a secretory stimulant to clear the contrast medium from the gland and ducts.

PROCEDURE

Scout films of the area of interest may or may not be taken. In cases of suspected sialolithiasis (salivary gland or salivary duct calculi), scout films are mandatory. In cases in which scout films are not taken, stones may be obliterated by the contrast medium, causing an inaccurate diagnosis to be made. The study may be performed with fluoroscopic visualization and spot filming as well as with overhead radiographic projections. Computed tomography, ultrasonography, and magnetic resonance imaging are replacing conventional sialography. Although the primary means of diagnosis has been ultrasonography, conventional sialography still has a place in the realm of interventional radiography for the treatment of pathology of the salivary glands.

After scout films have been taken, the radiologist locates the orifices of the salivary ducts by having the patient express some saliva. The physician can either palpate the salivary gland or have the patient suck on a lemon slice. When the salivary duct is located, it is dilated with standard double-ended blunt dilators or with silver lacrimal probes. After dilation of the orifice, the duct is cannulated. Several types of cannulas are available, but the use of a modified Abbott butterfly set has proved successful in most cases, especially if the patient has to be moved to another location for additional study. The modification is accomplished by filing the beveled tip of the needle flat and smooth with a medium-fine metal file. The wings of the butterfly are then secured with a hemostat. This allows for ease of insertion of the cannula into the duct. The cannula should be prefilled with the contrast medium to avoid injection of air bubbles.

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Tags: Fundamentals of Special Radiographic Procedures

Feb 27, 2016 | Posted by admin in GENERAL RADIOLOGY | Comments Off

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